triangulating point sets in orbit spaces · 2020-05-21 · iii abstract in this work we discuss...

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HAL Id: tel-00552215 https://tel.archives-ouvertes.fr/tel-00552215 Submitted on 5 Jan 2011 HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Triangulating Point Sets in Orbit Spaces Manuel Caroli To cite this version: Manuel Caroli. Triangulating Point Sets in Orbit Spaces. Computer Science [cs]. Université Nice Sophia Antipolis, 2010. English. tel-00552215

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Page 1: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

HAL Id: tel-00552215https://tel.archives-ouvertes.fr/tel-00552215

Submitted on 5 Jan 2011

HAL is a multi-disciplinary open accessarchive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come fromteaching and research institutions in France orabroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire HAL, estdestinée au dépôt et à la diffusion de documentsscientifiques de niveau recherche, publiés ou non,émanant des établissements d’enseignement et derecherche français ou étrangers, des laboratoirespublics ou privés.

Triangulating Point Sets in Orbit SpacesManuel Caroli

To cite this version:Manuel Caroli. Triangulating Point Sets in Orbit Spaces. Computer Science [cs]. Université NiceSophia Antipolis, 2010. English. tel-00552215

Page 2: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

❯❱ P P

♣♦r ♦t♥r ttr

♦tr ♥ ♥s

❯♥rsté ♦♣ ♥t♣♦s

♥t♦♥ ♥♦r♠tq

♣rés♥té t s♦t♥ ♣r

r♥t♥ P♦♥t ts ♥ rt ♣s

ès ré ♣r ♦♥q ❯

s♦t♥

♣♣♦rtrs rt P ür ♥♦r♠t rrü♥♦♥ ❯❱ ❯ r♥

①♠♥trs r ❱ ♦ ♥♦r♠ s♣érr Prs♥♦s ❱ ❯♥rst② ♦ rt♥r ❯♥rsté ♦♦s ♦♥q ❯ ♦♣ ♥t♣♦s étrr♥ért ❱ ❯♥rst② ♦ r♦♥♥♥

♥té ♥rs ♦♠tr②t♦r② r

Page 3: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both
Page 4: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

❯❱❨ P P

P

t♦ ♦t♥ t tt ♦

♦t♦r ♦ ♥s

♦ t ❯♥rst② ♦ ♦♣ ♥t♣♦s

♣t② ♦♠♣tr ♥

♣r♣r ♥ ♥ ②

♥ r♦

r♥t♥ P♦♥t ts ♥ rt ♣s

s♦r ♦♥q

♥ ♦♥

rs rt ♦r♥ P ür ♥♦r♠t rrü♥♦♥ ♥ ❯ r♥

①♠♥t♦rs r ♦♥ ❱rèr ♦ ♥♦r♠ s♣érr Prs♥♦s rs ❯♥rst② ♦ rt♥r ♥r ❯♥rsté ♦♦s ♦♥q ♦♣ ♥t♣♦s étrr♥ért ❱tr ❯♥rst② ♦ r♦♥♥♥

♥t ♥rs r ♦♠tr②t♦r② r

Page 5: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both
Page 6: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

és♠é

♥s tt tès ♥♦s ét♦♥s s tr♥t♦♥s é♥s ♣r ♥ ♥s♠ ♣♦♥ts ♥ss s♣s t♦♣♦♦s ér♥ts ♦s ♣r♦♣♦s♦♥s ♥ é♥t♦♥ é♥ér tr♥t♦♥ ♥② ♣♦r ♣srs sss s♣s ♥s q♥ ♦rt♠ ♦♥strt♦♥ ♦s ♦r♥ss♦♥s ♥ ♠♣♥tt♦♥ ♣♦r s ♣rtr t♦r ♣ttr♠♥s♦♥♥

tr st ♠♦té à ♦r♥ ♣r s♦♥ ♦s ♥t s tr♥t♦♥s ♥② ♣ér♦qs ♥s ♥♦♠r① ♦♠♥s ♦♥t str♦♥♦♠ ♥é♥r s♠tér① ♦♠é ②♥♠q s s t s tr♥t♦♥s ♣ér♦qs ♣♥t êtr s ♦♠♠ s tr♥t♦♥s t♦r ♣t ♦s ♦r♥ss♦♥s ♥é♥t♦♥ t ♥♦s é♦♣♣♦♥s ♥ ♦rt♠ ♥ré♠♥t ♣♦r r tr♥t♦♥ ♥② ♥s t♦r ♣t ♦rt♠ st ♣té ♦rt♠ ♥ré♠♥ts ♥s R

d ♦♥trr s tr① ♥térrs sr s tr♥t♦♥s ♣ér♦qs ♥♦sét♦♥s ♠♥t♥r ♣srs ♦♣s ♣ér♦qs s ♣♦♥ts ♦rsq st ♣♦ss réstt ♦r♥ ♣r ♦rt♠ st t♦♦rs ♥ tr♥t♦♥ t♦r ♣t

♦s ♣rés♥t♦♥s ♥ ♠♣♥tt♦♥ ♥♦tr ♦rt♠ à ♣rés♥t s♣♦♥ ♣q♠♥t ♦♠♠ ♥ ♠♦ ♦tèq ♦rt♠s é♦♠étrqs

♦s é♥érs♦♥s s réstts à ♥ ss ♣s é♥ér s♣s q♦t♥ts ♣ts ♥sqà s s♣s q♦t♥ts ♦rr ♦♥st♥t ♣♦st ♥♥ ♥♦s ♦♥sér♦♥s s t♦r ♦ q st ♥ ①♠♣ ss ♦♣ ♣s r s s♣s q♦t♥ts ♦rr ♥ét ♦♥st♥t

♦tsés tr♥t♦♥ ♥② s♣ q♦t♥t ♦♠♣① s♠♣ tr♥t♦♥ ♣ér♦q t♦r ♣t rêt♠♥t ♦rt♠ ♥ré♠♥t rété ♥♥r♠é

♦r

Page 7: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both
Page 8: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

strt

♥ ts ♦r sss tr♥t♦♥s ♦ r♥t t♦♣♦♦ s♣s ♦r ♥ ♣♦♥t sts❲ ♣r♦♣♦s ♦t ♥t♦♥s ♥ ♦rt♠s ♦r r♥t sss ♦ s♣s ♥ ♣r♦ ♥♠♣♠♥tt♦♥ ♦r t s♣ s ♦ t tr♠♥s♦♥ t t♦rs

♦r s ♦r♥② ♠♦tt ② t ♥ ♦r s♦tr ♦♠♣t♥ tr♠♥s♦♥♣r♦ ♥② tr♥t♦♥s ♥ ♥♠r♦s ♦♠♥s ♥♥ str♦♥♦♠② ♠tr ♥♥r♥ ♦♠ ♦♠♣t♥ ②♥♠s t Pr♦ tr♥t♦♥s ♥ ♥rst♦♦ s tr♥t♦♥s ♦ t t t♦rs ❲ ♣r♦ ♥t♦♥ ♥ ♦♣ ♥ ♥t♥r♠♥t ♦rt♠ t♦ ♦♠♣t ♥② tr♥t♦♥s ♦ t t t♦rs ♦rt♠s ♠♦t♦♥ ♦ t ♥r♠♥t ♦rt♠ ♦r ♦♠♣t♥ ♥② tr♥t♦♥s ♥E

d ❯♥ ♣r♦s ♦r ♦♥ ♣r♦ tr♥t♦♥s ♦ ♠♥t♥♥ sr ♣r♦♦♣s ♦ t ♥♣t ♣♦♥t st ♥r ♣♦ss s♦ t ♦t♣t ♦ ♦r ♦rt♠ s r♥t t♦ ②s tr♥t♦♥ ♦ t t t♦rs ❲ ♣r♦ ♥ ♠♣♠♥tt♦♥ ♦ ♦r♦rt♠ tt s ♥ ♠ t♦ r♦ ♣ s ♣rt ♦ t ♦♠♣tt♦♥♦♠tr② ♦rt♠s rr② ❲ ♥r③ t ♦r ♦♥ t t t♦rs ♦♥t♦ ♠♦r ♥r ss ♦ t ♦rt s♣s s s ♦rt s♣s ♦ ♦♥st♥t ♣♦st rtr ❲ rtr♠♦r ♦♥sr t ♠ rr ss ♦ ♦rt s♣s ♦ ♦♥st♥t ♥trtr

②♦rs ♥② tr♥t♦♥ ♦rt s♣ s♠♣ ♦♠♣① ♣r♦ tr♥t♦♥ t t♦rs ♦r♥ s♣ ♥r♠♥t ♦rt♠ ♦s ♥ ♠♥♦

♦r

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Page 10: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥♦♠♥ts

♦r ♦♠♣s ♥ t ♣rs♥t tss ♦ ♥♦t ♥ ♣♦ss t♦t ts♣♣♦rt ♦ ♠♥② ♣♦♣ tt ♦♠♣♥ ♠ r♥ t st tr ②rs t s ♠♣♦sst♦ ♠♥t♦♥ t♠ t ♥rtss ♦ t♦ s ts ♥s t♦ ♠♥t♦♥ t♦s♦ ♥♥ ♠ ♠♦st

rst ♦ ♦ t♦ t♥ ♠② s♦r ♦♥q ♦r ♥ ♣r♦♣♦s ts♥trst♥ t♦♣ ♥ ♦r ♣t♥ ♠ s st♥t s ②s ♥ ♠ ♦t ♦ s♣♣♦rt t s r ♣sr t♦ t♦ ♦r t r

t s rt ♦♥♦r t♦ ♠ tt rt ♦r♥ ♥ ♦♥ ♥ ♣t t♦ r♠② tss ♠ r② rt t♦ t ①♠♥t♦rs r ♦♥ ❱rér ♥♦s rs ♥r ♥r ♥ rt ❱tr ♦r ♦♠♥ t♦ ♦♣ ♥t♣♦s t♦ tt♥ ♠②♥s rtr t♥ ♥rs r ♦r ♣t♥ t♦ st♥ ①♠♥t♦r

♦ t♦ ♠♥t♦♥ ♦ rt♦ ♦r ♥ strt s♦♠ ♥t rsr s♦r ♣ ♠ s♥♥t② t♦ t strt t t t♦♣ s♦ ♥t t♦ t♥ r♥♥② ♦r rt sss♦♥s ♦♥ ♦r♠③♥ t ♣r♦♠ rt ♦s s ②s ♦r ♠t qst♦♥s ♦r sss♥ ♥trst♥ ♣r♦♠s ♦ ♥② ♥

♥t t♦ t♥ ❱ssr♦♥ s♦♣♦♦s ♥ ♦♥♦ ♦r tr ♦rts t♦ sts ♦♠♣tt② t♥ t Pr♦ tr♥t♦♥s ♥ t r♠sr ♥ t ❱♦♠ ♠sr rs♣t②

r♥ ♠② ♦r t ♦s♦♥ t♦ ♦♦♣rt t rsr t♠s r♦♠ ❯ r③str ♥ r♦♠ t ♥rst② ♦ r♦♥♥♥ tr♥s

♠ rt t♦ t ♣♦♣ r♦♠ r③ s♥ ♦③r ♥ s ♣r♦t t♠ ♣rtr② ❲♦♥ ♥r ♦♠s r♥r ♦r♥rr rt ❱♦t♥r s s r♥③ r♥♠♠r ❲ ♦ts ♦ ♥trst♥ sss♦♥s r♥ ♦r ♠t sts

♥ t s♦♣ ♦ t ss♦t t♠ r sr ♠t sts t ♥ ♥ ❲rt ♥ rt ❱tr r♦♠ r♦♥♥♥ r② ♣♣rt t rt sss♦♥s♦t ♦♥ ♣♣t♦♥s ♦ ♠② ♦ s s ♦♥ ♠② rsr t♦♣ ts

♠ r② t♥ ♦r t s♣♣♦rt ♦t r♦♠ t ♣r♦t r♥ t ♦ ♣r♦ss ♦ ♠♣♠♥tt♦♥ ♥ s♠ss♦♥ ♦ ♠② ♣ ♣♣rt t ♦♣♥ t♠♦s♣r♥ t trst tt s ♣t ♥ ♠ r♦♠ t r② ♥♥♥

r♦ t ♣r♦t r♥s t ♣♦sst② t♦ t ♥ t♦ ♥ ①♥s t r♥ ♦♠♣tr s♥tsts ♥ ♠t♠t♥s ♦♥ ♦♠tr②rt t♦♣s rr♦s ♠t♥s r ②s ♣♦st ①♣r♥ ♥ ♦t♥ ♣r♦ ♠ t ♥ s♦♥ s♣ ♣r♦♠s

Page 11: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥② ♥t t♦ t♥ t rr♥t ♥ ♦r♠r ♠♠rs ♦ t ♣r♦t t♠sé♦♠étr ♥ ♦r tr s♣♣♦rt ♥ t r♥② t♠♦s♣r ♥ t♣sr t♦ ♣ss t tr ②rs ♦ ♠② P sts

♦♥ r② ♣♦st ♥ ♦♣♥ ♥tr♥t♦♥ t♠♦s♣r ♦t t s s♦ts ♦ ♠ t♥ t♦ r②♦② ♠t ♥ ♦ ♥r ♠② st② ♦ ♠♦st♦r ②rs ♥ r♥ ②s ♣ r② ♦♦ ♠♠♦r② ♦ ♠② t♠ ♥ ♦♣♥t♣♦s

ÿ ♠öt ♠ ♠♥r ♠ ♥♥ ♠ stts ♥trstüt③t♥ ♠r r♠öt t ♠♥♥ sr♥ ❲ ③ srt♥

Page 12: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♦♥t♥ts

♥tr♦t♦♥

♦tt♦♥ r♥t♦♥s ♥ E

d ♠♣ ♦♠♣①s ♥② tr♥t♦♥ ♦rt♠s t♦ ♦♠♣t ♥② tr♥t♦♥s ♦ E

d ♥r♠♥t ♦rt♠

rt s♣s Pr♦♠ stt♠♥t tt ♦ t rt ♦♥trt♦♥s

Pr♦ tr♥t♦♥s

t t♦rs ♥② tr♥t♦♥ ♦ T

3c

♥t♦♥ P♦♥t sts tt ♦ ♥♦t ♥ ♥② tr♥t♦♥ ♦ T

3c

♦rt♠ ♦♠♥ ♦♥ ♦♠♥ ❲t ♥② tr♥t♦♥

♥②ss ♦♠♣①t② ♥②ss ♠r ♦ sts

♠♣♠♥tt♦♥

♥tr♦t♦♥ t♦ tr♥t♦♥s

tr♥t♦♥ trts tr♥t♦♥ t strtr

♣r♦ tr♥t♦♥s s♥ sts rts ♦r♥ s♣s P♦♥t ♦t♦♥ P♦♥t ♥srt♦♥

Page 13: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

❱rt① r♠♦ ss ♣t♠③t♦♥s t♦♥ ♥t♦♥t②

♦♠♣①t② t② ♦ ♥ tr♥t s♥ ①♣r♠♥ts

♥♣t ♣♦♥t sts ♦♥strt♦♥ ♦ t ♥② tr♥t♦♥ P♦♥t ♥srt♦♥ ♥ T

3c

tr♥t♦♥ rr② ❱rt① r♠♦ ♣ ♦r♥ ♦♠♥ ♦♠♣rs♦♥ ♦ t rtr ♦ t♦♥

♣♣t♦♥s Pr♦ ♣ s♣s Pr♦ sr ♠sr Pr♦ ♦♠ ♠sr Pr♦ ♦② ♦rt♠

♦♥s♦♥

♥② tr♥t♦♥s ♦ ♦tr s♣s

Pr♠♥rs t s♣s

♦s ♥ ♠♥♦s r♥t♦♥s ♦ ♦s ♥ ♥♦s ♦rt♠ t ♦r♦s

♣r s♣s r♥t♦♥s ♦ t s♣r ♣r ♦rt s♣s r♥t♦♥s ♦ s♣r ♦rt s♣s

②♣r♦ s♣ ②♣r♦ ♣♥ H

2 ♦ t♦rs r♥t♦♥s ♦ t ♦ t♦rs sss♦♥

♦♥s♦♥ ♥ tr ♦r

strt♦♥ t♦ s♠♣ ♦♠♣①s strt♦♥s ♦♥ s♣s ②♣r♦ ♦rt s♣s

Page 14: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣tr

♥tr♦t♦♥

r♥t♦♥s r ♦♥sr t♦ ♦♥ ♦ t ♠♦st ♠♣♦rt♥t strtrs ♥ ♦♠♣tt♦♥♦♠tr② ♥② tr♥t♦♥ s s♣ t②♣ ♦ tr♥t♦♥ tt ①tssr r② ♥trst♥ ♥ s ♣r♦♣rts ♦tr t ts t ❱♦r♦♥♦ r♠t s ♦ rt ♠♣♦rt♥ t♦ ♠♥② ♣♣t♦♥s ♥② tr♥t♦♥ ♥ t ❱♦r♦♥♦r♠ r st ♠♥② ♥t ♦rt♠s r ♥♦♥ ♥ ♠♥② ♠♣♠♥tt♦♥s①st ♦r ♠♦st ♦ ts rsts r rstrt t♦ ♥② tr♥t♦♥s ♥ td♠♥s♦♥ ♥ s♣ E

d♥ ts ♦r ♦♥sr t ♣r♦♠ ♦ ♥♥ ♥ ♦♠♣t♥ ♥② tr♥t♦♥s

♦ s♣s ♦tr t♥ Ed ♥tr♦t♦r② st♦♥ s ♦r♥③ s ♦♦s ❲ rst sss

t ♠♦tt♦♥ ♦r ♦r ♦r ♥ t rqr r♦♥ ♥♦ ♦♥ ♥②tr♥t♦♥s ♥ ♦♥ ♦rt s♣s tr ts ♥tr♦t♦♥s stt t ♣r♦♠ ♦♥sr ♥ ts ♦r ♥② r ♣r♦s ♦r ♦♥ ♥② tr♥t♦♥s ♥❱♦r♦♥♦ r♠s ♦ s♣s ♦tr t♥ E

d ♥ ♣rs♥t ♦r ♦♥trt♦♥s t♦ t t♦♣

♦tt♦♥

s ♦r s ♠♦tt ② ♥s ♦r ♦♠♣t♥ ♣r♦ tr♥t♦♥s ♥ r♥t ♦♠♥s♦ s♥ r r sr rs♦♥s ♦r ♦r♥ ♥ ♣r♦ s♣ rst② t ♥♣t♥ ♣♦♥t st t ♥ ♥r♥t ♣r♦t② ♥♦tr rs♦♥ s tt ♦t♥ t s③ ♦t ♠♦ s t♦♦ t♦ r♥ ♦♠♣tt♦♥s ♦♥ t s♦ t ①♣r♠♥ts r r♥ ♦♥ s♠s♠♣ r♣t ♣r♦② t♦ ♦ ♦♥r② ts ♥ ♥② tr r s♦♠♥trst♥ ♠t♠t qst♦♥s ♦♥ tr♥t♦♥s ♥ ♠ss r t s ♦ ♣r♦tr♥t♦♥s ♥ ♣ t♦ ♥ rtr ♥st ♥ ss t s sr t♦ ♦♠♣t ttr♥t♦♥ ♦ s♠r ♣♦♥t st ♦♥t♥♥ ♦♥② ♦♥ ♣r♦ ♦♣② ♦ ♥♣t ♣♦♥tt♦ ♦ r♥♥② ♥ t ♦♠♣tt♦♥

❲ ♥♦ ♦♥rt ①♠♣s ♦ ♣r♦♠s ♥ r♥t s ♦ s♥ tts ♣r♦ tr♥t♦♥s ♦♠ ♦ t♠ ♥ ♣rs♥t t t Pr♦s♣t ❲♦rs♦♣ ♦♥ ♦♠tr ♦♠♣t♥ ♥ Pr♦ ♣s t ♦♣♥t♣♦sétrr♥é r♥ t♦r ♥ t t ♦rs♦♣ ♥ r♥t♥ s♣s ♦r ♥rst♥♥ t ♦r t t ♦r♥t③ ♥tr ♥ ♥ tr♥s♦♠r

tt♣♦r♥tsPr♦♣s❲♦rs♦♣tt♣♦r♥t③♥tr♥♥♦♣♣s

Page 15: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥tr♦t♦♥

❲ rst ♦♥sr ♥ ①♠♣ ♦ ♥ ♥r♥t② ♣r♦ ♣r♦♠ ♥ ♠tr s♥srsrrs ♦♣ ♥ ♠trs tt s♦ s♦♠ s♣ ♣r♦♣rts ♦r ①♠♣♦s♥ t ❬♦❪ ♦♣ ♦♥ s♦s ♠trs tt ♥ s t♦ r♣r♦♥ ♦♥s ♥ ♦rr t♦ r② t ♠tr ♣r♦♣rts t② s ♥t ♠♥t s♠t♦♥s♦r s♣② t② ♥t t♦ ♦♠♣t ♥②s ♦♠ ♠s ♦ t s♦s s♦s r ♣r♦ ♥ ♦rr t♦ ♠s t ♦ s♦ t ss t♦ ♠s ♦♥② ♦♥♣r♦ ♦♠♥ s tt t ♠s ♥ r♣t ♥ t♦tr s r ❲♥ ♦♠♣t♥ ♥ ♣r♦ stt♥ t♦ ♦♣s ♦ t ♠s t t♦tr ② ♦♥strt♦♥

♥ ♦s♠♦♦② t s ♦ str♦♥♦♠② ♥ t rs strtr ♥ t ♥rs t s♦ ♦s♠♦♦ ♣r♥♣ stts ❱ ♦♥ s♥t② r s t♣r♦♣rts ♦ t ❯♥rs r t s♠ ♦r ♦srrs ❬❪ s ♦r s♠t♦♥s ♦♥t rs strtr ♥ t ♥rs s♥t② r s♠♣ ♦ t strtr ♥ s r♣t ♣r♦② s r ❲ ♥ ♥ ♦♥tt t str♦♥♦♠rs♦ ♦♣ ♥② tsst♦♥ st♠t♦r ❬❲❪ ♥ ♦ r ♥trst♥ s♥ ♣r♦ ♥② tr♥t♦♥s ♥ ❱♦r♦♥♦ r♠s ② r s♦ ♥trst♥ tt ♥♠rs ♦ ♣r♦ ♣ s♣s ❬❲❱P+❪

r♥r ♠trs s♦ ♣rt ♣r♦♣rts t ♠r♦s ♥ ♦♥t♥♠♠♥♣r♦♣rts t ♠r♦s ♦ ♥rst♥ t rt♦♥ t♥ ♦t ♥s ♦ ♣r♦♣rts ♠t♦ s ♦♥ rr② ♦ ♥② tr♥t♦♥s s ♥ ♦♣ ❬rr❪ ♦ ♦ ♦♥r② ts t t♦rs s ♣r♦ stt♥

str♦♣②s s♠t♦♥s ♦t♥ ♦r s♥ ♠t♦ ♣t ♠s r♥♠♥ttt s s ♦♥ rr rs s s t♦ ♣r♦♠s ♥ t s♥ r♥ s♦ tr s♦♠ ♥tr♠t r s③ s s tt s ♥♦t r② ♣t ♦r ①tr♠ss ♦r t r s r♥ r s♠r s♥ s rqr ♠s t ♥♥ ♦t r ♦♥sr② ♠♦r ♦♠♣t ❯s♥ ❱♦r♦♥♦ r♠s ♥st ♦ rr rss♠s ♣t ♦♣t♦♥ ♥ ts s r r ♣♣t♦♥s ♦ ts ♥ ♣r♦ stt♥s ❬❪

♠r ♣♣r♦s r s ♥ ♦♠♣tt♦♥ strtr ♦♦② ❬r❪ ②♥♠s ❬♠ q❪ ♣rt ②♥♠s ❬❪ s♦ ♠♥s ❬❪ ♦♠ ♦♠♣t♥ ❬❲❪ t ts st ♥ r r♦♠ ①st ♦♠ ♦ ts ♣♣t♦♥s s♦ s♦r r♥t t②♣s ♦ ♣r♦ts s s ♣r♦ts ♥ ss t♥ tr rt♦♥s ♥ E

3

♦r ♣♦♥t sts ♥rt ② ♠♦r ♦♠♣t s♦♠trs s s rt♦♥s ♦r r♦tt♦♥sr r s♦ ♠t♠t qst♦♥s r ♣r♦ tr♥t♦♥s ♥ s

♦r ①♠♣ t ♥ Pr♦♠ ❬♦❪ ♦ ♥ s♣ ♣rtt♦♥ ♥t♦ s ♦ q♦♠ t t st r ♦ sr t♥ t♠ r ♦r t tr♥t ♦♥②♦♠ ♣rtt♦♥ t tr♥t ♦tr ♣r♦♣♦s ② ♥ ♠s rs rr♥t② ♣r♦rss ♠ ♦♥ ts t♦♣ s♥ ♣r♦ ❱♦r♦♥♦ r♠s ❬❪ rr ♠♦r t♦♣s ❬♦❪ ♦rs ♦♥ tt ♥♠r s♥trs ♦ ♣♦♥t sts ♥ ♣r♦stt♥

r♥t♦♥s ♥ Ed

♥ ts st♦♥ r♣tt t ♥t♦♥ ♥ t ♣r♦♣rts ♦ t ♥② tr♥t♦♥ ❲ strt t ♥r②♥ ♦♥♣ts s s s♠♣ ♦♠♣①s ♥ tr♥t♦♥s♥ ♥tr♦ ♥② tr♥t♦♥s s♦♠ ♠♣♦rt♥t ♣r♦♣rts ♥ ①♣♥ ♥t t ♥r♠♥t ♦rt♠ tt s s ssq♥t②

Page 16: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

r♥t♦♥s ♥ Ed

r rs strtr ♦ t ♦s♠ ♦rts② ❲rt ♦♥ s♦ ♦rts② ♦s♥ tr♥t ♦♥②♦♠ ♠ ❬♣❪

♠♣ ♦♠♣①s

❲ ♥♦ ♥tr♦ t ♥♦t♦♥s ♦ s♠♣s ♥ s♠♣ ♦♠♣①s ♦r rtr r♥s ❬❩♦♠❪

❲ ♥♦t t d♠♥s♦♥ ♥ s♣ ② Ed st♥ t♥ p ♥ q s

♥♦t ② st(p, q) t ♥t ♦ t t♦r v := q − p r♦♠ p t♦ q s ♥♦t ② ‖v‖ st A ⊆ E

d s s t♦ ♦♥① ♦r ♣♦♥ts p, q ∈ A t ♥ s♠♥t t♥ p♥ q s ♦♥t♥ ♥ A

t p0, p1, . . . pk ♣♦♥ts ♥ Ed k ≤ d ♥r ♦♠♥t♦♥ λ0p0+λ1p1+ . . .+λkpk

t∑k

i=0 λi = 1 λi ∈ R s♣♥s ♥ ♥ rt② ♣♦♥ts r s t♦ ♥②♥♣♥♥t t ♥ rt② s s♣ ♦ ♠♥s♦♥ k

♥t♦♥ ks♠♣① ks♠♣① σ ♥ Ed k ≤ d s t ♦♥① ♦ k + 1

♥② ♥♣♥♥t ♣♦♥ts Pσ = p0, p1, . . . , pk

s♠♣① τ ♥ ② Pτ ⊆ Pσ s ♦ σ ♥ s σ s ♦ s s ♥♦t② σ ≥ τ ♥ τ ≤ σ ♦t tt σ ≥ σ ♥ σ ≤ σ

r ①st sr ♥t♦♥s ♦ s♠♣ ♦♠♣①s ♥ t trtr t♥ t②rstrt t♦ ♥t ♥♠r ♦ s♠♣s ❬❩♦♠ ❱❪ ♥ t sq t ♥♥ts♠♣ ♦♠♣①s s♦ s t ♥t♦♥ ♥ ♥ ❬❪

♥t♦♥ ♠♣ ♦♠♣① s♠♣ ♦♠♣① s st K ♦ s♠♣s stt

σ ∈ K, τ ≤ σ ⇒ τ ∈ K

σ, σ′ ∈ K ⇒ σ ∩ σ′ ≤ σ ♥ σ ∩ σ′ ≤ σ′

r② ♣♦♥t ♥ s♠♣① ♦ K s ♥♦r♦♦ tt ♥trsts t ♠♦st ♥t② ♠♥②s♠♣s ♥ K ♦ ♥t♥ss

♦rs K s ♥t t♥ ♦♥t♦♥ s ②s ❲ s♦♠ ♠♦r ♥t♦♥s t K s♠♣ ♦♠♣① sst ♦ K s

s♠♣ ♦♠♣① s t s♦♠♣① ♦ K str ♦ sst L ⊆ K ♦♥ssts

Page 17: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥tr♦t♦♥

♦ t ♦s ♦ s♠♣s ♥ L

t(L) := σ ∈ K | ∃τ ∈ L, σ ≥ τ.

♦sr L ♦ L s t s♠st s♦♠♣① ♦♥t♥♥ L

L := τ ∈ K | ∃σ ∈ L, τ ≤ σ.

♥ ♦ L s ♥ s ♦♦s

(L) := t(L) − t(L).

r ♦r ♥ strt♦♥ ♦ str ♦sr ♥ ♥ ♥ ssq♥t sss♦♥s

r t t(v) s tr♥s ♥ s s♠♥ts ♥tr t(v) str♥s s s♠♥ts ♥ ♥♥t rts t (v) s ♥s ♥ ♥♥trts

♥trst ♥ t ♥♦♥ ♦ t s♠♣s r♦♠ st L ♥♦t ②⋃L ❲

♥♦t t ♥tr♦r ♦ s♠♣① σ ② σ ♦ s♠♣s σ ♥ τ r s t♦ ♥tr♥②s♦♥t tr ♥tr♦rs r s♦♥t σ ∩ τ = ∅ s r

r σ ♥ τ r ♥tr♥② s♦♥t

♦t tt t ♥t♦♥ ♦ s♠♣ ♦♠♣①s ♥ t ssq♥t ♥t♦♥s r♣r② ♦♠♥t♦r ♥ ♦ ♥♦t ♣♥ ♦♥ t ♠♥ s♣ s ♥ ♦rr t♦ sts ♥t♦♥s ♥ s♣s ♦tr t♥ E

d ♦♥② t ♥ ♦s t s♠♣s rrqr t♦ ♥

❲ ♥ ♥♦ ♦♥sr tr♥t♦♥s r r② s strtrs ♥ ♦♠♣tt♦♥♦♠tr② r♥t♦♥s r ② s ♥ t②♣s ♦ ♣♣t♦♥s s s ♥t ♠♥t♠t♦s ♥ ♠s♥ ❲ rst t ♦r♠ ♥t♦♥

♥t♦♥ r♥t♦♥ t X t♦♣♦♦ s♣ ♥ s♠♣s r♥ tr♥t♦♥ ♦ X s s♠♣ ♦♠♣① K s tt

⋃K s ♦♠♦♠♦r♣ t♦X tr♥t♦♥ ♦ X ♥ ② ♣♦♥t st S s tr♥t♦♥ ♦ X s tt t st♦ rts ♦ t tr♥t♦♥ s ♥t t♦ S

Page 18: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

r♥t♦♥s ♥ Ed

♥ Ed t ♥♦♥ ♦ ♥t ♥♠r ♦ s♠♣s s ♦♠♣t rs E

d ts s ♥♦t ♦♠♣t ♦ ♦r♥ t♦ t ♦ ♥t♦♥ tr s ♥♦ ♥t tr♥t♦♥ ♦ E

d ♦r ♥ ♥ tr♥t♦♥s ♦ t ♦♥♣♦♥t♦♠♣tt♦♥ E

d∪∞ ♦ Ed r ♦♠

♥t♦r s♠♣s ♦r♠ ② ∞ ♥ d ♥t rts r ♦♥sr s ♥♥t ds♠♣sr♦♠ ♥♦ ♦♥ ♥ rr t♦ ♥t tr♥t♦♥ ♦ t ♣♦♥t st S ♥ E

d t②♠♥ tr♥t♦♥ ♦ t ♣♦♥t st S ∪ ∞ ♥ E

d ∪ ∞

♥② tr♥t♦♥

♥② tr♥t♦♥ s ♥♠ tr ♦rs ♥② ♦ s ♦♥ ♦ t rst t♦①♣♦r t r② ♥trst♥ ♥ s ♣r♦♣rts ♦ ts ② ♥♦ st strtr ♥♦♠♣tt♦♥ ♦♠tr② ❬❪

♥ ♦rr t♦ ♥ t ♥② tr♥t♦♥ ♦ Ed ♥ ② ♣♦♥t st rst ♥

s♦♠ ♥♦tt♦♥ t S srt ♣♦♥t st ♥ Ed t σ ds♠♣① t d+1 rts

♦ σ ♦♥ t ♦♥r② ♦ ♥q② ♥ d t r♠sr♥ ♦ σ ♦♥ ♦ t rts ♦ σ s ∞ t♥ t r♠sr♥ ♦ σ s s♣ ♦♥② t ②♣r♣♥ ♥ ② t r♠♥♥ d rts

♥t♦♥ ♥② tr♥t♦♥ ds♠♣① ♥ d♠♥s♦♥ tr♥t♦♥♦s r♠sr♥ ♦s ♥♦t ♦♥t♥ ♥② rt① ♦ t tr♥t♦♥ ♥ ts ♥tr♦r ss t♦ t ♥② ♣r♦♣rt② tr♥t♦♥ ♦ E

d t rt① st S s t♥② tr♥t♦♥ ♦ E

d ♥ ② S ds♠♣① ♥ t tr♥t♦♥ s t♥② ♣r♦♣rt②

❲ rt DT (S) t♦ ♥♦t t ♥② tr♥t♦♥ ♦ Ed ♥ ② S

♦ ①♣♦r ♠♦r ♣r♦♣rts ♦ t ♥② tr♥t♦♥ ♥♦ ♦♥sr ts strtr t ❱♦r♦♥♦ r♠

♥t♦♥ ❱♦r♦♥♦ r♠ ❱♦r♦♥♦ V or(p,S) ♦ ♣♦♥t p ∈ S ♦♥ssts♦ ♣♦♥ts q ♥ E

d s tt st(q, p) < st(q, pi) ♦r pi ∈ S − p ❱♦r♦♥♦ r♠ V D(S) ♦ t ♣♦♥t st S s t ♣rtt♦♥ ♦ E

d ♥t♦ t ❱♦r♦♥♦s ♦ t ♣♦♥ts ♥ S

r ♦r ♥ strt♦♥ ♦ ♥② tr♥t♦♥ ♥ ❱♦r♦♥♦ r♠♥ t ♣♥ ♦r rtr r♥ ♦♥ ♥② tr♥t♦♥s ♥ ❱♦r♦♥♦ r♠ss ❬ ❨ r ❪

r♣ ♦ t ❱♦r♦♥♦ r♠ s t ♦♦♥ ♣r♦♣rts sts ♦rrs♣♦♥ t♦ t rts ♦ t r♣ t ❱♦r♦♥♦ rts ♦rrs♣♦♥ t♦ s ♥ t r♣ t trs ♦ ♥tr♠t ♠♥s♦♥ ♦♦ ♠♣t② ♦ t ❱♦r♦♥♦r♠ ♦ S s t ♥② r♣ ♦ S

❲ s② tt S s ♥ ♥r ♣♦st♦♥ tr s ♥♦ sst ♦ ♠♦r t♥ k +1 ♣♦♥ts tt ♦♥ ♦♥ ks♣r ♦r ♥ ♦♥ k♣♥ ♦r k < d t ♣♦♥ts ♥ S r ♥ ♥r ♣♦st♦♥t♥ t ♥② r♣ s t ♥② tr♥t♦♥

t ♣♦♥ts r ♥♦t ♥ ♥r ♣♦st♦♥ t♥ t ssts ♦ ♦s♣r ♣♦♥ts ♦r♠♦♥① ♣♦②r ♥ t ♥② r♣ ♥ ♦rr t♦ tr♥s♦r♠ t ♥② r♣ t♦ ♥② tr♥t♦♥ ts ♣♦②r ♠st tr♥t s t ♣♦♥ts r ♦s♣r ♥② tr♥t♦♥ ♦ ts ♣♦②r s t ♥② ♣r♦♣rt② ♦r ♣rt ♣r♣♦sst s ♦t♥ s t♦ ②s ♥q② ♥ ♥② tr♥t♦♥ ♦r ♣♦♥t ststt r ♥♦t ♥ ♥r ♣♦st♦♥ ts ♥ s♥ s②♠♦ ♣rtrt♦♥ ❬❪

Page 19: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥tr♦t♦♥

r ♥② tr♥t♦♥ s♦ ♥s ♥ ❱♦r♦♥♦ r♠ s ♥s ♦ ♣♦♥ts ♥ t ♣♥

❱♦r♦♥♦ r♠ ♥ ♥r③ t♦ t ❱♦r♦♥♦ r♠ ♦r ♣♦r r♠ r r t s♦ t s tt t♦ ♣♦♥t ♥ t st S ♥t ♥ st♥ s r♣ ② t ♣♦r st♥ t (p, wp) ♥ (q, wq) ♥♦t♣♦♥ts p ♥ q ♥ E

d t♦tr t tr ts wp ♥ wq rs♣t② ♥ t ♣♦rst♥ s ♥ ②

Π((p, wp), (q, wq)) := st(p, q)2 − wp − wq.

t ♥② tr♥t♦♥ ♦r rr tr♥t♦♥ ♥ ♥ s t ♦ t ♣♦r r♠ ♥ t s♠ ② s t ♥② tr♥t♦♥ s t ♦t ❱♦r♦♥♦ r♠ ❲t ♥② tr♥t♦♥s r ♥r③t♦♥ ♦ ♥② tr♥t♦♥s ♦♠tr② t② ♥ ♥rst♦♦ s ♦♦s t ♣♦♥ts(p, wp) ♥ (q, wq) ♥ ♦♥sr s s♣rs ♦ rs

√wp ♥

√wq ♥tr t p ♥

q rs♣t② ♣♦r ♣r♦t ♦ t♦ t ♣♦♥ts s 0 ♥ ♦♥② t ♦rrs♣♦♥♥ s♣rs ♥trst ♦rt♦♦♥② s t♦ s ♣♦♥ts r s t♦ ♦rt♦♦♥♥♦♦s② t ♣♦r ♣r♦t ♦ t♦ t ♣♦♥ts s strt② ♥t ♦r ♣♦st tt ♣♦♥ts r s t♦ s♣r♦rt♦♦♥ ♦r s♦rt♦♦♥ rs♣t② ♥ ♥♦♥♥rt s d + 1 t ♣♦♥ts ♠t ①t② ♦♥ ♦♠♠♦♥ ♦rt♦♦♥ t♣♦♥t (o, wo) (o, wo) s ♦rt♦♦♥ t♦ ♦ t d + 1 t ♣♦♥ts d + 1t ♣♦♥ts r s t♦ t t ♥② ♣r♦♣rt② ♦r ♥② ♦tr t♣♦♥t ♥ S t ♣♦r ♣r♦t t (o, wo) s ♥♦♥♥t t ♥♣t ♣♦♥t st s ♥♥r ♣♦st♦♥ ♥♦t ♠♦r t♥ d + 1 t ♣♦♥ts t s♠ ♦♠♠♦♥ ♦rt♦♦♥ ♣♦♥t t t ♥② tr♥t♦♥ s t st ♦ ds♠♣s ♦r♠② (d + 1)t♣s ♦ ♣♦♥ts ♥ ts ♣r♦♣rt② ❬❪ ♦r trt♠♥t ♦ ♥rt ss ♦t tt t s♠ ♠♦♥t t♦ t t ♦ ♣♦♥t ♥ S tt ♥② tr♥t♦♥ ♦s ♥♦t ♥ r ♦r t ♥②tr♥t♦♥ ♦r ♠♦r ♦♥ t ♥② tr♥t♦♥s s ❬❪

♦st ♦ t sr ♥ ♣tr ①t♥s t♦ t ♥② tr♥t♦♥s❲r ts s ♥♦t t s trt t ♥② tr♥t♦♥s s♣rt②

Pr♦♣rts ♦ tr♥t♦♥s

s③ ♦ ♥② ♣♥r tr♥t♦♥ s ♥r ♥ t ♥♠r ♦ rts ♥ s♥ s② r♦♠ t rs ♦r♠ t n, e, f ♥♦t t ♥♠r ♦ rts s ♥

Page 20: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

r♥t♦♥s ♥ Ed

r t ♥② tr♥t♦♥ ♦ E2

s ♥ t tr♥t♦♥ rs♣t② ♥ rs ♦r♠ stts tt n − e + f = 2rtr♠♦r s tr s ♥ ♦rrs♣♦♥s t♦ t♦ s ts 2e = 3f P♥ ts ♥t♦ rs ♦r♠ s f = 2n − 4 ∈ Θ(n)

s③ ♦ tr♠♥s♦♥ tr♥t♦♥ ♥ qrt ♥ t ♥♠r ♦ rtst c ♥♦t t ♥♠r ♦ s ♥ e t ♥♠r ♦ s s ♦ rs♦♥ ♦rs ♦r♠ stts n − e + f − c = 0 ♠♣s c ∈ O(e) ♥ s ♥ ② ♣r ♦ rts s♦ t ♥♠r ♦ s s ♥ O(n2) r r ①♠♣s ♦ qrts③ ♥② tr♥t♦♥s s♦ t ♦♥ s tt s r s③ ♦ ♥②

tr♥t♦♥s ♦ Ed s ♦♥ ② O(n⌈ d

2⌉) s tt ♦♥ ❬❪

r qrt s③ ♥② tr♥t♦♥ ♦ E3

♦rt♠s t♦ ♦♠♣t ♥② tr♥t♦♥s ♦ Ed

r r r♦s ♦rt♠s ♥♦♥ ♦r ♦♠♣t♥ t ♥② tr♥t♦♥ ❬♦♦r ❲t❪ rst ♦rt♠s ♥ ♦♣ ♦r ♣♥r ♥② tr♥t♦♥s ② t t② ♦ t ♥② tr♥t♦♥ ♥ t ❱♦r♦♥♦ r♠ ♦rt♠s ♦r ♦♠♣t♥ ❱♦r♦♥♦ r♠s ♦ ♣♦♥t sts ♥ s t♦ ♦♠♣t ♥②tr♥t♦♥s s

♥ E2 t s③ ♦ t ♥② tr♥t♦♥ s ♥ O(n) s s♥ ♦ ♦r ♦♥

♦♥ t ♦♠♣①t② ♦ ♦♠♣t♥ t s ♥ Ω(n log n) s t s♦rt♥ ♣r♦♠ ♥ r t♦ ♥② tr♥t♦♥ ♦♠♣tt♦♥ ♠♥ ♣♦♥ts ♥ ♦♥ ♦♥ ♦t ♥t ♣r♦ ♥♣t ♣♦♥ts r ♣rt ♦ t ♦♥① ♦ t tr♥t♦♥ sr ② ♥ ①trt r♦♠ t tr♥t♦♥ ♥ ♥rs♥ ♦rr ♦ tr x♦♦r♥t ♥ ♥r t♠ s t ♦♥strt♦♥ ♦ t ♥② tr♥t♦♥ ♠st ♥Ω(n log n)

Page 21: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥tr♦t♦♥

r ❯s♥ t ♥② tr♥t♦♥ ♦rt♠ t♦ s♦rt ♣♦♥ts ♦♥ x

❲ r② ♥tr♦ t ♠♦st ♦♠♠♦♥② s ♣♣r♦s t♦ ♦♠♣t ♥② tr♥t♦♥s rst ♦r t ♣♥r s ♥ t♥ ♦r r ♠♥s♦♥s

♥r♠♥t s ♣♣r♦ s ♥t ♥ ♣rt ♥ s② t♦ ♠♣♠♥t t s rst♥ sr ② ❬♦❪ ♥ ❬❲t❪

♥ ♣♦♥t st S t ♦rt♠ strts t tr♥t♦♥ ♦ d + 1 ♣♦♥ts r♦♠ S♥ ♥r ♣♦st♦♥ s ♥ssr② ♥② ♥ ♥srts t r♠♥♥ ♣♦♥ts ♦♥② ♦♥ rst♦r♥ t ♥② ♣r♦♣rt② tr ♣♦♥t ♥srt♦♥ ♣♦♥t ♥srt♦♥♦♥ssts ♦ ♣♦♥t ♦t♦♥ st♣ ♥ ♣♦♥t ♥srt♦♥ st♣

♥ t ♥ ♣♣r♦ t ♣♦♥t ♦t♦♥ st♣ s ♥ O(n⌈ d2⌉) ♥ t ♦rst s

♣♦♥t ♥srt♦♥ st♣ ♥srts t ♣♦♥t ♥t♦ t s♠♣① tt ♦♥t♥s t ♥ rst♦rs t♥② ♣r♦♣rt② ♦rsts ♦♠♣①t② ♦ t ♣♦♥t ♥srt♦♥ st♣ s ts ♦♥② O(n⌈ d

2⌉) r r n ♣♦♥t♦t♦♥ ♥ ♥srt♦♥ st♣s s♦ t ♦r ♦♠♣①t② s

O(n⌈ d2⌉+1)

s rst ♥ ♠♣r♦ ♦♥sr② s♥ r♥♦♠③t♦♥ ♥ ♣♦♥t♦t♦♥t strtr ♥♦♠③t♦♥ ♠♥s r t♦ ♥srt t ♣♦♥ts ♦ S ♥ r♥♦♠ ♦rr ❲♥♦ t rsts ♦ r♥♦♠③ ♦rsts ♥②ss ♦♥sr ♦rsts♣♦♥t st S ♥ r♥♦♠③ ♥srt♦♥ ♦rr

rst rsts ♥ ♦r ♥② tr♥t♦♥s ♦ E2 ♦♥② ❯s♥

♣♦♥t♦t♦♥ tstrtr t ♣♦♥t ♦t♦♥ st♣ ♥ ♠♣r♦ t♦ ♥ ①♣t♦♠♣①t② ♦ O(log n) r s ♣♦♥t♦t♦♥ tstrtrs ♥ ♣r♦♣♦s rqr♥ ①♣t O(n) s♣ ❬❪ rst ♣r♦♣♦s ♥ ♦♥ rs♦♥ t ♣♦♥t st♠st ♥♦♥ ♥ ♥ ❬❪ ♥tr♦ ♥ ♦♥♥ rs♦♥ ♥ ❬ ❪sr ② ②♥♠ ♣♣r♦ ♦♥ ♦r rt① r♠♦ ❲♥ s♥ s ♣♦♥t♦t♦♥ tstrtr ♥ r♥♦♠③ ♥srt♦♥ ♦rr t ①♣t ♦♠♣①t②♦ t ♣♦♥t ♥srt♦♥ st♣ s O(1) s ②s ♥ ♦r ♦♣t♠ r♥♦♠③ ♦rsts♦♠♣①t② ♦ O(n log n)

r♥♦♠③ ♥r♠♥t ♥②ss ♥ s② ①t♥ t♦ E3 rst♥ ♥ ①♣t

t♠ ♥ s♣ ♦♠♣①t② O(n2) s ♦♣t♠ ❬❪ t t② ♥ ①t♥s t♦

d ♠♥s♦♥s ♥ ts s t ①♣t t♠ ♥ s♣ ♦♠♣①t② s O(n⌈ d2⌉) ❬

❪ ❲ sr t ts ♦ t ♥r♠♥t ♦rt♠ ♥ t♦♥ ♦

Page 22: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

r♥t♦♥s ♥ Ed

♦♥qr ♦♥qr ♣♣r♦ t♦ ♦♠♣t ♣♥r ♥② tr♥t♦♥s s ♥ sr ② ❬❪ ♥ ♠♣r♦ ② ❬②❪ t t② ♦♠♣tst ❱♦r♦♥♦ r♠ t ♥② tr♥t♦♥ ♥ t♥ ♦♥strt ♥ ♥r t♠

♣♦♥t st S s ♣rtt♦♥ ♦♥ t x①s ♦r t y①s ♥t♦ t♦ ♦t q②r ssts S1 ♥ S2 ♥ t ❱♦r♦♥♦ r♠s ♦ S1 ♥ S2 r ♦♠♣t rrs②♥② tr s s♥ st♣ tt ♦♠♣ts t ❱♦r♦♥♦ r♠ ♦ S r♦♠ t ❱♦r♦♥♦r♠s ♦ S1 ♥ S2 s ♦rt♠ s t ♦♣t♠ ♦rsts ♦♠♣①t② O(n log n)t ♦s ♥♦t rt② ①t♥ t♦ r ♠♥s♦♥s

♣♥ ♦rt♠ s s ♥ ♥ ♦rt♠ t♦ ♦♠♣t ♣♥r ❱♦r♦♥♦ r♠s❬♦r❪ t ♠♥t♥s ♥ tt s♣s ♦r t ♣♥ ♥ t ❱♦r♦♥♦ r♠ ♦ tr② ♥♦♥tr ♣♦♥ts ♥ t ♥ ts s t ♥ s♣s t ♣♥ t ❱♦r♦♥♦r♠ s ♣t ♦♥ t ② ♥ ♥ ♣♦♥ts ♥♦♥tr ② t s♣♥ r s ♦rt♠ s ♦♣t♠ ♦rsts ♦♠♣①t② O(n log n)

♥r♠♥t ♦rt♠

♠♣♠♥tt♦♥ ♦ ♥② tr♥t♦♥s ♥ t ♦♠♣tt♦♥ ♦♠tr② ♦rt♠s rr② ❬❪ ss ♠♦ rs♦♥ ♦ t ♥r♠♥t ♦rt♠ sr② ♦②r ❬♦❪ ♥ ❲ts♦♥ ❬❲t❪ ❲ ♥♦ ♣rs♥t ♥ ♠♦r t t ♦rt♠s ② t ♠♣♠♥tt♦♥ ❬❨ P❪ ♦♥ ♦r ♦rt♠ t♦ ♦♠♣tt ♥② tr♥t♦♥ ♦ r♥t ♦rt s♣s s s

t rst ①♣♥ t ♠♣♦② ♣♦♥t ♦t♦♥ strt② t♦tr t t♦ ♦♣t♦♥♠♣r♦♠♥ts ♦♥ s♥ ♣♦♥t♦t♦♥ tstrtr ♥ t ♦tr ♦♥ ♣r♦r♠♥s♦♠ ♣r♣r♦ss♥ ♦♥ t ♣♦♥t st ♦r ♦♥strt♥ t tr♥t♦♥ ♥ ♣rs♥tt♦ ♦♠♠♦♥ s♦t♦♥s t♦ rst♦r♥ t ♥② ♣r♦♣rt② ♦ t tr♥t♦♥ tr ♥♥srt ♥ ♣♦♥t ♥ ♥② s♦ ♦ t♦ r♠♦ rt① r♦♠ tr♥t♦♥

P♦♥t ♦t♦♥ ♥ ♦rr t♦ ♥ t tt ♦♥t♥s ♥ ♣♦♥t ♥ ♣♣r♦ r♠♠r♥ st♦st s s ❬P❪ ♣♦♥t ♦t♦♥ ♣r♦r strts t ♥rtrr② c t ♦♦ss t f ♦ t t r♥♦♠ t v ♥♦t t rt① ♦ ctt ♦s ♥♦t ♦♥ t♦ f t qr② ♣♦♥t ♥ v ♦♥ r♥t ss ♦ t ②♣r♣♥♦♥t♥♥ f t ♣♦♥t ♦t♦♥ ♦rt♠ ♣r♦s t♦ t ♥♦r♥ ♦♥ t ♦♣♣♦sts ♦ f ♥ ♦s t s♠ ♥ t r♠♠rs t tt s ♥ st ♦r ♥♦rr t♦ s ♦♥ ♦♠tr tst s t ♦♦ss f t r♥♦♠ ♠♦♥st t s ♦ c trs t ♦♥t♥♥ t ♣♦♥t tr ♥t ♥♠r ♦ st♣s t ♣r♦t②r ♦r ♥ strt♦♥ ♥

s ♥tr♦ ♥ t♦♥ sr ♣♦♥t♦t♦♥ tstrtrs ♥ ♣r♦♣♦s ♥ t ♥② rr② ❬❪ s ♠♣♠♥t ♦rt♠ ♥♠r ♦tr♥t♦♥s ♦ r② s♠r ssts ♦ t ♥♣t ♣♦♥t st r ♠♥t♥ ♦r ♦ ts tr♥t♦♥s tr r ♥s t♥ ♦rrs♣♦♥♥ rts ♥ t ♥①t ♥r ♥t ♥①t ♦rsr tr♥t♦♥ ♥ t rr② ♣♦♥t ♦t♦♥ strts ♥ t ♦rssttr♥t♦♥ t♥ ♦s ♦♥ t♦ t ♥①t ♥r tr♥t♦♥ ♥ strts t r♠♠r♥ st♦st sr ♦ t rt① ♦rrs♣♦♥♥ t♦ t ♦t♣t ♦ t ♣♦♥t♦t♦♥ ♦♥ t ♦rsr tr♥t♦♥

t ♦ ♣♦♥t st s ♥♦♥ t ♥ t ♥ ♦rr ♥ ② tt t♦ sss♣♦♥ts ♥ t ♦rr♥ r s♣t② ♦s ♥ t ♣♦♥t ♦t♦♥ ♥ ♥t③ t

Page 23: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥tr♦t♦♥

r t ❲ ♦♦ ♦♥ ♦ t rr♦s ♦s♥ t r♥♦♠ t♦ t ♦sr t♦ pt ❲t♦t t r♥♦♠ ♦ ♦ t ♥♦r t♦ st t ♦rt♠ ♦ ♥ ♣♥ ♥ ♥♥t ♦♦♣ ♥ ts stt♦♥

t st ♥srt ♣♦♥t ♥ ♣rt ts ♣♣r♦ ②s r② ♦♦ rsts s ♣♣r♦s ♣t s♦rt♥ ❬❪ ♠♣♠♥tt♦♥ ♦r s♦rt♥ ♣♦♥ts s♣t② s ❬❪ t♦rt ♥②ss ♥ ♦♥ ♥ ❬❪

P♦♥t ♥srt♦♥ ♦ ♦ ts st♣ s t♦ rst♦r t ♥② ♣r♦♣rt② ♥ ♥srt♥ t ♥ ♣♦♥t ♥t♦ t tr♥t♦♥ ♥ t t♦♠♥s♦♥ s ♥ ♣♣r♦ s♥s♦ ♣s s ♦t♥ s t t s t t♦ ①t♥ ts ♣♣r♦ t♦ r ♠♥s♦♥s ❬❪ ❲ s ♥ tr♥t ♣♣r♦ ♣r♦♣♦s ♥♣♥♥t② ② ♦②r ❬♦❪♥ ❲ts♦♥ ❬❲t❪ tt ①t♥s s② t♦ d ♠♥s♦♥s ♥ s st ♦r ♠♣♠♥tt♦♥ t♦ ts s♠♣t②

♣♦♥t ♥srt♦♥ s ♦♥ ♥ tr st♣s

♥t② t s tt ♠st ♠♦ t ♦♥t r♦♥

t s r♦♠ t ♦♥t r♦♥

t ♦ rt ♥ st♣ t s s♣♥♥ ② t ♥ ♣♦♥t ♥ t ♦ ts

♦♥t r♦♥ ♦♥ssts ♦ ds♠♣s ♦s r♠sr♥ s ♦♥t♥ t♥ ♣♦♥t s r

♦ ♥ t ♦♥t r♦♥ ♣trst sr ♦rt♠ s s t strts t t ♦♥t♥♥ t ♥ ♣♦♥t ♦r ts ♥♦rs t s tr t② ♦♥ t♦ t♦♥t r♦♥ ♥♦r s ♥ ♦♥t ts ♥♦rs t t r② st ♦♥sr tst rrs② ♥♦r s ♥♦t ♥ ♦♥t t sr s st♦♣♣

♦♥t r♦♥ s strs♣ ♣♦②t♦♣ ♥ t ♥ ♣♦♥t s ♦t ♥ ts r♥ t ♥ ♣♦♥t ♥ s t ♦ ♦♥r② ♦ t ♣♦②t♦♣ rtr♠♦r t ♦♥r②♦ t ♣♦②t♦♣ ♦♥ssts ♦ (d − 1)s♠♣s ② ♦♥strt♦♥ s tr t♥ t ds♠♣s ♥ ♦♥t t s ♣♦ss t♦ ♣ t ♦ ② ♦♥strt♥ ♥ ds♠♣s r♦♠t (d − 1)s♠♣s tt r ts ♦ t ♣♦②t♦♣ ♥ t ♥ ♣♦♥t s s tsr tr♥t♦♥ s r

s ♣♣r♦ rt② ①t♥s t♦ t t ♥② tr♥t♦♥ ♥ ts st ♦♥t r♦♥ ♦♥ssts ♦ ds♠♣s ♦s ♦rt♦♦♥ s♣rs r s♦rt♦♦♥t♦ t s♣r ♥tr t t ♥ ♣♦♥t ♥ ♦s sqr rs s t t ♦ t

Page 24: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

rt s♣s

r t tr♥s ♥ ♦♥t t p t str ♦ p ♥ t ♣t♥② tr♥t♦♥

r ♦♥t r♦♥s ♦r ♥② tr♥t♦♥ t ♥ t ♥②tr♥t♦♥ rt

♥ ♣♦♥t s r s♠ ♣trst sr ♦rt♠ s ♦r t ♥②tr♥t♦♥ ♥ s ♦♥t♦♥ ♦r ts ♦rt♠ t♦ ♦r s tt t ♦♥tr♦♥ ♠st ♦♥trt s tr ♦r t t ♥② tr♥t♦♥

❱rt① r♠♦ ♦r ♥r tr♥t♦♥s rt① r♠♦ s ♥♦t ♣♦ss s r♠♦♥ rt① ♠t ♦ tt ♥♥♦t tr♥t t ö♥rt ♣♦②r♦♥❬❪

♦r t ♥② tr♥t♦♥ ♥ t t ♥② tr♥t♦♥ rt① ♥ r♠♦ ♥ t ♦♦♥ ② rst t rt① ♥ ♥♥t s r r♠♦ r♦♠t tr♥t♦♥ s s ♦ ♦s ♦♥r② s ♣♦②t♦♣ t (d−1)s♠♣s sts ♥ t rts ♦ tt ♣♦②t♦♣ r tr♥t s♥ t ♦rt♠ sr♦ t♦ ♦♠♣t t ♥② tr♥t♦♥ ♦r t t ♥② tr♥t♦♥ ♦ ♣♦♥t st ♦♥r② ♦ t ♦ ♦r♠s s♦♠♣① ♦ ts tr♥t♦♥ ♥ tst ♥tr♦r ♦ ts ♣♦②t♦♣ ♥ s ♥t♦ t ♦

rt s♣s

❲ ♥♦ s♦rt ♥tr♦t♦♥ t♦ ♦rt s♣s ♥ ♦tr ♠t♠t ♦♥♣ts tt s tr♦♦t t tss ❬r♠❪ ♦r rtr r♥

Page 25: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥tr♦t♦♥

t♦♣♦♦ s♣ s st X t♦tr t ♦t♦♥ Ω ♦ ssts ♦ X t t♣r♦♣rts

• ∅ ♥ X r ♥ Ω

• ♥♦♥ ♦ ♥② ♦t♦♥ ♦ sts ♥ Ω s ♥ ♥ Ω

• ♥trst♦♥ ♦ ♥② ♥t ♦t♦♥ ♦ sts ♥ Ω s ♥ ♥ Ω

♦t♦♥ Ω s s♦ t♦♣♦♦② ♦♥ t st X ♥ ♠♥t ω ♦ Ω s ♥♦r♦♦ ♦ ♥ ♠♥t x ∈ X x ∈ ω sst O ♦ X s ♦♣♥ t s ♥♦r♦♦ ♦ ♦ ts ♣♦♥ts sst C ♦ X s ♦s ts ♦♠♣♠♥t s ♦♣♥ t♦♣♦♦s♣ s srt ♠♥ts ♦ X ♣♣r s s♥t♦♥ sts ♥ Ω ♦t tt ♥ srtt♦♣♦♦ s♣ t s♥t♦♥ sts r ♦t ♦♣♥ ♥ ♦s ♥t♦♥ f r♦♠ t♦♣♦♦ s♣ X t♦ t♦♣♦♦ s♣ Y s ♦♥t♥♦s ♦r ♣♦♥t x ♦ X ♥ ♥♦r♦♦ N ♦ f(x) ♥ Y t ♣r♠ f−1(N) s ♥♦r♦♦ ♦ x ♥ X ♦♥t♥♦s ♥t♦♥s r s♦ ♠♣s ♦♠♦♠♦r♣s♠ r♦♠ t♦♣♦♦ s♣ X t♦ t♦♣♦♦ s♣ Y s ♥t♦♥ tt s t ♦♥t♥♦s ♥ s ♦♥t♥♦s ♥rs s ♥t♦♥ ①sts X ♥ Y r ♦♠♦♠♦r♣ ♦r t♦♣♦♦② q♥t

❲ s t ♥♦tt♦♥ G :=< g1, . . . , gk > t♦ ♥♦t t r♦♣ ♥rt ② ♠♥tsg1, . . . , gk t g, h ♠♥ts ♦ G ♦r t♦ r♦♣ ♠♥ts g, h ∈ G t r♦♣ ♦♣rt♦♥tt ♦♠♥s g ♥ h s rtt♥ s gh t♦♣♦♦ r♦♣ s r♦♣ t♦tr t t♦♣♦♦② t t ♣r♦♣rt② tt ♦t t r♦♣ ♦♣rt♦♥ ♥ t ♥t♦♥ ♠♣♣♥ r♦♣ ♠♥t t♦ ts ♥rs r ♦♥t♥♦s r♦♣ s srt t s t♦♣♦♦ r♦♣t t srt t♦♣♦♦② ♥ ts ♦r ♦♥② ♦♥sr srt r♦♣s r♦♣ G ss t♦ t♦rs♦♥r t ♦♥② ♠♥t ♦ ♥t ♦rr s t ♥tt②

t♦♣♦♦ r♦♣ G s s t♦ t s r♦♣ ♦ ♦♠♦♠♦r♣s♠s ♦♥ s♣ X ts ♠♥ts r ♦♠♦♠♦r♣s♠s r♦♠ X t♦ X t r♦♣ ♦♣rt♦♥ s ♦♠♣♦st♦♥ ♦ t♦♦♠♦♠♦r♣s♠s ♥ t ♦♦♥ ♣r♦♣rts r

• (hg)(x) = h(g(x)) ♦r g, h ∈ G ♦r x ∈ X

• e(x) = x ♦r x ∈ X r e s t ♥t ♠♥t ♦ G

• t ♥t♦♥ G × X → X, (g, x) 7→ g(x) s ♦♥t♥♦s

t x ♣♦♥t ♦ X t♦♥ ♦ G s s♦♥t♥♦s t x tr s ♥♦r♦♦U ♦ x s tt g ∈ G | gU ∩ U 6= ∅ s ♥t t♦♥ s s♦♥t♥♦s t s s♦♥t♥♦s t ♥② x ∈ X st ♦ ♠s g(x) ♦r ♠♥ts g ♦ G s t ♦rt ♦ x r♦♠ t t tt G s r♦♣ ♦♦s tt t♦ ♥trst♥ ♦rtsr q ♥ ts ♦rts ♦r♠ ♣rtt♦♥ ♦ X s ♥s t ♦♦♥ q♥rt♦♥ x ∼ y x = g(y) ♦r s♦♠ g ∈ G q♦t♥t s♣ X/G s t st ♦ ♦rts♦ X ♥r t t♦♥ ♦ G r♦♠ ♥♦ ♦♥ s t tr♠ ♦rt s♣ ♦r X/G s ts ♠♦r ♦♠♠♦♥② s ♥ ♦♠tr ♦♥t①ts ♥ ♠♣s③s t t tt ♦♥sr s♣ ♦ ♦rts ❲ X/G t ♦rt s♣ ♦ X ♥r t s♦♥t♥♦s t♦♥ ♦ G ❲s t ♥♦♠♥t♦♥ ② s♥ t ♦♦♥ s♦rt ①♣rss♦♥s t♦ ♥♦t X ♥ G ♥tr r ♥♦ ♠ts X s t ♥r②♥ s♣ ♦ X/G ♥ G s t r♦♣ ♦ t♦♥♥♥ X/G t g ∈ G ♥ p ∈ X ❲ s t s♦rt ♥♦tt♦♥ gp t♦ ♥♦t g(p)

♥♠♥t ♦♠♥ ♦ G s sst ♦ X tt ♦♥t♥s t st ♦♥ ♣♦♥t ♦ ♦rt ♥ ♦t♥ rqrs t ♥♠♥t ♦♠♥ t♦ ♦♥♥t ♥ ♦s ♥ t♦♦♥t♥ ♥♦t ♠♦r t♥ ♦♥ ♣♦♥t ♦ t s♠ ♦rt ♥ ts ♥tr♦r

Page 26: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

Pr♦♠ stt♠♥t

❲ rtr♠♦r ♥ t ♦♥♣t ♦ ♦r♥ s♣s ♥ s ♦♦s

♥t♦♥ ♦r♥ s♣ t X t♦♣♦♦ s♣ ♠♣ ρ : X → X s ♦r♥ ♠♣ ♥ X s s t♦ ♦r♥ s♣ ♦ X t ♦♦♥ ♦♥t♦♥♦s ♦r ♣♦♥t x ∈ X tr s ♥ ♦♣♥ ♥♦r♦♦ V ♥ ♦♠♣♦st♦♥ ♦ρ−1(V ) s ♠② Uα ♦ ♣rs s♦♥t ♦♣♥ ssts ♦ X ♥ s ② tt ρ|Uα

s ♦♠♦♠♦r♣s♠ ♦r α t hx ♥♦t t r♥t② ♦ t ♠② Uα ♦rrs♣♦♥♥t♦ s♦♠ x ∈ X t ♠①♠♠ h := maxx∈X hx s ♥t t♥ X s ♥ hst♦r♥ s♣ ♦ X

♦r♥ s♣ X ♦ X s s t♦ ♥rs ♦r♥ s♣ t s ♦r♥ s♣♦ ♦r♥ s♣s ♦ X ♦r ①♠♣ st ♦r♥ s♣ ♦ r s ♥ r s r r ♥ s ♥rs ♦r♥ s♣ ♦ r

r t r t st ♦r♥ s♣

s♣ s ♠♥♦ ♦ ♠♥s♦♥ d ♦r d♠♥♦ ♦ ts ♣♦♥ts s ♥♦r♦♦ ♦♠♦♠♦r♣ t♦ E

d ♦t tt t♦rs♦♥r r♦♣ ♦s ♥♦t ① ♣♦♥ts gp 6= hp ♦s ♦r p ∈ E

d g, h ∈ G ♥ g 6= h X s ♠♥♦ ♥ G s srt♥ t♦rs♦♥r t♥ X/G s ♠♥♦ ♥ ts s t t♦♥ ♦ G s s♦ ♣r♦♣r②s♦♥t♥♦s G s ♥♦t t♦rs♦♥r t♥ X/G ♥ ♣♦♥ts ♦s ♥♦r♦♦ s♥♦t ♦♠♦♠♦r♣ t♦ E

d s♦ s♥r ♣♦♥ts ♥ ts s X/G s ♥ ♦r♦ s ♥r③t♦♥ ♦ ♠♥♦s ❬ P❪

❲♥ t ♦t rtr ♦ ♠♥♦s ♠♥ ♠♥♥♥ rtr s ♥r③t♦♥ ♦ ss♥ rtr t♦ d♠♥s♦♥ ♠♥♦s ❬❪ ❲ ♦♥sr♦♥② ♦rt s♣s ♦s ♥r②♥ s♣s ♦♥st♥t rtr

Pr♦♠ stt♠♥t

♦ ♦ ts ♦r s t♦ ♥t♦♥ ♦ t ♥② tr♥t♦♥ ♦ r♥t ♦rts♣s ♥ t♦ s ♥t ♦rt♠s t♦ ♦♠♣t t

♥ ♦rt s♣ ♦♥sr s t s♦ t t♦rs t t♦rs ♥ ♥rt② ♥t②♥ ♦♣♣♦st s ♦ sqr s r

r ♥t②♥ ♦♣♣♦st s ♦ sqr ②s t♦rs

Page 27: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥tr♦t♦♥

tr♥t♦♥ ♦ t t t♦rs s ♣r♦ ② ♦♥strt♦♥ t ♥ r♣t ♣r♦② ♥ x ♥ yrt♦♥ ♥ E

2 s r ♥ ♣tr sr ♥ ♠♦r

r ♣r♦ tr♥t♦♥

t ♦ t♦ ♦♥sr t t t♦rs s ♥ ♦rt s♣ t ♥♣t ♣♦♥t st s t♦♦ s♠ ♦r ♥♦t strt t ♦s ♥♦t ♥ tr♥

t♦♥ s ♠♥s tt t ♣rtt♦♥ ♦ t t t♦rs ♥t♦ rts s♠♥ts ♥ tr♥ss ♥♦t s♠♣ ♦♠♣① ♥ ♦♦♥② ♥♦t tr♥t♦♥ s r

r s s ♥♦t s♠♣ ♦♠♣① s t ♥trst♦♥ ♦ σ ♥ τ s p ∪ e s ♥♦t s♠♣①

t s ♥sst r ♦♥ t t tt ♦♠♣t♥ tr♥t♦♥ s♠♣ ♦♠♣①s ♠♣♦rt♥t ♦r sr rs♦♥s rst tr♥t♦♥ s ♥ s s♠♣ ♦♠♣① ♥t trtr ❬r♠ ♥ ♣ ❩♦♠❪ ♦r♦r s♥♥ t strtr t♦ ♥t② st♦r tsst♦♥s tt r ♥♦♥s♠♣ ♦♠♣①s ∆♦♠♣①s ❬t❪ ♦ qt ♥♦ tr♥t♦♥ t strtrtt rs ♥ ♦r ♠♣♠♥tt♦♥ ss♠s t strtr t♦ s♠♣ ♦♠♣①❬P❪ ♥ ♠♦r ♠♣♦rt♥t② ♦rt♠s s♥ tr♥t♦♥ s ♥♣t r② ♦♥ tt tt t tr♥t♦♥ s s♠♣ ♦♠♣① ts s t s ♦r ♥st♥ ♦r ♠s♥♦rt♠s ❬❨ ❨❪ s s ♦rt♠s t♦ ♦♠♣t αs♣s r t②♥ ♥ t ♣r♦ s ② sr ♣♣t♦♥s ♠♥t♦♥ t t ♥♥♥ ♦ ts♥tr♦t♦♥

♥ ♣♣r♦ t♦ rs♦ sss rs♥ ♥ ♦♠♣t♥ t ♥② tr♥t♦♥ ♦

Page 28: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

tt ♦ t rt

♥ ♦rt s♣ s t♦ s sr ①♣t ♦♣s ♦ t ♥♣t ♣♦♥t st r ①♠♣sr ts ♣♣r♦ s s r ♣rs♥t ♥ t♦♥ ❲ ♥t t♦ ♥♠r ♦♦♣s tt s s♥t② r t♦ ♦t♥ s♠♣ ♦♠♣① t s♠ ♥♦ s tt♥ ♠♣♠♥tt♦♥ ♦ ♥ ♦rt♠ s st s ♥ ♣rt ♥♠r ♣♥s ♦♥♦t t ♦rt s♣ ♥ t ♥♣t ♣♦♥t st ❲ s♦ ♠ t ♦r♥ t♦t t♦♥♦♣s ♥r ♣♦ss

tt ♦ t rt

♥ ts st♦♥ sr ①st♥ ♦r ♦♥ tr♥t♦♥s ♥ s♣s ♦tr t♥ Ed s

♣② ♦r ♥ rt♦♥ t♦ ♦rt s♣s t rst ♦♥sr ♦r sss♥ ♥②tr♥t♦♥s ♦ r♥t s♣s ♦ ♦♥st♥t rtr ♥ tr♥ t♦ sss♥ s♦tr ♣s ♥ ♥② ♦♥sr ♣♣rs tt trt t ♣r♦♠ ♦r ♠♦r ♥rs♣s ♥ ♥ ♠♦r ♥r stt♥s

r♠ ♥ árq③ sr ♦ t♦ ♦♠♣t tr♥t♦♥s ♦ ♣♦♥t sts ♦♥ srs ❬❪ ② ①♣t② trt t ss ♦ t ②♥r t s♣r ♥ t t♦rs② ♦ ♥♦t sss t ♥② tr♥t♦♥

♥ st ♦ ♣♦♥ts S ♦♥ sr t② ♥ ♣s♦tr♥t♦♥ s ♠①♠♠st ♦ s♠♥ts r t s♦rtst ♦ss ♦♥♥t♥ t♦ ♣♦♥ts r♦♠ S s tt♥♦ t♦ s♠♥ts ♥trst ② ♦ ♥♦t ♦♥sr ♥rt ss t ♠♣t② ss♠♦ss t♦ ♥q② ♥ s♠♥ts ♦ t ♣s♦tr♥t♦♥ ♣rtt♦♥ tsr ♥t♦ ♣♦②♦♥ r♦♥s t♦rs ♣r♦ t ♦♦♥ rsts s s♦ r

②♥r t ♥♣t ♣♦♥ts r ♥♦t ♦♥t♥ ♥ ♦♥ ②♥r t♥ t ♣s♦tr♥t♦♥ ♣rtt♦♥s t ②♥r ♥t♦ t♦ ♥♦♥ r♦♥s ♥ ♠♥② ♦♥r♦♥s tt r tr♥s

♣r t ♥♣t ♣♦♥ts r ♥♦t ♦♥t♥ ♥ ♦♥ s♣r t♥ t ♣s♦tr♥t♦♥ ♣rtt♦♥s t s♣r ♥t♦ tr♥s ts ♣rtt♦♥ s tr♥t♦♥

♦rs t st ♦♥ qr♥t ♦ t ♥♠♥t sqr ♦ t t t♦rs ♦s ♥♦t ♦♥t♥♥② ♥♣t ♣♦♥t t♥ t ♣s♦tr♥t♦♥ s ♥♦t tr♥t♦♥

② ♦ ♥♦t ♥ ♦rt♠ ♦r ♦♠♣t♥ tr♥t♦♥s ♦ t t♦rs

r t r♥t♦♥ ♦ t ②♥r t Ps♦tr♥t♦♥ ♦ t t♦rs♥♦ ♠♦r s♦rtst ♦ss ♥ t♦t ♥tr♦♥ ♥trst♦♥s ❬❪

Page 29: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥tr♦t♦♥

③ó♥ ♥ ♦ ❬❪ sss t ♦♠♣tt♦♥ ♦ ❱♦r♦♥♦ r♠s ♦♥ ♦r♦s strtr ♦ t ❱♦r♦♥♦ r♠ s t ♥② ♣r♦♣rt② t s ♥♦t ♥ssr② s♠♣ ♦♠♣① ② ♦♥② ♦♥sr qt rstrt ss ♦ ♦r♦s rt s♣s♦ E

2 ♥ S2 ♥r t t♦♥ ♦ srt r♦♣s ♦ s♦♠trs ♥ t ♥ s

ts r t ♣♣r r♦♣s t ♣♦♥t r♦♣s ♥ t r③ r♦♣s ♥ t s♣rs t ♣♦♥t r♦♣s ♦♥② ❬❪ t G ♦♥ s r♦♣ ♥ S t ♥♣t ♣♦♥tst G s ♥♥t t♥ GS t st ♦ ♣♦♥ts ♥ t ♦rts ♦ t ♣♦♥ts ♦ S s♥♥t t V D(S) ♥♦t t ❱♦r♦♥♦ r♠ ♦ S ♥ E

2 ♦r S2 t♦rs s♦ tt

♦r ♥② G tr s ♥t ♣♦♥t st S∗ ⊂ GS ♥ ♥♠♥t ♦♠♥ F s ttV D(S∗) ∩ F = V D(GS) ∩ F s ♠♥s tt V D(S∗) ∩ F ♥r t t♦♥ ♦ G s t♥♥t ❱♦r♦♥♦ r♠ ♦ GS s r ♦ r s t♦ ♦♠♣t s s

r t ❱♦r♦♥♦ r♠ ♦ tr ♣♦♥ts ♦♥ ②♥r t ♥ s ♥♦ ♦r ❬❪

♥ ♦ t♦rs ♣r♦ tt ♥ t ♦rst s ♦r t ♦rst r♦♣s S∗

♦♥ssts ♦ ♣ t♦ ♦♣s ♦ t ♣♦♥t st S♥ ts ♣♣r♦ t ♦♠♣tt♦♥ ♦ t ❱♦r♦♥♦ r♠ s ♦♥ ♥ E

2 ♦r S2 rs♣

t② s ♥② ♦ t ♥♦♥ ♦rt♠s ♦ ♦♠♣①t② O(n log n) ♥ s st ♥♠r ♦ ♣♦♥ts ♥ S∗ s t ♠♦st t♠s t ♥♠r ♦ ♣♦♥ts ♥ S ts ♦s ♥♦t♥ t s②♠♣t♦t ♦r ♦ t ♦rt♠ t t ♦s ♥♦t ♣♣r r② ♣rttr ♥ tt t ♦rt♠ s s♦ ♦♥ ② t♦r ♦ t st 37 ♥ t ♦rst s

♥♥② ♥ ❬❪ ①♠♥ tr♥t♦♥s ♦ t ♣r♦t ♣♥ s♥ ♦rt s♣ ♦ S

2 ♥r t t♦♥ ♦ t r♦♣ ♥t②♥ t♦ ♥t♣♦ ♣♦♥ts ②s ♥ ♥r♠♥t ♦rt♠ ♥ strt t ♥ ♥t tr♥t♦♥ ♦ s① ♦ t ♥♣t♣♦♥ts ② r♣rs♥t t tr♥t♦♥ ♥ ♣r♦r♠ t ♦♠♣tt♦♥s ♥ t ♣r♦t♣♥ ts ② s♦ t ♣r♦♠s rs♥ t♦ t t tt t ♣r♦t ♣♥ s♥♦t ♦r♥t tr♥t♦♥s t② ♦♠♣t ♦ ♥♦t t ♥② ♣r♦♣rt②

♦♥ ♥ s♦♥ ❬❪ s♦ tt ♥ t s ♦ t tr♠♥s♦♥ t t♦rs ♣r♦ ♥② tr♥t♦♥ ♥ ①trt r♦♠ ♥② tr♥t♦♥ ♦ ♦♣s ♦ t ♣♦♥t st ♥ t♦♥ ♣rs♥t ♣rt ♦ tr ♣r♦♦ ♥ ♠♦r t② ♦ ♥♦t sss tr t ♥♠r ♦ rqr ♦♣s ♥ r ♣♥♥♦♥ t ♥♣t ♣♦♥t st ② ♦ ♥♦t ♦r ♥ t t t♦rs t ♦♥sr ♥♠♥t♦♠♥ ♥ ② t ❱♦r♦♥♦ ♦ s♥ ♣♦♥t ♥ t t♦rs ♥ t② ♦♠♣t t♥② tr♥t♦♥ ♦ t ♦♥① ♦ t ♥♣t ♣♦♥t st ♥s t ♥♠♥t

Page 30: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

tt ♦ t rt

♦♠♥ t♦tr t ts ♦♣s ♥ t ♥t ♥♠♥t ♦♠♥s ♥ E3 r

♦rt♠ ♦rs ♥ tr st♣s

t S t ♥♣t st ♦ ♣♦♥ts ♥ t ♥♠♥t ♦♠♣t t st S∗ ♦ ♦♣s ♦ ♣♦♥t ♥ S

♦♠♣t t ♥② tr♥t♦♥ ♦ S∗ ♥ E3

①trt t s♠♣s r♦♠ t ♥② tr♥t♦♥ ♦ S∗ tt r ♣rt ♦ t♥♥t ♣r♦ ♥② tr♥t♦♥

♦t♣t ♦ ts ♦rt♠ s st ♦ ttrr ♦s ♥♦♥ s ♥♠♥t ♦♠♥♦ t tr♠♥s♦♥ t t♦rs

♥ s ts ♣♣r♦ t② ♦♠♣ts ♥② tr♥t♦♥ ♥ E3 t ♥ s

♥② ♦ t ♥♦♥ ♦rt♠s ♦r t ♥♠r ♦ ♥♣t ♣♦♥ts t♦ t ♦rt♠ s t♠s rr t♥ t ♥♠r ♦ ♣♦♥ts ♥ S s ♦s ♥♦t ♥ t t♦rt♦♠♣①t② ♦ t ♦rt♠ t ♦r ♣rt s t ♦ ♥ t♦ r t ♥♠r♦ rqr ♦♣s ♦ t ♥♣t ♣♦♥ts

♦tr

♥ t ♥♥r♥ ♦♠♠♥t② ♦♠♣s♦♥ ♣r♦♣♦s ♥ ♦rt♠ ♦r ♦♠♣t♥ ♥②tr♥t♦♥s ♦ t tr♠♥s♦♥ t t♦rs ♦♥ ♣t♦♥s ♦ ♣♦♥ts ❬♦❪♦r t ♦rt♠ ② rs ♦♥ t ss♠♣t♦♥ tt t ♥♣t ♣♦♥t st s s♥t② r ♥ strt t strts t ♥ ♥t tr♥t♦♥ ♦ t rts♦s t♦ t ♦r♥rs ♦ t ♥♠♥t s ♥t strtr s ♥♦t s♠♣♦♠♣① ♥ t s ♥♦t rqr t♦ t ♥② ♣r♦♣rt② P♦♥ts r trt② s♥ sr t♥qs ♥ ♦rr t♦ ♥ ♥♦♥sst♥s t♦ ♦t♥♣♦♥t rr♦rs♥ ♦r r♦♥ t♠ ❬❪ ♠ s tt t ♥♣t ♣♦♥t st s s♥t②r ♥ strt t♥ t ♥ ♦t♣t ♥② tr♥t♦♥ ♦ ttr♠♥s♦♥ t t♦rs ♠ s s♣♣♦rt ② ①♣r♠♥ts ♦♥ strtt ♦ ♣r♦♦s r ♣r♦ ①♣r♠♥ts ①t r♥♥♥ t♠ ♦ ♦t O(n1.11)❯♥♦rt♥t② t ♦ s ♥♦t s♦ ♦ ♥♦t ♦♠♣r t t♦ ♦r ♠♣♠♥tt♦♥

♦♥ ♥ r♦t t s♦tr ♣ s ♦r ♦♠♣t♥ ♦t ♣r♦ ♥♥♦♥♣r♦ ❱♦r♦♥♦ r♠s ❬❪ ♦r t ts t♦ ♥ s ♥♦t ♠♥t♥② t t♦r ♥②♠♦r ♥ s ♦ ♣r♦ ❱♦r♦♥♦ r♠s t ♦rs t ♦♣s ♦ ♥♣t ♣♦♥t

rtr♠♦r tr r ♦tr ♠♣♠♥tt♦♥s r♦♠ rsrrs ♣t t♦ tr s♣ s ♦r ♥st♥ ❱♦r ♣r♥ ♠♣♠♥t ♣r③ rs♦♥ ♦ t♦♠♥s♦♥ ♣r♦ ♠s ♥rt♦r t♦ r♥ ①♣r♠♥ts ♦♥ ②♥♠s ❬♣r ♣r❪t s ② ♣t t♦ t s rr ♥ t s ♥♦t ♥t♥ t♦ ♦r ♣s

♦r ♥r s♣s

♦♠ ♦r ♦♥ tr♥t♦♥s ♥ ♠♦r ♥r s♣s ♥ ♣ssr♥♥r ♥ sss tr♥t♦♥s ♥ ♥r t♦♣♦♦ s♣s ❬❪

♦r t② ss♠ t s♣ t♦ ♠ ♥ Ed ♥ t② s♣♣♦s tt t② r

♥ s♥t② s♠♣ ♣♦♥t st ♥ t② ♦♠♣t t ♥② tr♥t♦♥

Page 31: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥tr♦t♦♥

♦ t ♣♦♥t st ♥ Ed ♥ ♥ t tr♥t♦♥ ♦ t ♥ t♦♣♦♦ s♣ t♦

rstrt♦♥ ♦ t tr♥t♦♥ ♥ Ed ♥ s ② t rstrt ♥② tr♥t♦♥

s s♦♠♣① ② ♦♥strt♦♥ ♥ ts tr♥t♦♥ t sss♦♥ ♠st tr♠♥♥ tr t rstrt tr♥t♦♥ s ♦♠♦t♦♣② q♥t t♦ t ♥t♦♣♦♦ s♣ s t♦♣ s ♥ st t♦ ①t♥s rsr s ♦r ♥st♥ ❬ ♣ ❪

♦ rrs ♥ s♦♥ sss ♦r♦ tr♥t♦♥s ♥ r②st♦r♣ r♦♣s❬❪ r ♣r♦♠ s ♥ s♦♠ s♥s ♥rs t♦ t ♣r♦♠ ♥t t♦ sss ♥ tr♥t♦♥ ♦ s♣ ♥ t ♦rrs♣♦♥♥ s♣ r♦♣ t r♦♣ G s ttt ♥ tr♥t♦♥ s tr♥t♦♥ ♦ t ♦rt s♣ E

3/G

♦♥trt♦♥s

❲ ♠t♠t② s♦♥ ♥t♦♥ ♦ t ♥② tr♥t♦♥ ♦ t tr♠♥s♦♥ t t♦rs ♥ ② st ♦ ♣♦♥ts ❲ ♣r♦♣♦s ♦♥sst♥t ♣♣r♦ ♦trt♥ ♣♦♥t sts tt ♦ ♥♦t ♥ ♣r♦ ♥② tr♥t♦♥ s♥ ♦r♥s♣s ❲ ♣r♦ ♦♥t♦♥s t♦ tr ♣r♦ ♥② tr♥t♦♥ ♦ ♦r♥ s♣ ♦ t t t♦rs ♥ ♦♥rt t♦ ♥② tr♥t♦♥ ♦ t tt♦rs ts ♥ s♠♣ ♦♠tr rtr t♦ r② ts ♦♥t♦♥s

❲ ♣rs♥t ♥ ♣tt♦♥ ♦ t ♥♦♥ ♥r♠♥t ♦rt♠ ♥ E3 ❬♦

❲t❪ tt ♦s t♦ ♦♠♣t ♥② tr♥t♦♥s ♦ t tr♠♥s♦♥ t t♦rs❲ ♦s ♦♥ t ♥r♠♥t ♦rt♠ ♦r sr rs♦♥s ts ♣rt ♥② s ♥♣r♦ ♥ ♣rtr ② t ② ②♥♠ ♠♣♠♥tt♦♥ ♥ ❬P❪ ♠♦r♦r ②♥♠ ♦rt♠ ♦♥ t♦ r② ♥srt ♥ r♠♦ ♣♦♥ts s ♥ssr② ♥r♥t ♦r ♠s♥ ♦rt♠s ♥ s♦tr s ♦♥ ♥② r♥♠♥t ♠t♦s s♦r ♥st♥ ❬ ❨ ❪ ❲ ①t♥ t ♦ ♦r t♦ r♥t sss ♦tr♥t♦♥s s s t ♥② tr♥t♦♥s

❲ s♦ ♣r♦ ♥ ♠♣♠♥tt♦♥ ♦ t ♦rt♠ s♦tr s ♥ r♥ ♣t ② t t♦r ♦r ♦r ♥s♦♥ ♥ rs♦♥ ♦ t rr②❬❪ s s♦tr s ♠♦♥strt ② ♦ ❬❪ ❲ r ♥ ♦♥tt t srs ♦♦r ♠♣♠♥tt♦♥ ♥ tr s t st ♦♥ ♣t♦♥ rrr♥ t ❬♦❪

❲ sss ①t♥s♦♥s tt ♦ ♦r s♥ ♦r ♦ ♥ ♦♠♥t♦♥ t ♦tr ♦♠♣♦♥♥ts s s t ♣ s♣ ♣ ❬❨❪ ♦r t sr ♠s ♥ ♦♠ ♠s♥rt♦rs ❬❨ ❨❪

❲ ①t♥ ♣rts ♦ ♦r ♦r ♦♥ ♥② tr♥t♦♥s ♦ t t t♦rs t♦ r♥tsss ♦ s♣s s s ♦rt s♣s ♦ t d♠♥s♦♥ ♥ s♣ E

d ♥ td♠♥s♦♥ s♣r S

d ❲ ♣rs♥t s♦♠ ♣r♠♥r② s ♦♥ ♦ t♦ ①t♥ t s♦ t♦♦rt s♣s ♦ t ②♣r♦ s♣ H

d

tss s ♦r♥③ s ♦♦s ♥ ♣tr sss ♣r♦ tr♥t♦♥s ♥t ❲ ♣rs ♥t♦♥ s s ♥ ♦rt♠ ♥ ♣r♦ sr ♠♣♦rt♥t♣r♦♣rts ♥ ♣tr sr t ♠♣♠♥tt♦♥ ♥ s♦ s♦♠ ①♣r♠♥ts ♥ ♣♣t♦♥s ♣tr s t ①t♥♥ t t♦r② ♦♣ ♥ ♣tr ♦♥t♦ rtr t ♦rt s♣s s s s♣r ♥ ②♣r♦ ♦rt s♣s

Page 32: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣tr

Pr♦ tr♥t♦♥s

♥ ts ♣tr rst s♦ ♦ t♦ ♥ t t t♦rs s ♥ ♦rt s♣ ♥ t ♠♥♣rt ♦ t ♣tr s♦ ♦ t♦ ①t♥ t ♥t♦♥ ♦ ♥② tr♥t♦♥ t♦t tr♠♥s♦♥ t t♦rs ♥ ♣rs♥t ♥ ♦rt♠ ❲ ①t♥ t ♦rt♠ t♦t ♥② tr♥t♦♥s ❲ ♥② ♣r♦ t ♦rrt♥ss ♦ t ♦rt♠ ♥s♦ tt t s r♥♦♠③ ♦rsts ♦♣t♠ ♦♠♣①t② ♦ O(n2)

t t♦rs

t rst ♣rs ♥t♦♥ ♦ t t t♦rs tt ♦♥sr tr♦♦tt rst ♦ t ♣tr ♥ r s♦♠ ♦ ts ♥♦♥ ♣r♦♣rts ♥ sts♥♦tt♦♥ ♥② ♥t♦♥ ♦ s♠♣s ♥ t t t♦rs

t tx ty ♥ tz ♥♦t t ♥t tr♥st♦♥s ♦♥ t x y ♥ z①s ♥ E3

rs♣t②

♥t♦♥ T3c t c := (cx, cy, cz) ∈ (R\0)3 ♥ G t r♦♣ < cxtx, cyty, cztz >

♦rt s♣ E3/G s t t♦rs ♥ ♥♦t t ② T

3c ❲ rtr♠♦r ♥♦t t

♣r♦t♦♥ ♠♣ ② π : E3 → T

3c

♥♦tr ♦♠♠♦♥② s ♥♦♠♥t♦♥ s ♥ t♦rs ❬❪ r t ♦r ♥ ♠♥s tt t s♣ s ♦♥st♥t ♠♥♥♥ rtr ③r♦ t s t♦rss t s ♦♠♦♠♦r♣ t♦ t tr♠♥s♦♥ t♦rs ♠ ♥ E

4 t t♦rs T

3c tt ♦♥sr r s d♦ s ♥♠♥t ♦♠♥ ♦r

♥r t t♦r t ♥♠♥t ♦♠♥ s ♥♦t rstrt t♦ ♦s t ♥ d♠♥s♦♥ ♣r♣♣ ♥r s s trt ♥ t♦♥

♦t tt t ♦rts ♦ G r s♦♠♦r♣ t♦ Z3 ♥ T

3 × Z3 s s♦♠♦r♣ t♦ E

3 T3 s

♠tr s♣ t stT(π(p), π(q)) := min st(p′, q′) ♦r p′ ∼ p, q′ ∼ q ♦t tt π s♦♥t♥♦s

♦♥sr t ♦s ♦ [u, u + c0]× [v, v + c1]× [w,w + c2] s ♥♠♥t

♦♠♥ ♦r G ♦♣♥ ♦ Dc = [0, cx) × [0, cy) × [0, cz) ♦♥t♥s ①t② ♦♥

r♣rs♥tt ♦ ♠♥t ♦ T3c ❲ t ♦r♥ ♦♠♥ ❲ ♥♦t ♦♦r♥t

s t♦r ♠t♣t♦♥ ② ∗ (ax, ay, az) ∗ (bx, by, bz) := (axbx, ayby, azbz) ♦t ttts ♥ s♦ ♥rst♦♦ s ♠tr① ♠t♣t♦♥ r t a ♥ b r t ♥trs

Page 33: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

Pr♦ tr♥t♦♥s

♦♥ t ♦♥s ♠♣

ϕc : Dc × Z3 → E

3

(p, ζ) 7→ p + c ∗ ζ

s t ♦♥st ♦♥ ♦ Dc s ♥t ‖c‖ ❲ s② tt t♦ ♣♦♥ts p1, p2 ∈ E3

r ♣r♦ ♦♣s ♦ ♦tr t② ♦t ♥ t s♠ ♦rt ♦r q♥t② trs ♣♦♥t p ∈ Dc s tt p1, p2 ∈ ϕc(p × Z

3)♦ tr♥ t♦rs t ♥t♦♥ ♦ s♠♣s ♥ T

3c r s ♥♦ ♠♥♥ ♥t♦♥

♦ ♦♥① ♥ T3c ♥ ttrr♦♥ s ♥♦t ♥q② ♥ ② ♦r ♣♦♥ts ❲ tt

t rt① ♥ ♥tr t♦r ♥♠ ♦st tt s♣s ♦♥ r♣rs♥tt ♦t ♦♥ ♦rt s r ♥tt② t ♦sts tr♠♥ ② s♠♣① r♣sr♦♥ t t♦rs ♥ t ♦ ♥t♦♥ ♦ ϕc t ♦sts r t ♥♠rs ζ ∈ Z

3

r strt♦♥ tr ♣♦♥ts p1, p2, ♥ p3 ♦ ♥♦t ♥q② ♥ tr♥ r♥ tr♥ s t tr♥ (p1,

(00

)) (p2,

(10

)) (p3,

(11

))

s s♥ ♥ t♦♥ t s♠♣ ♦♠♣① ♥t♦♥ s ♣r② ♦♠♥t♦r ♥♦s ♥♦t ♣♥ ♦♥ t s♣ ♥② t s♠♣① ♥t♦♥ ♠st ♣t t♦ T

3c s

♥ ♦♥ ♥ s♠r ② s ♥ ❬❲❪

♥t♦♥ ks♠♣① ♥ T3c t P st ♦ k+1 k ≤ 3 ♣♦♥t♦st ♣rs (pi, ζi)

♥ Dc×Z3 0 ≤ i ≤ k t (P) ♥♦t t ♦♥① ♦ ϕc(P) = pi+c∗ζi | 0 ≤ i ≤ k

♥ E3 t rstrt♦♥ π|(P) ♦ π t♦ t ♦♥① ♦ P s ♥t t ♠ ♦ (P)

② π s ks♠♣① ♥ T3c

♥ ♦tr ♦rs t ♠ ♥r π ♦ s♠♣① ♥ E3 s s♠♣① ♥ T

3c ♦♥② t

♦s ♥♦t s♥trst ♦r t♦ r s♦s t ♦♥① s A B ♥ C ♦ tr♣♦♥t♦st ♣rs ♥ [0, 1)2 ×Z

2 rs♣t②(p1,

(02

))s ♣♦♥t ♥ t ♦rt ♦ rt① ♦

A tt s ♥s A tr rts ♦ B r ♥ t s♠ ♦rtr r ♥♥t② ♠♥② sts ♦ ♣♦♥t♦st ♣rs s♣②♥ t s♠ s♠♣①

♥t♦♥ ♦ ♥ ♦ s ♣t ♦r♥② t σ ks♠♣① ♥ ② stPσ ⊆ Dc × Z

3 s♠♣① τ ♥ ② st Pτ ⊆ Dc × Z3 s ♦ σ ♥ s σ s

♦ ♥ ♦♥② tr s s♦♠ ζ ∈ Z3 s tt (pi, ζi + ζ) | (pi, ζi) ∈ Pτ ⊆ Pσ

♥② tr♥t♦♥ ♦ T3c

s st♦♥ s ♦r♥③ s ♦♦s t rst ♥t♦♥ ♦ t ♥② tr♥t♦♥ ♦ T

3c ❲ ♦sr tt tr r ♣♦♥t sts ♥ T

3c tt ♦ ♥♦t ♥ ♥②

Page 34: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥② tr♥t♦♥ ♦ T3c

A

C

(p0,

(2

2

))(p1,

(2

2

))

(p2,

(2

2

))

(p0,

(2

1

))(p1,

(2

1

))

(p2,

(2

1

))

(p0,

(0

0

))

(p1,

(0

0

))(p2,

(0

0

))

(p0,

(1

1

))(p1,

(1

1

))

(p2,

(1

1

))

(p0,

(2

0

))(p1,

(2

0

))

(p2,

(2

0

))

(p0,

(1

2

))(p1,

(1

2

))

(p2,

(1

2

))

(p0,

(0

2

))

(p1,

(0

2

))(p2,

(0

2

))

(p0,

(0

1

))(p1,

(0

1

))

(p2,

(0

1

))

(p0,

(1

0

))(p1,

(1

0

))

(p2,

(1

0

))

B

r strt♦♥ π(A) ♥ π(B) r ♥♦t s♠♣s ♦r π(C) s s♠♣①

tr♥t♦♥ ♦ T3c ♥ ♥ssr② ♥ s♥t ♦♥t♦♥ ♦r ♣♦♥t st t♦

♥ ♥② tr♥t♦♥ ♦ T3c ♦r♠ ♥ t s♦♥ ♣rt sss ♦

t♦ t ♣♦♥t sts tt ♦ ♥♦t ♥ ♥② tr♥t♦♥ ♦ T3c

♥t♦♥

t s r tt tr♥t♦♥ ♦ ♣♦♥t st S ♥ E3 s s♠♣ ♦♠♣① t rt①

st S t s ♥② tr♥t♦♥ ♥ ♦♥② ttrr♦♥ stss t ♥②♣r♦♣rt② ts r♠sr♥ ♦s ♥♦t ♦♥t♥ ♥② ♣♦♥t ♦ S ♥ ts ♥tr♦r r♦♠♥♦ ♦♥ ②s ss♠ ♥② tr♥t♦♥s ♦ E

3 t♦ ♥q② ♥ ②s♥ s②♠♦ ♣rtrt♦♥ s sr ♥ t♦♥

❲ ♥t t♦ ♥ t ♥② tr♥t♦♥ ♦ T3c ♦r ♥ ♣♦♥t st π(S)

s t♦ s t ♣r♦t♦♥ ♥r π ♦ ♥② tr♥t♦♥ ♦ E3 ♥ ② t

♥♥t ♣r♦ ♣♦♥t st GS := ϕc(S × Z3) ❲t♦t ♦ss ♦ ♥rt② ♥ ss♠

tt t ♣♦♥ts ♦ S ♥ Dcr♦♠ ♥♦ ♦♥ ♥ ②s ♥♦t t tr ♦♥t♦♥s ♦ ♥t♦♥

♠♣ ♦♠♣①

♠♠ ♦r ♥② ♥t ♣♦♥t st S ⊂ Dc st ♦ s♠♣s K ♥ E3 tt s

♥ t ♥② ♣r♦♣rt② t rs♣t t♦ GS s s♠♣ ♦♠♣① ♥ E3

Pr♦♦ ❲ ♥ t♦ s♦ tt K s t ♦ ♥t♥ss ♣r♦♣rt② ss♠ tt tr s rt① v t ♥ ♥♥t ♥♠r ♦ ♥♥t s♠♣s ♥ ts

♥ ♥♥t ♥♠r ♦ ♥♥t s ♥ S ♦♥t♥s ♦♥② ♥t ♥♠r ♦ ♣♦♥ts tr♠st t st ♦♥ ♣♦♥t q ♥ S ♦ ♥♥t② ♠♥② ♣r♦ ♦♣s r ♥t t♦v ♣r♦ ♦♣s ♦ q ♦r♠ r ♥ t ♠tr ♦ t rst ♠♣t② s♦♥ ② ‖c‖ ♦ r♠sr♥ s ♦ ttrr tt r ♦s ♦ s t♥v ♥ ♣r♦ ♦♣s ♦ q tt r rtr ② t♥ ‖c‖ ♥♥♦t ♠♣t② s s ♦♥trt♦♥ ♥ ♥ rts ♥ K r ♥♥t t♦ ♦♥② ♥t ♥♠r ♦ s♠♣s

t s ♥♦ ♦♥sr ♣♦♥t p ♥ E3 tt s ♥♦t rt① ♥ K t s ♥ t ♥tr♦r

♦ ttrr♦♥ t♥ t s ♥♦r♦♦ tt ♥trsts ♦♥② ♦♥ s♠♣① t s ♥t ♥tr♦r ♦ tr♥ t♥ t s ♥♦r♦♦ tt ♥trsts tr s♠♣s ttr♥ ♥ t t♦ ♥♥t ttrr ss♠ ♥♦ tt p s ♥ t ♥tr♦r ♦ ♥

Page 35: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

Pr♦ tr♥t♦♥s

t♥ t s ♥♦r♦♦ ♥trst♥ ♦♥② t tr♥s ♥ ttrr tt r ♥♥tt♦ t t♦ ♥♣♦♥ts ♦ t ♦r♥ t♦ t ♦ sss♦♥ ts r ♦♥② ♥t②♠♥②

♥ GS ♦♥t♥s ♣♦♥ts ♦♥ ♥ ♥♥t r ♥② ♣♦♥t p ∈ E3 s ♦♥t♥ ♥ s♦♠

s♠♣① ♥ ② ♣♦♥ts ♥ GS ♦tr t ♠♠ ts ♠♣s tt t st♦ s♠♣s t ♣♦♥ts ♦ GS s rts ♥ rs♣t♥ t ♥② ♣r♦♣rt② s ♥② tr♥t♦♥ ♦ E

3 ♥ ♥♦t t ② DT (GS) ❯s♥ π ♥ ♥♦ ♥t ♥② tr♥t♦♥ ♦ T

3c

♥t♦♥ ♥② tr♥t♦♥ ♦ T3c t DT (GS) ♥② tr♥t♦♥

♦ GS ♥ E3 π(DT (GS)) s s♠♣ ♦♠♣① ♥ T

3c t♥ t ♥②

tr♥t♦♥ ♦ T3c ♥ ② S ♥ ♥♦t t ② DTT(S)

r r ♣♦♥t sts ♦r π(DT (GS)) s ♥♦t s♠♣ ♦♠♣① s r ♦♥ ♣

rst ♦ ts st♦♥ s ♦t t♦ st②♥ ♥ S t② ♥s ♥②tr♥t♦♥ ♦ T

3c ❲ s♦ tt ♥t♦♥ t② ♠s s♥s ❲ r② tt

t s♠♣s ♠t ♥r π tt ♣r♦ ♦♣s ♦ s♠♣① ♥ DT (GS) r♠♣♣ ♦♥t♦ t s♠ s♠♣① ♥ T

3c ♥r π ❲ s♦ ♣r♦ tt π(DT (GS)) s

st ♦ s♠♣s t♥ t s ♦♥t♦♥s ♥ ♥② sss ♥r r♠st♥s ♦♥t♦♥ s ②s t ♥ssr② ♥ s♥t ♦♥t♦♥♦♥ π(DT (GS)) t♦ tr♥t♦♥ ② ♥t♦♥ t s s♠♣ ♦♠♣①♦s ♥♦♥ s ♦♠♦♠♦r♣ t♦ T

3c

t s strt t t rst ♠♠

♠♠ t rstrt♦♥ ♦ π t♦ ♥② s♠♣① ♥ DT (GS) s ♥t t♥ π(DT (GS))s st ♦ ♥tr♥② s♦♥t s♠♣s ♥ T

3c tt ♦ ♥♦t ♦♥t♥ ♥② ♣♦♥t ♦ π(S) ♥ tr

♥tr♦r

Pr♦♦ ♦♥sr ttrr♦♥ σ ♦ DT (GS) ♦s rts r ♦rt♣ ♦ ♣♦♥tsPσ ⊂ GS σ stss t ♥② ♣r♦♣rt② s♦ ♣r♦ ♦♣s ϕc(Pσ × Z

3) s♦ ♥ ♠♣t② r♠sr♥ s s♦s tt ts ♣r♦ ♦♣s ♦r♠ ttrr ♦DT (GS)

♦t tt ts s ♥ tr ♥ ♥rt ss ♥ ♥rs s ♥ ❬❪t♥ t ♥② tr♥t♦♥ ♦ st ♦ ♦s♣r ♣♦♥ts ♦♥② ♣♥s ♦♥ tr ①♦r♣ ♦rr s tr♥st♥ t st ♦ ♣♦♥ts ♦s ♥♦t ♥ tr ①♦r♣ ♦rr ♣r♦ ♦♣s ♦ tt ♣♦♥t st r tr♥t ♥ t s♠ ②

♦♦♥② π ♦♣ss ♣rs② t ♣r♦ ♦♣s ♦ σ ♦♥t♦ ts q♥ ss♥ T

3c s ♥② ♦r♠♥s♦♥ s♠♣① ♥ DT (GS) s ♥♥t t♦ s♦♠ ttrr♦♥ ♥

ts s ♥ ② sst ♦ ts rts t s♠ ♦s ♦r s♠♣s ♦ ♥② ♠♥s♦♥♦ t ♣r♦t♦♥s ♥r π ♦ t♦ ♥tr♥② s♦♥t k♠♥s♦♥ s♠♣s σ ♥

τ ♥ DT (GS) r tr q ♦r ♥tr♥② s♦♥t ♦r k ≥ 1 t♦ t tt② ♦ πt♥ ♦t s♠♣s ♥ tr rs♣t ♠s s♠ r♠♥t ♠♣s tt t♥tr♦r ♦ s♠♣① ♥♥♦t ♦♥t♥ ♥② rt①

❲ ♦sr tt π(DT (GS)) s ♥t DT (GS) s ♦② ♥t ♠♠ t str ♦ ♥② rt① s ♥t s S s srt s♦ GS s srt ♥ ttrr rt♥ ♦♠ rr t♥ s♦♠ ♦♥st♥t ♦♦♥② tr r ♦♥② ♥t② ♠♥②

Page 36: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥② tr♥t♦♥ ♦ T3c

ttrr ♥ssr② t♦ t ♦r♥ ♦♠♥ Dc ♥ ts T3c ♥t② ♠♥② ttrr

♦♥② ♥t② ♠♥② s s♦ t ♦r ♥♠r ♦ s♠♣s ♥ π(DT (GS)) s ♥tt♦♦

♦ r ♥♦ tt s♠♣s ♥ DT (GS) r ♠♣♣ s s♠♣s ♦♥t♦ T3c t♥

t ♦ tr♥t♦♥ s ♠♣♣ ♦♥t♦ st ♦ s♠♣s ♥ T3c ❲ ♥♦ ♦♥sr t

♥♥ rt♦♥

srt♦♥ ss♠ tt t rstrt♦♥ ♦ π t♦ ♥② s♠♣① ♥ DT (GS) s ♥t τ s s♠♣① ♥ π(DT (GS)) ♥ τ ′ ≤ τ t♥ τ ′ s s♠♣① ♥ π(DT (GS)) s♦♦s ♠♠t② r♦♠ t t tt ♥♥ rt♦♥s r ♠♥t♥ ② π ♥ r♦♠♠♠

t ♦♥② r♠♥s t♦ s♦ ♦♥t♦♥ t ♥trst♦♥ ♦ t♦ s♠♣s σ ♥ τ ♥π(DT (GS)) s ♥♦tr s♠♣① χ tt s ♥♥t t♦ ♦t σ ♥ τ

♠♠ ss♠ tt t rstrt♦♥ ♦ π t♦ ♥② s♠♣① ♥ DT (GS) s ♥tt σ, τ ∈ π(DT (GS)) ♥② t♦ s♠♣s ♥ T

3c t♥ σ ∩ τ s st ♦ s♠♣s ♥

π(DT (GS))

Pr♦♦ ❲t♦t ♦ss ♦ ♥rt② ss♠ tt σ ∩ τ 6= ∅ ❲ s♦ tt σ ∩ τ =⋃p∈σ∩τ χp r χp s s♠♣① ♥ π(DT (GS)) ♥♦♥ s ♥t s tr r

♦♥② ♥t② ♠♥② s♠♣s ♥ π(DT (GS)) ♦♥sr ♣♦♥t p ∈ σ ∩ τ p s rt①♦ π(DT (GS)) t♥ t s ♥♦t ♦♥t♥ ♥ t ♥tr♦r ♦ ♥② ♦tr s♠♣① ♦r♥ t♦♠♠ ♥ st χp = p p s ♥♦t rt① ♥ π(DT (GS)) t♥ p ∈ σ′ ♥p ∈ τ ′ ♦r s♦♠ ♣r♦♣r s σ′ ≤ σ ♥ τ ′ ≤ τ s σ ♥ τ r ♥tr♥② s♦♥t♠♠ ♥ σ′ ♥ τ ′ r ♥ tr ♥tr♥② s♦♥t ♦r ♥t t ♦♦stt t② r t s♠ ♥ st χp := σ′ = τ ′ ② ♦♥t♦♥ t s♠♣① χp s♦♥t♥ ♥ π(DT (GS))

♠♠r tt⋃t(v) ♥♦ts t ♥♦♥ ♦ t s♠♣s ♥ t str ♦ v ❲ ♥

♥♦ ♦r♠t t ♦♦♥ s♥t ♦♥t♦♥ ♦r π(DT (GS)) t♦ s♠♣ ♦♠♣①

♠♠ ♦r rts v ♦ DT (GS) t rstrt♦♥ ♦ t ♣r♦t♦♥ ♠♣ π|S t(v)

s ♥t t♥ π(DT (GS)) ♦r♠s s♠♣ ♦♠♣①

Pr♦♦ ❲ st K = π(DT (GS)) t σ s♠♣① ♦ DT (GS) ♥ v ♥ ♥♥t rt①♥ σ ⊆ ⋃

t(v) ts t rstrt♦♥ ♦ π|S t(v) t♦ σ s ♥t s ♥ K s st♦ s♠♣s ♠♠

♦♥t♦♥s ♥ ♦♦ r♦♠ t ♦ sss♦♥ t r♠♥s t♦ s♦ ♦♥t♦♥ ♦♥sr t♦ s♠♣s σ, τ ∈ K t σ ∩ τ 6= ∅ ② ♥t♦♥ ♦ s♠♣① tr①st sts Pσ,Pτ ♥ Dc × Z

3 s tt σ = π((Pσ)) ♥ τ = π((Pτ )) r♦♠ ♠♠ ♥♦ tt σ ∩ τ s st ♦ s♠♣s ♥ K ♦ tr ①sts rt① v ∈ σ ∩ τ♥ σ, τ ∈ t(v) ② ss♠♣t♦♥ π|S t(v) s ♥t s♦ π s ♥t ♦♥ σ ♥ τ ♥σ ∩ τ = π((Pσ)) ∩ π((Pτ )) = π((Pσ ∩ Pτ )) s♦ t rstrt♦♥ ♦ π|S t(v) t♦(Pσ ∩Pτ ) s ♥t ♦ r♦♠ ♥t♦♥ t ♦♦s tt σ ∩ τ s s♠♣① ♥σ ∩ τ ⊆ σ, τ σ ∩ τ ≤ σ, τ

s t st ♥r♥t ♦r t t♦r♠ ♥ t ♦♦♥ ♠♠ tt s♦s ttt ♥② tr♥t♦♥ s ♥ ♥ ♥t♦♥ s t② tr♥t♦♥ ♦ T

3c

♥ t s♥s ♦ ♥t♦♥

Page 37: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

Pr♦ tr♥t♦♥s

♠♠ |π(DT (GS))| s ♦♠♦♠♦r♣ t♦ T3c

Pr♦♦ ② ts ♦♥strt♦♥ |DT (GS)| = E3 ♥ π s srt ♦♦♥② π(|DT (GS)|)

s q t♦ T3c ♥ t ♥ ♦ qts

π(|DT (GS)|) = π

σ∈DT (GS)

σ

(1)

= π

τ∈π(DT (GS))

π−1(τ)

(2)=

τ∈π(DT (GS))

τ =⋃

σ∈DT (GS)

π(σ) = |π(DT (GS))|

♦s t t ♦♦♥ r♠♥ts

s st♣ st rr♦♣s t s♠♣s ♥ r♥t ♦rr t ♦s ♥♦t ♥ t st ♠♠

r s ♦♥② ♥t ♥♠r ♦ ♠♥ts ♥ π(DT (GS))

❲ r ♥♦ r② t♦ ♣r♦ t ♠♥ t♦r♠ ♦ ts st♦♥ s ♥ssr②♥ s♥t ♦♥t♦♥ ♦r π(DT (GS)) t♦ tr♥t♦♥ ♦ T

3c t s r tt t

st♦♥ ♦ s♠♣ ♦♠♣① s t s♦♠♣① tt ♦♥ssts ♦ s ♥ rts

♦r♠ ss♠ tt t rstrt♦♥ ♦ π t♦ ♥② s♠♣① ♥ DT (GS) s ♥tπ(DT (GS)) s tr♥t♦♥ ♦ T

3c ♥ ♦♥② ts st♦♥ ♦s ♥♦t ♦♥t♥ ♥② ②

♦ ♥t ss t♥ ♦r q t♦ t♦

Pr♦♦ ❲ rst s♦ t ♣rt ❲ st K = π(DT (GS)) r♦♠ ♠♠ ♥srt♦♥ ♥♦ tt K s ♥t st ♦ s♠♣s tt s ♦♥t♦♥s ♥ ss♠ tt K s ♥♦t s♠♣ ♦♠♣① r♦♠ ♠♠ tr s rt①v ∈ K ♦r π|S t(v) s ♥♦t ♥t s ♠♣s t ①st♥ ♦ t♦ r♥t ♣♦♥tsp, q ∈ ⋃

t(v) t π(p) = π(q) t σ ♥♦t t s♠♣① ♦ K tt ♦♥t♥s π(p) = π(q)♥ ts ♥tr♦r ♥ tr r t♦ r♥t s♠♣s σ′

E∈ π−1(σ) ♥ σ′′

E∈ π−1(σ)

♦♥t♥♥ p ♥ q rs♣t② s σ′E♥ σ′′

Er ♦t ♠♥ts ♦ t(v) t u, w

rts r♥t r♦♠ v t u ≤ σ′E♥ w ≤ σ′′

Es tt π(u) = π(w) rts

u ♥ w ②s ①st s π(σ′E) = π(σ′′

E) rts u, w r s♦ ♠♥ts ♦ t(v)

♥ ts tr r s (u, v) ♥ (v, w) ♥ DT (GS) r♦♠ π(u) = π(w) ♦♦s tt t♣r♦t♦♥ ♦ (u, v) ♥ (v, w) ♥r π ♦r♠s ② ♦ ♥t t♦ ♥ T

3c ♦♥trts

t ss♠♣t♦♥ tt π|S t(v) s ♥t ♦ K ♠st s♠♣ ♦♠♣① ♦♦♥♥t♦♥ ♥ ♥♦ ♥♦t DTT(S) = π(DT (GS)) ♠♠ s♦s tt DTT(S)s t② tr♥t♦♥ ♦ T

3c ♦♥s t rst ♣rt ♦ t ♣r♦♦

♦ ♦♥sr t ♦♥② ♣rt r ♥♥♦t ♥② ②s ♦ ♥t ♦♥ s♦ t ss♠♣t♦♥ tt t rstrt♦♥ ♦ π t♦ ♥② s♠♣① ♥ DT (GS) s ♥t ss♠π(DT (GS)) s s♠♣ ♦♠♣① ♦♥t♥♥ t♦ s σ ♥ τ σ 6= τ tt ♦r♠ ②♦ ♥t t♦ ♥ σ∩ τ ♦♥ssts ♦ t t♦ ♥♣♦♥ts ♦ t s♠♥ts σ ♥ τ ♦♥♦t ♦r♠ s♠♣① ♥ π(DT (GS)) ♦♥trts ♦♥t♦♥ ♦ ♥t♦♥

r ♦r ♥ strt♦♥ ♦ ♠♠ ♥ ♦r♠

Page 38: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥② tr♥t♦♥ ♦ T3c

r strt♦♥ s r♦♥ s ϕc(t(p) × Z3) ∩ Dc ♠♠

r r sr ②s ♦ ♥t t♦ ♦r♥t♥ r♦♠ p ♦r♠

♥ t ♣r♦♦ ♦ ♦r♠ s♦♥ tt π|S t(v) s ♥♦t ♥t t♥tr r ②s ♦ ♥t t♦ ♥ π(DT (GS)) s q♥t t♦ π(DT (GS)) ♥♦t ♥ s♠♣ ♦♠♣① ♦♦♥② ts ♦♥t♦♥ s ♥♦t ♦♥② s♥t t s♦ ♥ssr②♥ ♠♠

P♦♥t sts tt ♦ ♥♦t ♥ ♥② tr♥t♦♥ ♦ T3c

♥ ts st♦♥ ①♣♥ ♦ ♥ ♥t r♣rs♥tt♦♥ ♦ t ♣r♦ tr♥t♦♥ DT (GS) tt s s♠♣ ♦♠♣① ♥ π(DT (GS)) s ♥♦t s♠♣ ♦♠♣① S ♦s ♥♦t ♥ ♥② tr♥t♦♥ ♦ T

3c ♦♠♣t ♥ ♥t② st ♦r♥

s♣ s t♦♥ ♦t tt E

3 ts t t ♣r♦t♦♥ ♠♣ π s ♦r♥ ♠♣ s ♥rs ♦r♥s♣ ♦ T

3c ♠♥s tt t s ♦r♥ s♣ ♦r ♦r♥ s♣s ♦ T

3c ❬r♠❪

♦r ♥♥♦t s t t♦ ♦♠♣t t ♥② tr♥t♦♥ s t s ♥ ♥♥t♥♠r ♦ sts ❲ ♥♦ ♦♥strt ♥t② st ♦r♥ s♣ tt s s♥t②r s♦ tt ♥② ♣♦♥t st P ♥s ♥② tr♥t♦♥ ♦ t

t h = (hx, hy, hz) ∈ N3 T

3h∗c s ♦r♥ s♣ ♦ T

3c t♦tr t t ♦r♥

♠♣ ρh := π π−1h

r πh : E3 → T

3h∗c ♥♦ts t ♣r♦t♦♥ ♠♣ ♦ T

3h∗c s ρ−1

h(p)

♦r ♥② p ∈ T3c ♦♥ssts ♦ hx ·hy ·hz r♥t ♣♦♥ts T

3h∗c s hx ·hy ·hzst ♦r♥

s♣ ♦r♥ ♦♠♥ s Dh∗c = [0, hxcx) × [0, hycy) × [0, hzcz) hx = hy = hz s t ♥♦tt♦♥ πh := πh t h := hx ·hy ·hz ♦r π27 ♥ ♦r♠ ♦ ♦ttt T

3h∗c s t t♦rs ♥

♦♥ ♥ s♦♥ ❬❪ s♦ tt ♦♥② t ♣♦♥ts ♦ GS ♦♥t♥ ♥ Dc ♥t ♦♣s tt srr♦♥ t ♥ ♥ ♥♥ ♦♥ t s♠♣s tt r ♦♠♣t②♦♥t♥ ♥ Dc ❲ s t s ♦ tr ♣r♦♦ t♦ ♣r♦ ♦r♠ s♦ rst st ♦ tr ♣♣r♦ ♣r♦♦ s s ♦♥ ♦♥sr♥ ♣rts ♦ ttr♥t♦♥ ♥ ♥♥ ② ♣♦♥t s s ♦♥ ♥ tr st♣s s♥ ♥♦ss♠s ❬❪ t F (1) ♥♦t t ❱♦r♦♥♦ ♦ t ♦r♥ ♥ t ❱♦r♦♥♦ r♠ ♦t ♦rt ♦ t ♦r♥ ♥r G ♥ F (1) s ♥♠♥t ♦♠♥ ♦ G t rtr♠♦rQ ♣♦♥t st ♥ F (1) A ⊕ B ♥♦ts t ♥♦s s♠ ♦ A ♥ B ♥ ♥F (i) := F (1) ⊕ F (i−1)

Page 39: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

Pr♦ tr♥t♦♥s

♠♠ ❬❪ t σ ♥ τ s♠♣s ♥ t ♥♥t ♣r♦ ♥② tr♥t♦♥ DT (GQ) s tt ♦♥ ♦ t rts ♦ σ s ♥ t ♥tr ♦ F (1) ♥ τ∩F (1) 6= ∅♦s ♥

t ♥tr ♦ t r♠sr♥ ♦ σ s ♥ F (1)

σ s ♦♠♣t② ♦♥t♥ ♥s F (2)

τ s ♦♠♣t② ♦♥t♥ ♥s F (3)

Pr♦♦ ❲ r② st t ♣r♦♦s ♦ t tr ♣r♦♣rts

s ♦♦s rt② r♦♠ t t tt F (1) s ❱♦r♦♥♦ ♦ t ❱♦r♦♥♦ r♠♦ t ♦rt ♦ t ♦r♥ ♥r t t♦♥ ♦ G t ♥tr ♦ t r♠sr♥ ♦ σ s ♦ts ♦ F (1) t♥ t ♦ ♦sr t♦ s♦♠ ♦tr ♣♦♥t ♦ GQ♦♥trt♥ t t tt t s t ♥tr ♦ t r♠sr♥ ♦ σ

s ♦♦s rt② r♦♠ ♥ r♦♠ t t tt F (2) s t ♥♦s s♠ ♦F (1) t ts

s ♦♦s rt② r♦♠ t ♥t♦♥ ♦ F (3)

r ♦r ♥ strt♦♥ ♦ ♠♠

r strt♦♥ t s s♥t t♦ ♦♥sr F (3) ♥ ♦rr t♦ ♦♠♣t ♥②tr♥t♦♥ ♦ t t t♦rs

r♦♠ ♠♠ ♦♦s tt tr♥s ♦ t ♣r♦ ♥② tr♥t♦♥ ♦ Qr ♦♥t♥ ♥s F (3) ♥ s♦ t s s♥t t♦ ♦♠♣t t ♥t ♥② tr♥t♦♥DT (GQ ∩ F (3)) ♥ E

3 ♦r♥ t♦ ♠♠ s♠♣s ♦ DT (GQ ∩ F (3)) tt t st ♦♥ rt① ♥ F (1) r s♠♣s ♦ t ♥♥t ♣r♦ ♥② tr♥t♦♥DT (GQ) ♥ t st ♦ ts s♠♣s ♦rs F (1) ♣♣②♥ t t♦♥ ♦ G ♦♥ t ②s♥ ♥♥t ♣r♦ ♣rtt♦♥ ♦ E

3 ♦t tt ts rst rt② ①t♥s t♦ Ed

❯s♥ t ♣♣r♦ ♦ t ♣r♦♦ ♦ ♠♠ ♥ s♦ t ♦♦♥

♦r♠ π27(DT (GS)) s s♠♣ ♦♠♣①

Pr♦♦ ❲ s♦ tt tr r ♥♦ ②s ♦ ♥t ♥ π27(DT (GS)) t Dc(i, j, k) ♥♦tt tr♥st♦♥ ♦ Dc ② (i · cx, j · cy, k · cz)

Dc(i, j, k) := [i · cx, (i + 1) · cx) × [j · cy, (j + 1) · cy) × [k · cz, (k + 1) · cz).

Page 40: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♦rt♠

ss♠ tt tr s ② ♦ ♥t t♦ ♥ π27(DT (GS)) ♥ tr r rtsv, v′, v′′ ∈ DT (GS) s tt t s (v, v′) ♥ (v′, v′′) (v, v′) 6= (v′, v′′) r ♦♥t♥ ♥DT (GS) ♥ tt π27(v) = π27(v

′′) t Dc(i, j, k),Dc(i′, j′, k′) ♥ Dc(i

′′, j′′, k′′) ♥♦tt tr♥st♦♥s ♦ Dc tt ♦♥t♥ v, v′ ♥ v′′ rs♣t② ♦r♥ t♦ ♠♠ s♠♣① ♥trsts ♦t Dc(i, j, k) ♥ Dc(i

′, j′, k′) t♥ |i − i′| ≤ 1 |j − j′| ≤ 1 ♥|k−k′| ≤ 1 ❲t♦t ♦ss ♦ ♥rt② ♥ ♦♦s v ♥ v′ s tt (i, j, k), (i′, j′, k′) ∈0, 13 ♦t tt π27(Dc(i, j, k)) = π27(Dc(i mod 3, j mod 3, k mod 3)) s♦ t st ♦♥♦ t i′′, j′′ ♥ k′′ ♠st ♥ 0 − 3, 1 − 3, 0 + 3, 1 + 3 ♦r π27(v) = π27(v

′′) t♦ ♦s s ♥♦t ♣♦ss ♦r♥ t♦ ♠♠

❲t t s♠ r♠♥tt♦♥ s ♥ t ♣r♦♦ ♦ ♠♠ |π27(DT (GS))| s ♦♠♦♠♦r♣ t♦ t st ♦r♥ s♣ T

3h∗c t h = (3, 3, 3) s ♦♠♦♠♦r♣

t♦ T3c❲ ♣rr t♦ s t r♠♦r ♦ ♦r♥ s♣s rtr t♥ st t ♦t ♦♣s

♦ t ♣♦♥ts s ♥ ❬❪ s t ♦s rt♥ rt ♦♥rs ♥ t tstrtr t ♥② rt♦♥s r ♦♠♣t ♦r s♠♣s

s s♥ ♥ t ♥①t st♦♥ t ♥r♠♥t ♦rt♠ tt ♣rs♥t rqrs st② str♦♥r rst t♥ ♦r♠

♦rt♠

s ♠♥t♦♥ ♥ t ♥tr♦t♦♥ tr s str♦♥ ♠♦tt♦♥ ♦r rs♥ t st♥r♥r♠♥t ♦rt♠ ❬♦❪ t♦ ♦♠♣t ♣r♦ ♥② tr♥t♦♥ t s r♦ st ♦ t ♦rt♠ tt ♣r♦♣♦s ♦r ♣rs♥t t ♥ ♠♦r t tr

• ❲ strt ♦♠♣t♥ ♥ ♥t②st ♦r♥ s♣ T3h∗c ♦ T

3c t h ♦s♥

s tt πh(DT (GS)) s r♥t t♦ tr♥t♦♥♦r♠ s♦s tt s ♦r♥ s♣ ②s ①sts h = (3, 3, 3) s♦♥ ♣♦ss ♦ ♥ t t ♦rt♠ rqrs st② str♦♥r rst t♥♦r♠ ♥ ts ♥s t♦ s ♦tr ♦r♥ s♣s Dc s ♥♦t

• ♥ ♣rt t ♣♦♥t st s r ♥ rs♦♥② strt t s ② tttr ♥ ♥srt t ♣♦♥ts ♦ sst S ′ ⊂ S t ssq♥t π(DT (GS ′′))♦r S ′ ⊂ S ′′ ⊆ S r s♠♣ ♦♠♣①s ♥ T

3c

♥ ts s sr ♣r♦ ♦♣s ♦ s♠♣s ♦ πh(DT (GS ′)) ♥ stt♦ ♦♠♣t♥ π(DT (GS)) ♥ T

3c ② ♥ t ♣♦♥ts t ♥ S \ S ′

♥ ts ② ♥ ❬❪ ♦ ♣t♥ ♣♦♥ts s s♦♦♥ s ts s ♣♦ss ♥ss ♥ S s s♠ ♦r ② strt ♣♦♥t st t ♦rt♠ ♥r ♥trs t s♦♥♣s ♥ rtr♥s πh(DT (GS)) s tr♥t♦♥ ♦ T

3h∗c st ♦♠♦♠♦r♣ t♦

T3ct♦♥ s ♦r♥③ s ♦♦s ❲ sr t ♦rt♠ ♦r t rstrt s

♥ Dc s ♥ ♣r♦ ts ♦rrt♥ss s ♦rrs♣♦♥s t♦ t t rr♥t ♠♣♠♥tt♦♥ ♣r♦s ♥ t s♦♥ ♣rt r① t ♦♥t♦♥ ♦♥ Dc ♦♥t t♦ ♦ ♥ sr ♦ t ♦rt♠ ♥ ♣t t♦ ts s ♥②♥ t♦♥ s♦ ♦ t♦ ①t♥ t ♦rt♠ t♦ ♦♠♣t t ♥②tr♥t♦♥s s

Page 41: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

Pr♦ tr♥t♦♥s

♦t tt ♦r st♥ t♦ ♦♠♣t♥ ♥ T3c t s ♥♦t s♥t t♦ tst tr

π(DT (S ′c)) s s♠♣ ♦♠♣① ♥ ♥ ♣♦♥t ♦ rt ② ♦ ♥tt♦ s r ♦ str♦♥r ♦♥t♦♥ s ♥ ♦r t st

r strt♦♥ ♥ ♣♦♥t ♥ s♠♣ ♦♠♣① ♥ rt ② ♦♥t t♦

♦♦♥ ♦srt♦♥ s ♥ t ssq♥t ♣r♦♦s

srt♦♥ t ∆ ♥♦t ttrr♦♥ ♥ DT (GS) ♥ B∆ ts r♠sr♥ t ♠tr ♦ B∆ s s♠r t♥ cmin := mincx, cy, cz t♥ π|B∆

s ♥t♥ π|∆ s ♥t s s♥ ∆ ⊂ B∆ s ∆ s s♠♣① ♥ T

3c

♦♠♥

t ♦r♥ ♦♠♥ Dc s t ♥t c t ♥r♠♥t ♦rt♠ sst st ♦r♥ s♣ T

33c r 3c = (3c, 3c, 3c) ♦r♥ ♦♠♥ ♦r ts

♦r♥ s♣ s D3c❲ ♣r♦ ♦ tt ♦♥ s ♥ t tr♥t♦♥ ♦ T

33c

r s♦rtr t♥ 1√6c

♦♠♣t♥ s♠♣ ♦♠♣① ♥ T3c s ♣♦ss

♦rt♠ ♦r ♣s♦♦ st♥ ♦ t ♦rt♠ t ♦♠♣ts tr ♥② tr♥t♦♥ ♦ T

3c s ♥ ♥ ♥t♦♥ ♦r ♥② tr♥t♦♥

♦ T33c s st ♦♠♦♠♦r♣ t♦ T

3c

♦ s♦ t ♦rrt♥ss ♦ t ♦rt♠ t r♠♥s t♦ sts t ♦♦♥ t♦♣r♦♣rts

tr ♥srt♦♥ 27 s ♥② tr♥t♦♥ ♦ T33c t s ♠♣s③ ♦♥

t t tt ♦r♠ ♥♥♦t s r s ♥ t ♥♥r ♦♦♣ st♣ t st ♦ ♣♦♥ts ♣rs♥t ♥ 27 ♦s ♥♦t ♦♥t♥ t ♣r♦ ♦♣s ♦ pt p ♣♦♥t ♥ Dc ♥ Tp ⊆ ϕc(p×Z

3)∩D3c Tp s sst ♦ t r ♦ ♦♣s ♦ p tt t♥ D3c ♥ 27 s ②s ♦ t ♦r♠ π27(DT (GS ∪T 3c

p ))t T 3c

p = ϕ3c(Tp × Z3) ♠♠ s♦s tt ts s tr♥t♦♥

s ♥ π27(DT (GS)) r s♦rtr t♥ 1√6c t♥ ♥ st t♦ ♦♠♣t♥

♥ T3c rtr♦♥ ♦r ♣r♦♦

Page 42: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♦rt♠

♦rt♠ ♦♠♣t ♥② tr♥t♦♥ ♦ T3c r♦♠ ♣♦♥t st

♥♣t t S ♦ ♣♦♥ts ♥ Dc ♦ ♥t c ∈ E3 \ 0

t♣t DTT(S) ♣♦ss ♦trs π27(DT (GS)) S ′ ⇐ S P♦♣ p r♦♠ S ′

S ⇐ p 27 ⇐ π27(DT (ϕc(p × Z

3))) ♥ ♣r♦♠♣t

t ♦♥st ♥ 27 s ♦♥r t♥ 1√6c ♦

P♦♣ p r♦♠ S ′ S ⇐ S ∪ p ♦r p′ ∈ p + c ∗ ζ | ζ ∈ 0, 1, 23 ♦ ♥srt p′ ♥t♦ 27

♥ ♦r 27 = π27(DT (GS)) S ′ = ∅ t♥ rtr♥ 27 = π27(DT (GS)) ♥♦♥tr♥

♣♦♥t st

♦♠♣t DTT(S) r♦♠ 27 st t♦ T3c

♥srt ♣♦♥ts r♠♥♥ ♥ S ′ ♥t♦ DTT(S) ♦♥ ② ♦♥ rtr♥ DTT(S)

♠♠ t S ⊂ Dc ♥t ♣♦♥t st p ∈ Dc ♣♦♥t ♥ Tp sst ♦ϕc(p × Z

3) ∩ D3c Dc s t♥ π27(DT (GS ∪ T 3cp )) s tr♥t♦♥ ♦ T

33c

t T 3cp := ϕ3c(Tp × Z

3)

Pr♦♦ ❲ rst ♦♥sr tr♥t♦♥ ♥ ② ♦♥② ♦♥ ♣♦♥t S = q ♦r s♦♠q ∈ Dc ♥ π27(GS) ♦♥ssts ♦ 27 ♣♦♥ts rr♥ s rr r ❲t♦t ♦ss ♦♥rt② ♥ ss♠ q = (0, 0, 0) s tr♥t♦♥s ♦ ♣♦♥t sts r ♥r♥tt rs♣t t♦ tr♥st♦♥s ♣♦♥t st π27(GS) s ② ♥rt r r r♥t ♠♣t② s tt t ♣♦♥ts ♦♥ tr ♦♥r② ② r ♥tr t((

12 , 1

2 , 12

)+ ζ

)∗ c t ζ ∈ 0, 1, 23 ♥ rs r =

√3

2 c ≈ 0.866 c ❲t♦t ♦ss ♦♥rt② ♥♦ ♦♥sr t B ♥tr t

(12 , 1

2 , 12

) t s s② t♦ tt t

♥trst♦♥ ♦ t ♠ ♦ ♥② ♣r ♦ ts s ♥r π27 ♦♥ssts ♦ ♦♥ ♦♥♥t st tt π27 rstrt t♦ t ♥♦♥ ♦ ♥② ♣r ♦ ts s s ♥t

s t ♥t ♦ ♥ ♦ t D3c s 3c ♥ t ♠tr ♦ B s√

3 c ♥ ♦♥t (3 −

√3) c ♦ ♥♦ t♦ ♥tr♦ ② ♦ ♥t t♦ t B′ rst

♠♣t② ♥ ② t ♣♦♥ts (2, 0, 0) (2, 0, 1) (2, 1, 0) (2, 1, 1) ♥(

1+√

32 , 1

2 , 12

) t

tr♥s ♦t tt t rs ♦ B′ s s♠r t♥ 0.712 c r ①st ♦tr s s ♦♥t y ♥ z①s t s♥ Dc s tr r r t s♠ t ♦ t ♦r♣t♥ B ♥ B′ s ss t♥ (2 ·0.712+

√3−3)c < 0.155 c ♥ π27|B∪B′ s ♥♦t ♥t

♥ π27(B ∩ B′) ♦♥ssts ♦ t♦ s♦♥t ♦♥♥t ♦♠♣♦♥♥ts♦ t♦ ①♣♦t s♣ ♣r♦♣rt② ♦ ♦rt♠ π27(GS) ♦♥ssts ♦

rr ♦rt♦♦♥ r ♦ ♣♦♥ts ♥ π27(T 3cp ) s sst ♦ t r ♦ ♦♣s ♦ p

r♦♠ ts ♥♦ tt tr ♥ ♣♦♥t p1 ∈ T 3cp t ♥①t ♣♦♥t r ② s♦♠

t♦r ♥ c∗Z3 ♦r t♦ t♦ ♦r♠ ② ♦ ♥t t♦ r♦ss♥ t s B ♥ B′

ts ♥t ♦♥ ♦♥ ①s ♦ t♦ t♥ 1.266c ♥ 1.424c s s ♥♦t ♣♦sss [1.266, 1.424] ∩ Z = ∅ s r ♦t tt ♠♦ p1 ♥s B t♥ trs ♦ B′ ♦♠s s♠r ♥ ts t ♦r♣ r♥ s ♦♥② sst ♦ [1.266, 1.424]

Page 43: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

Pr♦ tr♥t♦♥s

r ♦ ♣r♦ ♦♣② ♦ p1 ♥ ♥s B ∩ B′

r s ♥♦ rtr ♣♦sst② ♦r ② ♦ ♥t t♦ t♦ ♦r s t s♦rtst♦♥s tr♦ D3c ♥t

√18 c s rr t♥ 2

√3c

❯s♥ ♦r♠ ts ♣r♦s tt π27(DT (GS ∪ T 3cp )) s tr♥t♦♥ ♥ S

♦♥ssts ♦ ♦♥② ♦♥ ♣♦♥t S ♦♥t♥s ♠♦r ♣♦♥ts t♥ t ♠♣t② s ♥ ♦♥② s♠r ♥ ♠♦r ♦s ②s ♦ ♥t t♦

♦ ♦♠tr rtr♦♥ t♦ tr π(DT (GS)) s s♠♣ ♦♠♣①♥ ts tr♥t♦♥ ♦ T

3c

rtr♦♥ t ♠tr ♦ t r♠sr♥ ♦ ♥② ttrr♦♥ ♥ DT (GS)s s♠r t♥ 1

2 c t♥ π(DT (GT )) s s♠♣ ♦♠♣① ♦r ♥② ♥t T ⊂ Dc tS ⊆ T

Pr♦♦ s ♦ ttrr♦♥ r ♦♠♣t② ♦♥t♥ ♥ ts r♠sr♥ ♥r ts ♦♥ ② t s ♠tr t ♠tr ♦ ♥② r♠sr♥ ss♠r t♥ 1

2 c t♥ s ♥ t tr♥t♦♥ r s♦rtr t♥ 12 c ♥ ♦rr t♦ rt

② ♦ ♥t t♦ t s♠ ♦ t ♥ts ♦ t t♦ s ♥s t♦ t st c s♥♦t ♣♦ss ♦t s r s♦rtr t♥ 1

2 c r♦♠ srt♦♥ ♥ ♦r♠ t ♦♦s tt π(DT (GS)) s s♠♣ ♦♠♣① ♠♦r ♣♦♥ts t ♠tr ♦t rst ♠♣t② ♥♥♦t ♦♠ rr ♠ ♦♦s

❲ ♥♦ ♣r♦ t ♦♠tr rtr♦♥ tt s s ♥ ♣rt

rtr♦♥ t st♦♥ ♦ DT (GS) ♦♥t♥s ♦♥② s s♦rtr t♥ 1√6c r

c s t ♥t ♦ Dc t♥ π(DT (T c)) s s♠♣ ♦♠♣① ♦r ♥② ♥t T ⊂ Dc

t S ⊆ T s♦ t s tr♥t♦♥ ♦ T3c

Pr♦♦ ss♠ tt tr s B ♦ ♠tr d tt ♦s ♥♦t ♦♥t♥ ♥② ♣♦♥t ♦ GS♥ ts ♥tr♦r ♦♥sr t ttrr♦♥ ∆ ♥ DT (GS) tt ♦♥t♥s t ♥tr ♦ B ♥t ♦ t rst ♦ ∆ s ♦♥ r♦♠ ♦ ② t ♥t ♦ t rrttrr♦♥ t r♠sr♥ B s 2d√

6 ♦ s ♥ DT (GS) r s♦rtr

t♥ 1√6c t♥ t ♠tr ♦ ♥② ♠♣t② s s♠r t♥ 1

2 c ♠ ♦♦s r♦♠rtr♦♥ ♥ ♠♠

♦t tt rtr ♥ r ♦♥② s♥t r rtr♦♥ s rt♥ rtr♦♥ r r ♣♦♥t sts t ♠①♠♠ ♠♣t② ♠tr s♦rtr t♥12 c t s ♦♥r t♥ 1√

6c ♠♦r t sss♦♥ ♦♥ t t♦ rtr ♥ ♦♥

♥ t♦♥ ♠♠ ♥ rtr♦♥ ♣r♦

Page 44: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♦rt♠

♦r♠ ♦rt♠ s ♦rrt t ②s ♦♠♣ts ♥② tr♥t♦♥ ♦♠♦♠♦r♣ t♦ T

3c

r rs♦♥ ♦ ♠♠ s ♥ t ♥①t st♦♥ ♦♦s♠♠t② r♦♠ rtr♦♥

♦r♦r② t S ⊂ Dc S 6= ∅ ♥ T ⊂ D4c ♥t ♣♦♥t sts Dc s t♥ π64(DT (GS ∪ T 4c)) s tr♥t♦♥ ♦ T

34c

Pr♦♦ rst ♠♣t② ♥ GS s ♠tr√

3 c ♦♠♥ D4c s ♦ ♥t 4c s ♠♦r t♥ t

√3 c s rtr♦♥ ♣♣s

♦t tt ♥ ♠♠ ♦r♦r② ♦s ♥♦t rqr T t♦ sst ♦ ♣♦♥t r ϕc(p ×Z

3) ♦r s♦♠ ♣♦♥t p ∈ Dc ♥ t♦ ts rst s r ♥ tt t②s rr ♥♠r ♦ ♣r♦ ♦♣s t♦ ♦♥sr t s ♠ sr t♦ ♣r♦ ♥ ts t♥r③s s② t♦ ♦tr stt♥s s s♥ ♦ ♦r sr ♥ ♣♣r♦tt ♦s ♦♠♣t♥ ♥ T

33c

♠♠② ♣♦♥ts ♥ ♦rr t♦ ♦ ♦♠♣t♥ ♥ T33c

t t ♥♥♥ t ♦rt♠strts t ♥ ♥t tr♥t♦♥ ♦ ♠♠② ♣♦♥t st P ♦s♥ s tt ♥② s♣rst♦ P s tr♥t♦♥ ♥ T

3c ♣♦ss ♠♠② ♣♦♥t st ♦ ♣♦♥ts s ♥ s

♦♦s

P :=c · (x, y, z) | x, y ∈

0, 1

3 , 23

, z ∈

0, 1

2

∪c ·

(16 + x, 1

6 + y, 14 + z

)| x, y ∈

0, 1

3 , 23

, z ∈

0, 1

2

r ♦r ♥ strt♦♥ ♦ t ♣r♦ ♥② tr♥t♦♥ ♦ t ♠♠②♣♦♥t st

r tr♥t♦♥ ♦ t ♠♠② ♣♦♥t st

♠tr ♦ t rst ♠♣t② ♥ t st P s s♠r t♥ 12c s rqr ②

rtr♦♥ ♣♦♥t st P s s② t♦ sr ♥ s♥t② s♠ ♦r ♣rt st ♦ ♥trst♥ t♦ ♥stt rtr t♦ ♥ t s♠st ♣♦ss ♣♦♥t st ♥ t♦♠♥s♦♥s t s ♥♦♥ tt t s♠st tr♥t♦♥ ♦ t♦rs s rts ❬ö❪♦r t tr♠♥s♦♥ t♦rs tr♥t♦♥ ♦ rts s ♥♦♥ ❬❪ t t s ♥♦t♥♦♥ tr ts s t s♠st ♣♦ss ♥♠r ♦ rts ♦r ♦t ss t s♠st♣♦♥t sts ♥♥ ♥② tr♥t♦♥ t t ♠tr ♦ t rst r♠sr♥ ♦♥ ② 1

2c r ♥♥♦♥

Page 45: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

Pr♦ tr♥t♦♥s

♥ t ♥♣t ♣♦♥ts ♥ S r ♥srt ♥t♦ t ♥t tr♥t♦♥ ♥ ② Pt ♣♦♥ts ♦ P r r♠♦ r♦♠ t tr♥t♦♥ ② ♦♥strt♦♥ t ♣♦♥t st S ∪ P♥s ♥② tr♥t♦♥ ♦ T

3c t ♥♣t ♣♦♥t st t♦t P ♦s ♥♦t ♥

tr♥t♦♥ ♦ T3c ♥②♠♦r t♥ t tr♥t♦♥ ♦♥rt t♦ T

33c

r♥ tr♠♦ ♦ ♦♥ ♦ t ♠♠② ♣♦♥ts

♦♥② ♦r ♦ ts ♣♣r♦ s t r♠♦ ♦ t ♣♦♥ts ♥ P r s t♦♥② t ♣♦t♥t ♦♥rs♦♥ t♦ T

33c

t t♦t s♥ t ♠♠② ♣♦♥t st t ♦tr♥t♦♥ ♦ ♦♠♣t ♥ T

33c

♥ ts s s ② t♦ ♥ ♠♦r ①♣♥s t ♥♣t ♣♦♥t st s r ♥♦ t♥ t ♦r ♦ r♠♦♥ ♣♦♥tss ♥ s t ♦♠♣t② ♦s ♦♠♣t♥ ♥ T

33c t s str t♥ t st♥r

♣♣r♦

♦♥ ♦♠♥

♦ sss♦♥ st r♠♥s t ♦r♥ ♦♠♥ Dc s ♥r ♦ c = (cx, cy, cz) ♥② t ♦♥st♥ts t ♥♠r ♦ sts ♦ t ♦r♥ s♣ t♦ strtt ♥ t ♥t trs♦ ♥ t♦ ♣t

t Th∗c t h = (hx, hy, hz) ♦r♥ s♣ ♦ T3c t ♣r♦t♦♥ ♠♣ πh∗c ♥

♦r♥ ♦♠♥ Dh∗c❲ rst rtr♦♥ t♦ ♥ t♦ st t♦ T

3c ♥ ♦rt♠ ♥ t

s ♦ ♥♦♥ ♦♠♥

rtr♦♥ t ♠tr ♦ t r♠sr♥ ♦ ♥② ttrr♦♥ ♥ DT (GS)s s♠r t♥ 1

2 cmin r cmin = mincx, cy, cz t♥ π(DT (GT )) s s♠♣ ♦♠♣① ♦r ♥② ♥t T ⊂ Dc t S ⊆ T

Pr♦♦ ♣r♦♦ ♦ ts rtr♦♥ s ss♥t② t s♠ s ♦r rtr♦♥ t♠tr ♦ ♥② r♠sr♥ s s♠r t♥ 1

2 cmin t♥ s ♥ DT (GS) rs♦rtr t♥ 1

2 cmin s♦rtst ♣♦ss ♥♦♥tr ② ♥ T3c s ♥t cmin ts

t♦ s t st♦♥ ♦ DT (GS) ♥♥♦t ♦r♠ s ② ♠ ♦♦s r♦♠♦r♠

❯s♥ rtr♦♥ ♥ t ♦r♥ s♣ rqr ♥ ♦rt♠

♠♠ t S ⊂ Dc S 6= ∅ ♥ T ⊂ Dh∗c ♥t ♣♦♥t sts t hi :=⌈2‖c‖

ci

♦r i = x, y, z ♥ πh∗c(DT (GS ∪ T h∗cp )) t T h∗c := ϕh∗c(T × Z

3) s tr♥t♦♥♦ T

3h∗c

Pr♦♦ rst ♠♣t② ♥ GS s ♠tr s♠r t♥ ‖c‖ ♦♠♥ Dh∗cs ♦ ♦ ♥ts hici ♦r i = x, y, z ♦♥t♦♥ hi =

⌈2‖c‖

ci

⌉♠♣s tt

hici ≥ 2‖c‖ ♣♣②♥ rtr♦♥ t♦ t t t♦rs t ♦r♥ ♦♠♥ Dh∗c ♣r♦st ♠

❲t ♥② tr♥t♦♥

t ♥② tr♥t♦♥ ♦r rr tr♥t♦♥ ♥r③s t ♥②tr♥t♦♥ ♥ t sts r s♣rs s♦ t ♣♦♥ts ❲ s♦rt♥tr♦t♦♥ ♦♥ t ♥② tr♥t♦♥s ♥ t♦♥

Page 46: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♦rt♠

t ♥② tr♥t♦♥ t t ♥② tr♥t♦♥ ♥ ♥♥q② ♥ ♥ ♥rt ss ❬❪ r s♦ tt t ♦ sss♦♥ ♥t♦♥ ♦rs ♥ t s♠ ② ♦r t ♥② tr♥t♦♥s ❲ s♦ ♣r♦ ♦♠tr rtr♦♥ s♥ t ♥t s♠r t♦ rtr♦♥ ♦s s t♦♥r③ ♦rt♠ t♦ ♦♠♣t ♣r♦ t ♥② tr♥t♦♥ s

t S st ♦ t ♣♦♥ts ♥ E3 ♣rs (p, wp) ∈ E

3 × R t Dc ♦ ♥t c ♥ S st ♦ t ♣♦♥ts ♥ Dc t W ♥ w rs♣t②♥♦t t rst ♥ s♠st t ♥ S t ❲(GS) ♥♦t t t ♥②tr♥t♦♥ ♦ E

3 ♥ ② GS

rtr♦♥ t ♦♥st ♦ ❲(GS) s s♦rtr t♥√

16 c2 − 8

3(W − w)

t♥ π(❲(T c)) s tr♥t♦♥ ♦ T3c ♦r ♥② ♥t T ⊂ Dc t S ⊆ T

♦t tt W = w ts ♦♥ rs t♦ 1√6c s t ♥t trs♦ ♦r

♥② tr♥t♦♥s ♣r♦♦ ♦ ts rst ss t ♦♦♥ ①r② ♠♠

♠♠ ♦♥sr ❲(GS) t ♦rt♦♦♥ t ♣♦♥t ♦ ttrr♦♥s t wo t♥ t ♥t ♦ t ♦♥st ♦ t ttrr♦♥ s ♥♦t rr t♥2√

wo + W − w

Pr♦♦ t (o, wo) ♥ ♦rt♦♦♥ t ♣♦♥t ♥ (p, wp), (q, wq) t♦ ♦ tt ♣♦♥ts ♦rt♦♦♥ t♦ (o, wo) ♥ st(o, p) =

√wp + wo ♥t

st(p, q) tt♥s ts ♠①♠♠ t s♠♥t [p, q] ♦♥t♥s o ♥ st(p, q) =√

wo + wp+√wo + wq s ①♣rss♦♥ s ♠①♠③ t t s ♠①♠③ ❲ ♥♦ tt ♥

♥ t ts ♦ ♣♦♥ts ♥ t tr♥t♦♥ ② t s♠ ♠♦♥t ♦s ♥♦t ♥ ttr♥t♦♥ ♦ ♥ ss♠ W − w t♦ t ♠①♠♠ ♣♦ss t ♠♦♦s r ♦r ♥ strt♦♥ ♥

o√

wp

q

p

√wo

√wo

√wq

r strt♦♥ ♦♥st ♣♦ss ♦ ttrr♦♥ t ♦rt♦♦♥s♣r ♦ rs

√wo

Pr♦♦ ♦ rtr♦♥ t λ t ♥t ♦ t ♦♥st ♥ ❲(GS) ♥

t r♠rs ♦ ♥② ttrr♦♥ ♥ ❲(GS) ♥♥♦t rr t♥√

38λ r♦♠

♠♠ ♦♦s tt t ♦♥st ♣♦ss ♦ ttrr♦♥ s ♦♥ ② λmax :=

2

√(√38λ

)2

+ W − w ♥♦ ♦♦s λ t♦ s♠r t♥√

16 c2 − 8

3(W − w) t♥

λmax s s♠r t♥ 12 c s ♥♦ ② ♦ ♥t t♦ ♥ ♦r ♥ π(❲(GS)) s

tr♥t♦♥ ♦r♥ t♦ ♦r♠ t♦tr t t q♥t ♦ srt♦♥

Page 47: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

Pr♦ tr♥t♦♥s

♦r t ♥② tr♥t♦♥s ♥ rtr ♣♦♥ts ♥♥♦t ♥rs t s③ ♦t rst r♠sr♥ ♥ s♦ π(❲(T c)) s tr♥t♦♥ s

♦r♦r② t η ♥ s η :=⌈8·(3 + 4

c (W − w))3/2⌉♥ h := η3 t Tp

sst ♦ t h ♦♣s ♦ p ♥ Dηc ♥ T ηcp := ϕηc(Tp × Z

3) ♥ πh(❲(GS ∪ T ηcp ))

s tr♥t♦♥ ♦ T 3ηc

Pr♦♦ S ♦♥ssts ♦ ♦♥② ♦♥ ♣♦♥t t♥ t t ♥② tr♥t♦♥ ♥② GS t② s ♥② tr♥t♦♥ s ♣r♦ ♦♣s ♦ t ♣♦♥t t s♠ t ♦ t rst ♦rt♦♦♥ s♣r ♦♥s t t rst r♠s♣r♥ s rs

√3

2 c ❲t t s♠ r♠♥t s ♥ t ♣r♦♦ ♦ rtr♦♥ t♠tr ♦ t rst ♦rt♦♦♥ s♣r tr ♥ ♥② ♦tr ♣♦♥t s ♦♥ ②

2·√

(√

32 c)2 + W − w ♦ ♠ sr tt ts ①♣rss♦♥ s s♠r t♥ 2·η ·c ♦♦s

η = ⌈8·(3 + 4c (W − w))3/2⌉

♥②ss

♦♠♣①t② ♥②ss

♥ ts t♦♥ s♦ tt s♥ t ♥② rr② t r♥♦♠③ ♦rsts♦♠♣①t② ♦ ♦rt♠ s s②♠♣t♦t② q t♦ t ♦♥ ♦ t ♦rt♠ ♦r♦♠♣t♥ t ♥② tr♥t♦♥ ♦ E

3t s rst sss t ♦♦♥ t♦ ♣♦♥ts ♦r ♦♥sr t ♥② rr②

♥ ♠♦r t ♦ t♦ tst ♦r t ♥t ♦ t ♦♥st ♥ ♦ t♦ ♦♥rtr♦♠ t tr♥t♦♥ ♦ T

3h∗c t♦ t tr♥t♦♥ ♦ T

3c

❲ ♠♥t♥ ♥ ♥s♦rt t strtr E tt rr♥s s tt r ♦♥rt♥ t trs♦ 1√

6cmin s s♦♦♥ s E s ♠♣t② ♥♦ tt t ♦♥st s s♠r

t♥ t trs♦ t♦t ♥♠r ♦ s tt r ♥srt t♦ ♥ r♠♦ r♦♠ Es t ♠♦st ♣r♦♣♦rt♦♥ t♦ t t♦t ♥♠r ♦ s♠♣s tt r rt ♥ str♦②r♥ t ♦rt♠ ❲ ♥ rt ss r♦♠ t s♠♣s t♦ tr s ♥ E ♥ t ♠♥t♥♥ ♦ E ♦s ♥♦t ♥ t ♦rt♠ ♦♠♣①t②

♦ ♦♥rt t tr♥t♦♥ ♦ T3h∗c t♦ DTT(S) ♥ ♦♥rt t♦ T

3c ♥

t♦ trt ♦r s ♥ rts t♦ t ♣r♦ ♦♣s ♣♥ ♦♥② ♦♥rtr♠♦r ♥ t♦ ♣t t ♥♥ rt♦♥s ♦ t♦s ttrr ♦s ♥♦rs ♥ t s s ♥r ♥ t s③ ♦ t tr♥t♦♥ ♥ ts ♦♠♥t ②t ♠♥ ♦♦♣

♥② rr② ♦r ♦rt♠ s ♥r♠♥t ♥ ♥ ♦♠♥t t ♥② rr② ❬❪ s s♦ t♦♥ ♥ ♥ts t strtrs s♥ ♦r ♥t ♦♠♣tt♦♥ ♦ ♥② tr♥t♦♥ ♦ E

d t s t ♥r♠♥t② ♥ s sr s t ♥tr♠t s st♦r t ♥② tr♥t♦♥s♦ ♥ ♥rs♥ sq♥ ♦ ssts ♦ t st ♦ ♥♣t ♣♦♥ts t st st♦rst ♦♠♣t tr♥t♦♥ r r ♣♦♥trs t♥ s♦♠ rts ♥ r♥t s♦rrs♣♦♥♥ t♦ t s♠ ♥♣t ♣♦♥t strtr ♦s ♦r st ♣♦♥t ♦t♦♥ ♥t ♦♠♣t tr♥t♦♥ ❲ rr t rr t♦ t ♦r♥ ♣♣r ♦r ♠♦r ♦♠♣tsr♣t♦♥ ♦ ts t strtr

Page 48: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥②ss

s strtr ♥ ♣t t♦ ♦r ♦rt♠ t T3h∗c t ♦r♥ s♣ ♦s♥

s ♣rs♥t t t ♥♥♥ ♦ t♦♥ ♥ ♦ t rr② st♦rs tr♥t♦♥ ♦ T

3h∗c ♥ t s rt ♥ ts tr♥t♦♥ s ♦♥rt ♥ ♣♦ss

t♦ tr♥t♦♥ ♦ T3c ♦t tt ♥ l st♦rs tr♥t♦♥ ♦ T

3c t♥

t ♥①t l + 1 s s♦ ♥ T3c s♥ t ♦♥t♥s ♠♦r ♣♦♥ts ♥ ts s♦ st♦rs

tr♥t♦♥ ♦ T3c ② rtr♦♥ ♦r s♦♠ l ♥ st♦r tr♥t♦♥

♦ T3h∗c t ♥①t l + 1 s ♦♥rt ♥t♦ T

3c ♥ ts s ♦r t rts

♦rrs♣♦♥♥ t♦ ♣r♦ ♦♣s ♦ ♥ ♥♣t ♣♦♥t ♥ tt l tr ♣♦♥tr t♦ t l + 1 st t♦ t s♠ rt① ♦rrs♣♦♥♥ t♦ ts ♥♦♥♣t ♣♦♥t ♥T

3c

r♥♦♠③ ♥②ss ♦ ❬❪ ss♠s t ♥srt♦♥ ♦ ♣♦♥ts ♦ S t♦ ♣r♦r♠♥ r♥♦♠ ♦rr ♥s t♦ ts ♥②ss ♥ ♦♠♣t♥ ♥ T

3h∗c r ♠♥♦r

♣♦♥ts r ♥srt ♥ sts ♦ ♦♥st♥t s③ t ♥♠r ♦ ♣r♦ ♦♣s ♥ ts stsr ♥srt ♥ r♥♦♠ ♦rr rst r♠♥s t s♠

♦r♠ ♦rt♠ s ♦♣t♠ r♥♦♠③ ♦rsts t♠ ♥ s♣ ♦♠♣①t② O(n2)

Pr♦♦ t S t ♥♣t ♣♦♥t st rt① st ♦ t ♥② tr♥t♦♥ ♥ i s ♥♦t ② Si ♥ t s ♦ t rr② r ♥♠r r♦♠ ♦tt♦♠ t♦ t♦♣ tts S0 = S t 1/α ♥♦t t ♣r♦t② tt ♣♦♥t s ♥ Si+1 ♥ tt t s ♥ Si♥ ♦rt♠ t ♣♦♥ts ♦ S ♥ ♥srt ♥ r♥♦♠ ♦rr t ♥ ♦♠♣t♥♥ T

33c ♦♣s ♦ ♣♦♥t r ♥srt ♦♥st② t S ′

i t st ♦♥t♥♥ ♦♣s ♦ ♣♦♥t ♦ Si

r♥♦♠③ ♦rsts ♥②ss ♥ ❬❪ s♦s tt t ①♣t ♦st ♦ t ♥ i s ♥r ♥ t rt① r ♥ α ♥ O(αn) t ♥♣t ♣♦♥ts r♥srt ♥ r♥♦♠ ♦rr ♣r♦♦ s s ♦♥ t t tt t ♥♠r ♦ ♣♦♥ts ♥Si tt r ♦sr t♦ qr② ♣♦♥t q t♥ t♦ ♥② ♦tr ♣♦♥t ♥ Si+1 s ♥ O(α) s♣r♦♣rt② ①t♥s t♦ t s ♦ ♦♠♣t♥ ♥ st ♦r♥ s♣ rt① st ♦t ♥② tr♥t♦♥ ♥ i s S ′

i s ♦r ♣♦♥t ♦ Si tr r ♦♣s ♥S ′

i t ♦ ♦♥ ♥ t ♠♦st t♠s r s st ♥ O(α) s t ♦st♦ t ♥ i s st ♥ O(αn) ♥ s♠♠♥ ♣ ♦r s ②s ♥ ①♣tO(n) ♦♠♣①t② ♦r ♦♥ ♣♦♥t ♥srt♦♥

♥ t ♥♥♥ ♦ ts st♦♥ s♦ tt t ♠♥t♥♥ ♦ t strtr E♦♥② rqrs t♦t ♥♠r ♦ O(n2) s t♦ ♥srt ♥ r♠♦ rtr♠♦r s♦ tt t ♦♥rs♦♥ r♦♠ T

33c

t♦ T3c s O(n2) t♦♦ ♥ t s ♣♣ ♦♥② ♦♥

r♥ t ♦rt♠ r♥

s♦ t ♠①♠♠ s③ ♦ t strtr E s ♥ O(n2) ❲ ♥srt t ♠♦st 27n ♣♦♥ts♥t♦ t ♥② tr♥t♦♥ s♦ t s②♠♣t♦t s③ ♦ t rr② ♦s ♥♦t ♥t rs♣t t♦ ❬❪

n ♥ t ♦♥ ♦r t ♣♦♥t ♥srt♦♥ ♦♠s r♦♠ t ♦rsts rt① r ♥t tr♥t♦♥ s ♦r tr♥t♦♥s t ♠①♠♠ rt① r s♠r t♥ O(n)t rsts ♥ st ♠♣r♦ s ♦♠♣①t② rst s♦ ♦s ♦r t ①t♥s♦♥s t♦♥♦♥ ♦♠♥s t♦♥ ♥ t♦ t ♥② tr♥t♦♥s t♦♥

Page 49: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

Pr♦ tr♥t♦♥s

♠r ♦ sts

♥ ts st♦♥ ♥ st♠t♦♥ ♦ t ♥♠r ♦ ♣♦♥ts rqr t♦ st t♦st ♦r♥ s♣ t ♥♣t ♣♦♥t st s ♥♦r♠② strt

❲ rst ♥ t ♥♦tt♦♥s s ♥ t ♦♦♥ sss♦♥ t E ♥ ♥t ♥X r♥♦♠ r ♦r E ❲ ♥♦t t ♣r♦t② ♦ E ② p(E) ♥ t ①♣t ♥ t r♥ ♦ X ② E[X] ♥ V [X] rs♣t② ❲♥ tr s ♥♦ ♠t②♦r t r♥♦♠ r s♦ s µ = E[X] ♥ σ =

√V [X] t♦ ♥♦t t ①♣t

♥ t st♥r t♦♥ rs♣t②❲ ♥t t♦ ♣rt t ♥♠r ♦ ♣♦♥ts rqr ♥ ♦rr t♦ rtr

♥ ♦r ♣rs② ♥ st ♦ ♣♦♥ts ♥♦r♠② strt ♥ t ♥t t s t ①♣t ♦r t ♥♠r ♦ ♣♦♥ts s tt t rst ♠♣t② s♠tr s s♠r t♥ 1

2 s ♣r♦♠ ♥ ♠♦ s P♦ss♦♥ ♣r♦ss ❬ ♥❪ ♦♥sr ♥ ♥♥t

r♥♦♠ ♣♦♥t st Π ♥ ② ♥t♥t♥st② P♦ss♦♥ ♣r♦ss ♦♥ E3 ♥ t C :=

[0, 3√

n]3 P♦ss♦♥ strt♦♥ s t ♦♦♥ ♣r♦♣rts t A ♥♦t sst ♦ E

3 ♦♦♠ ‖A‖ ♣r♦t② tt A ♦♥t♥s ①t② k ♣♦♥ts ♦ Π s ♥ ② p(|A ∩Π| = k) = e−‖A‖ ‖A‖k

k! ♥ t ♣r♦t② tt A ♦s ♥♦t ♦♥t♥ ♥② ♣♦♥t ♦ Π sp(|A ∩ Π| = 0) = e−‖A‖

①♣t ♥♠r ♦ ♣♦♥ts ♥ ♦♠ ♦ ♠sr ‖A‖ s t♥ ♥ s

E[|A ∩ Π|] =

∞∑

k=0

k · p(|A ∩ Π| = k) =

∞∑

k=0

k · e−‖A‖ ‖A‖k

k!= ‖A‖

② t ♣r♦♣rts ♦ t P♦ss♦♥ strt♦♥ ♥ r♦♠ t ♦♥strt♦♥ ♦ C ♦♦stt ①♣t ♥♠r ♦ ♣♦♥ts ♥ C s n t ΠC ♥♦t t st ♦ ♣♦♥ts ♦ Π tt ♥s C ΠC := Π ∩ C ❲ ♥♦t t ♥♠r ♦ ♣♦♥ts ♥ ΠC ② nC

t GC ♥♦t t r♦♣ ♦ tr ♦rt♦♦♥ ①s♥ tr♥st♦♥s t ♥♠♥t♦♠♥ C ♥ DT (GCΠC) s t ♥♥t ♣r♦ ♥② tr♥t♦♥ ♥ ② ΠC

♥ DT (GCΠC) ∩ C t st ♦ ttrr ♦ DT (Π) tt r ♦♠♣t② ♦♥t♥ ♥sC t♦tr t tr s ♥ t ♦♦♥ ♦♥sr DT (GCΠC) ∩ C ts s ♠♥s s♠♣♥ ♦t tt ♦♥sr t ♣♦♥t st GCΠC ♥st ♦ Π ♦ ♥♦t♥ t st ♦ ♣♦♥ts ♥s C ♦ t ♣♦♥t st GCΠC ∩ C st ♦♦s t P♦ss♦♥strt♦♥ ♣r♦♣rt② tt s ② s ♥ t ssq♥t sss♦♥

♥ s♠r ② s ♦♥ ② ❬❨❪ ♥ s♦ t ♦♦♥ t♦r♠

♦r♠ t C ♥ ΠC ♥ s ♦ t µO ♥♦t t ①♣t ♦ t♦♠ ♦ t rst ♠♣t② ♥ t ♥♥t ♣r♦ ♥② tr♥t♦♥ DT (GCΠC)♥ t ♦♦♥ ♦s

0.5 lnn

n≤ µO ≤ 5 lnn + 2

n.

Pr♦♦ ❲ ♥♦t ② Bx ♦ ♦♠ x Bx s s t♦ ♠♣t② Bx ∩ Π = ∅ ♣r♦t② tt B5 ln n s ♠♣t② s ♥ ② p(B5 ln n ♠♣t②) = e−5 ln n = 1

n5 ♥p(Bx ♠♣t②) ≤ 1

n5 ♦r x ≥ 5 lnn ❲ ♦♠♣t t ♣r♦t② ♦ t ①st♥ ♦ ♥♠♣t② r♠sr♥ ♦ ♦♠ t st 5 lnn ♥ DT (Π)∩C r♠sr♥ ♥DT (Π) s ♥ ② ♣♦♥ts ts tr r

(nC

4

)♣♦ssts t♦ ♥ ttrr♦♥ t

♣♦♥ts ♥ Π ∩ C s rts ❲ ♥ ♣♣r ♦♥ ♦r t ♣r♦t② tt(nC

4

)≥ n4

Page 50: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥②ss

t X t r♥♦♠ r tt srs t ♥♠r ♦ ♣♦♥ts r♦♠ Π tt ♥ Cr♦♠ t t tt X s P♦ss♦♥ strt♦♥ ♥♦ tt µ = n ♥ σ =

√n ❲

♥♦ ♣♣② t ♥t ♥qt② P (X − µ ≥ k) ≤ σ2

σ2+k2 ♦♦s♥ k = n ts ②s

P (X − n ≥ n) ≤ 1n+1 ♠♣s tt t ♣r♦t② ♦r nC ≥ 2n s t ♠♦st 1

n+1

nC = 2n t♥ tr r(2n4

)< n4 ♣♦ssts t♦ ♦♦s r♦♠ t BC ♥♦t t st ♦

r♠sr♥ s ♥ ② ♣♦ss t♣s ♦ ♣♦♥ts ♥ Π ∩ C ♣r♦t②tt ♦♥ ♦ t s ♥ BC s ♦♠ rr t♥ 5 lnn ♥ s ♠♣t② ♥ nC ≤ 2n st♥ p(∃ ♠♣t② B5 ln n ∈ BC | nC ≤ 2n) ≤

(2n4

)· 1

n5 < 1n+1

♦ ♥② t ♦♦♥ ♣r♦ts

p(∃ ♠♣t② B5 ln n ∈ BC | nC ≤ 2n) ≤ 1

np(nC ≤ 2n) ≤ 1

p(∃ ♠♣t② B5 ln n ∈ BC | nC ≥ 2n) ≤ 1 p(nC ≥ 2n) ≤ 1n

♠♠♥ ♣ t ♦♥t♦♥ ♣r♦ts s p(∃ ♠♣t② B5 ln n ∈ BC) ≤ 2n

t Y ♥♦t t r♥♦♠ r tt srs t ♠tr ♦ t rst ♠♣t②r♠sr♥ ♥ (Π)∩C ♥ r♦♠ t ♦ sss♦♥ t ♣r♦t②p(Y ≥ 5 lnn) ≤ 2

n ♦♠ ♦ t s ♦♥ r♦♠ ♦ ② t ♦♠ ♦ C s n ♦ ♥ ♥ ♣♣r ♦♥ ♦r t ①♣t ♦ Y t f(x) ♥♦tt ♣r♦t② ♥st② ♥t♦♥ ♦ t strt♦♥ ♦ Y ♥

E[Y ] =

∫ ∞

0xf(x)dx =

∫ 5 ln n

0xf(x)dx +

∫ n

5 ln nxf(x)dx +

∫ ∞

nxf(x)dx

≤ 5 lnn · p(Y ≤ 5 lnn) + n · p(Y ≥ 5 lnn) + 0 ≤ 5 lnn + 2

r♦♠ ❬❨❪ ♥♦ tt E[Y ] ≥ 0.5 lnn P♦ss♦♥ ♣r♦ss sr s♦ r s ♠♦ s tt t r♦t ♦ t

tt ♦♥t♥s t ♣♦♥ts ♦ t tr♥t♦♥ s t ♥♠r ♦ ♣♦♥ts ♥ t ❲♥♦♥sr♥ ♣r♦ tr♥t♦♥s ♥t t♦ t s③ ♦ t ♦♥st♥t ♥ ♠♦ ② rs♥ Π s tt t C s rs t♦ [0, 1]3 ♦sss♦♥ r♠♥s s t ♥② tr♥t♦♥ s ♥r♥t t♦ rs♥

t Π′ ♥♦t t rs rs♦♥ ♦ t ♣♦♥t st Π rstrt t♦ [0, 1]3 ♥ ♦♣♣r♦② ♦♥t♦ E

3 Π′ := 13√

n· p | p ∈ Π t Y ′ ♥♦t t r♥♦♠ r tt

♦rrs♣♦♥s t♦ Y t t rs♣t t♦ t rs rs♥ s t ♦♠♦ t ♠♣t② s ② n s♦ ts ♣r♦s t t♦r♠ ♦r µ = E[Y ′]

t ♥♦ Y ′d ♥♦t t r♥♦♠ r tt srs t ♠tr ♦ t rst ♠♣t②

♥ DT (Π′) ❲ t t ♦♥s ♦r ts ①♣t rt② r♦♠ t ♦♥s ♦♥ t♠♣t② ♦♠s ♥ ♦r♠

3

√3

π

lnn

n≤ E[Y ′

d] ≤ 3

√30 lnn + 12

π · n

♦ ♥ st♠t t ♥♠r ♦ ♥♦r♠② strt ♣♦♥ts rqr ♦r t ①♣t ♦ t rst ♠tr t♦ s♠r t♥ 1

2 rr♥♥ t t ♣rtqt♦♥ ②s 24 ≤ n rrr♥♥ t rt ♣rt s n ≤ 507 ♦ ♦r ♥♦r♠②strt r♥♦♠ ♣♦♥t st t ①♣t ♦ t s③ ♦ t rst ♠♣t② r♠sr♥ s s♠r t♥ 1

2 t ♣♦♥t st s ♠♦r t♥ ♣♦♥ts

t ♦♥s r♥t ♦ t ♥♦♥ ②s ♥qt②

Page 51: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

Pr♦ tr♥t♦♥s

♦t tt t ♦♥st ♥ ♥② tr♥t♦♥ s ♦♥ ② t ♠tr ♦t rst ♠♣t② s t s♠ ♥②ss ♦rs ♦r st♠t♥ t ♥♠r ♦ ♣♦♥tsrqr s tt t ♦♥st ♥ t tr♥t♦♥ s s♦rtr t♥ 1√

6s rqr ②

rtr♦♥ ♥ ts s t♦ r♣ t ♦♥st♥t ♦ 12 ♦r t ♠tr ②

1√6 r♦♠ qt♦♥ t♥ ♦♦s 56 ≤ n ♥ n ≤ 1030♥ t♦♥ ♣rs♥t ①♣r♠♥t rsts ♦♥ t ♥♠r ♦ ♣♦♥ts rqr ②

rtr ♥

Page 52: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣tr

♠♣♠♥tt♦♥

♥ ts ♣tr sr ♦r ♠♣♠♥tt♦♥ ♦ ♣r♦ tr♥t♦♥s ♥ ♠♣♠♥tt♦♥ s s ♦♥ t tr♥t♦♥s ♠♣♠♥tt♦♥ tt r② ①stt rst r ♥tr♦t♦♥ t♦ ♥ ♠♦r t ♦♦ ♦♥ t♠♣♠♥tt♦♥ ♦ t tr♥t♦♥s trrs ♣rs♥t t ♠♣♠♥tt♦♥ ♦t ♣r♦ tr♥t♦♥s ♥ ♠♦r t ♥②ss ♦ t ♦♠♣①t② ♦t ♠♥ ♥t♦♥s ♥ s♦ t ♣rt ♥② ♦ ♦r ♠♣♠♥tt♦♥ ♥ ①♣r♠♥ts ♦♥ ♦t ♥rt ♥ r♦r t ♥② ♦rt ♦♥ ①t♥s♦♥s tt ♠♣♠♥t t♦♥②

♥tr♦t♦♥ t♦

♦♠♣tt♦♥ ♦♠tr② ♦rt♠s rr② s ♦t♦♥ ♦ ♦♣♥ s♦r♠♣♠♥tt♦♥s ♦ ♦♠tr t strtrs ♥ ♦rt♠s ❬❪ ts s♥ ♦♦s t♥r ♣r♦r♠♠♥ ♣r♠ ❬s ❪ s ♥s t sr t♦ s② ♣ r♥t♦♠♣♦♥♥ts t♦tr

♥ ♥r ♣r♦r♠♠♥ ♦♥♣t srs t t②♣s ♥ ♦♣rt♦♥s tt ♠st ♠ ss s ♠♦ ♦ s♣ ♦♥♣t t ♠♣♠♥ts t rqr♦♣rt♦♥s ♥ t②♣s

♠♣♠♥tt♦♥s ♦ ♦♠tr ♦rt♠s ♥ strt② s♣rt t ♦♠♥t♦r♣rts ♦ t ♦rt♠s r♦♠ t ♦♠tr ♦♠♣tt♦♥s ♥ ts ② r♥t ♠♣♠♥tt♦♥s ♦ t ♦♠tr ♦♠♣tt♦♥s ♥ ♣ ♥t♦ ♥ ♦rt♠ ♠♣♠♥tt♦♥♦♠ s ♦♠tr ♥t♦♥t② s ② t ♥ t ♦♠tr② r♥ tt sr ♦

♥ ♠♦r ♣r♦♠ ♥ ♠♣♠♥t♥ ♦♠♣tt♦♥ ♦♠tr② ♦rt♠s s tt ♦♠♣trs ♦ ♥♦t s♣♦s ♦ r t ♣♦sst② t♦ ♣r♦r♠ ①t ♦♠♣tt♦♥s♦♥ r ♥♠rs ♦♥♦ rr♦rs ♥ ♦♠♣tt♦♥s ♥ t♦ ♥♥ ♦r ♥ t♠♣♠♥tt♦♥ ♦ ♦♠tr ♦rt♠s tt♥r t ❬P+❪ s♦♥ tt ts s♥♦t ♣r② t♦rt ♣r♦♠ ♥r② tr s tr♦ t♥ ♥② ♥ ①t♥ss ♥r ♣r♦r♠♠♥ ♣♣r♦ ♥s t sr t♦ ♦♦s st ♥♠rt②♣ ♥ ♣ t ♥t♦ t ♦♠tr② r♥

♠r t②♣s

♥ ♣r♥♣ t sr ♥ ♣r♦ s ♦♥ ♥♠r t②♣ t♦ ♣r♦r♠ t rt♠t ♦♣rt♦♥s

Page 53: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

rqr ② ♥ ♦rt♠ ♥ tr r sr ♥♠r t②♣s

• t♥ ♦t♥♣♦♥t ♥♠r t②♣ ♦ ♦ ♥♠r t②♣ sr② st t ♦s ♥♦t ♣r♦r♠ ①t ♦♠♣tt♦♥s t ♦♥♦r♠s t♦ t st♥r ❬♦ ❪

• t♣rs♦♥ ♦t♥♣♦♥t ♥♠r t②♣s ② r ♣rs♦♥ t♥♦ t t② r s♦r ♥ st ♥♦t t♦ ②s ♣r♦ ①t ♦♠♣tt♦♥s

• ♥tr rt♠t s ♥♠r t②♣ ♠♥t♥s t♦ ♥♠rs tt r ♥r② ♦ st ♥ ♥①t ♥♠r t②♣ s ♦r ♥ ♣♣r ♦♥ ♦ t ♥♠r t②t② s♦ r♣rs♥t

• t♦♥ ♥♠rs s ♥♠r t②♣ ♠♥t♥s t♦ ♥tr ♥♠rs ♥♠rt♦r♥ ♥♦♠♥t♦r s ♦♥ s t ♥♠rs t♦ r♣rs♥t r rt♦♥ ts ♥♠rt②♣s r ①t t t ①♣♥s ♦ s♦r ♣r♦r♠♥

• r ♥♠rs ♥♠r t②♣s ♥ r♣rs♥t r r♦♦ts ♦ ♣♦②♥♦♠st ♥tr ♦♥ts ❯♥♦rt♥t② ♦♠♣tt♦♥s ♦♥ r ♥♠rs r qt①♣♥s

♦♠tr② r♥s

♥ ♦♠tr ♦rt♠s tr r t♦ t②♣s ♦ ♦♠tr ♦♠♣tt♦♥s ♣rtt♦♥s ♥ ♦♠tr ♦♥strt♦♥s

♦♠tr ♣rts ♥ st ♦ ♦♠tr ♦ts ♥t t♦ ♥♦ tr ♦r♥♦t t② rt♥ ♣r♦♣rt② st ♦ ♣♦ss ♥srs ♦ ♦♠tr ♣rts s♠ ♥ srt ①♠♣ ♥ tr ♣♦♥ts ♥ E

2 tr t tr♣♦♥t s t♦ t t ♦r t♦ t rt ♦ t ♥ ♥ ② t rst t♦ ♣♦♥ts rr tr ♣♦ss ♥srs t rt ①t② ♦♥ t ♥

♦♠tr ♦♥strt♦♥ ♥ st ♦ ♦♠tr ♦ts ♦♠♣t ♥ ♦♠tr♦t ♦t ♦ t♠ ①♠♣ ♦♠♣t t ♥tr ♦ t r♠sr♥ r ♦tr ♣♦♥ts ♥ E

2

♦♠tr② r♥ ♠st ♣r♦ ♦t♦♥ ♦ ♦♥st♥t s③ ♦♠tr ♦ts♥ E

2 ♥ E3 ♥ ♦♠tr ♣rts ♥ ♦♥strt♦♥s ♦ ♦♥st♥t t♦♥ t♠

♥♦♥①st st ♦♥ssts ♦

• ♦♠tr ♦ts P♦♥t❴ P♦♥t❴ ♠♥t❴ ♠♥t❴

r♥❴ r♥❴ trr♦♥❴ r❴ ♣r❴

• Prts ♦♥r❴ ♦♥r❴ q❴ q❴

r♥tt♦♥❴ r♥tt♦♥❴

r♥tr❴ r♥t♣r❴

• ♦♥strt♦♥s ♦♠♣tr❴ ♦♠♣tr❴

♦♥strtr♠♥tr❴ ♦♥strtr♠♥tr❴

♦♠♣tqrst♥❴ ♦♠♣tqrst♥❴

Page 54: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

tr♥t♦♥s

♦t tt tr r ♦♠tr ♦♥strt♦♥s tt ♦ ♥♦t ♣r♦r♠ ♥② ♦♠♣tt♦♥s ♦♥strtr♥❴ s ♦♥strt♦♥s ♦ ♥♦t ♠♣♦s ♥② rqr♠♥ts ♦♥ t♥♠r t②♣s ♥ t ♦♦♥ ts t②♣ ♦ ♦♥strt♦♥s tr ♦♥strt♦♥s

r r r♥t ♣♣r♦s t♦ ♠♣r♦ t ♣r♦r♠♥ ♦ t r♥ ♥ ♣♣r♦t♦ rt t ♣rt t♦♥ s sr ② ❬❱❪ ♥ rst st♣ t ♣rts t s♥ st t ♣♣r♦①♠t ♥♠r t②♣ t ♥♦♥ rr♦r ♦♥ trst ♥ rt s♥ t rr♦r ♦♥ t ♣rt t♦♥ s ♦♥ trs trs♦rts t♦ s♦r t ①t ♥♠r t②♣ rstrt♥ t ♦♠♣tt♦♥ r♦♠ srt s♣♣r♦ s s ♦♥ t tt ♥ ♠♦st ss t s s♥t t♦ s ♥ ♣♣r♦①♠t♥♠r t②♣ t♦ t t ♣rt ♥② ♥ ss t ①t t♦♥ ♠st s ♦ t ♦r ♦ t♥ ♣rts t s ♦t ② t s♣♣r♦♠ s♥ ♥ ♣♣r♦①♠t ♥♠r t②♣ sr ♣♣r♦ s s♦ rt♠ttr♥ ♥ t tr r♥ ♣r♦s tr ♣rts ♦r t ♦♠tr② r♥❬P P❪ ♥♦tr ♣♣r♦ tt ♦♥♥trts ♦♥ ♦♠tr ♦♥strt♦♥s s ③② t♦♥ ❬P❪ ♥ ts s t rt♠t ①♣rss♦♥ tt s t♦ ts ♥♦t t ♠♠t② t ♦♥② ♥ rqr

♦t tt ①t t♦♥ ♦ ♣rts s sr t♥ ①t ♦♠♣tt♦♥ ♦ ♦♥strt♦♥s s♦ ♦r ♦rt♠s tt ♦ ♥♦t ♣r♦r♠ ♥② ♦♠tr ♦♥strt♦♥s ♥♠r t②♣♣r♦♥ ♦♥② ①t ♣rts ♥ s t♦ ♠♣r♦ t ♣r♦r♠♥

♦♠tr ♦rt♠s

♥ t ♣tr ♥ ♦rt♠ ♠♣♠♥t ♥ ♥s st ♦ ♦♠tr ♦ts♣rts ♥ ♦♥strt♦♥s t rqrs s r ♣r♦ tr♦ t♠♣t ♣r♠tr t s♦ ♦♠tr trts ss t♥ t r♥ ♥ sr s trts sst s♦♠t♠s s♣③ ♦ts ♣rts ♦r ♦♥strt♦♥s r ♥ s♦ s♣trts ss s rqr trts ss ts ts t ♥♠r t②♣ s t♠♣t r♠♥t sr ♥ r② ♦♦s t ♥♠r t②♣ t♦ s ♥ s ♥ ♥①♥ t ♣r♦ trts ss t sr ♦♥ ♠♣♠♥tt♦♥ ♦♥ t ts ♦st rs♣♦♥st② t♦ ♦♦s ♥ ♣♣r♦♣rt ♥♠r t②♣ ♣♥♥ ♦♥ tr ♦r♥♦t ♦♠tr ♦♥strt♦♥s r s ♥ t ♦rt♠ r ♦r s♠t ♦♥ t t♠♣t ♣r♠tr rr②

CGAL Algorithm

Geometric traits ...NT ...

r s ♦ t♠♣ts ♥ t②♣ ♦rt♠ ♥♠r t②♣

tr♥t♦♥s

s ♦r s s ♦♥ t tr♥t♦♥s ❬P❪ tt ♠♥② ♥ ♦♣ ② ②♥ P♦♥ ♥ ♦♥q t ♦♠♣ts sr t②♣s ♦ tr♥t♦♥s ♦♣♦♥t sts ♥ E

3 tr♥t♦♥s r st♦r ♥ t tr♥t♦♥ t strtr ❬P❪ ❲ r② ♥tr♦ t ♠♣♠♥tt♦♥ t strss ♦♥ t ♣rts tt rrqr ♥ t sss♦♥ ♦♥ t ♠♣♠♥tt♦♥ ♦ ♣r♦ tr♥t♦♥s tr ♦♥

Page 55: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

♣rt r♦♠ ♦♠♣t♥ tr♥t♦♥s ♦ E3 tr s s♦ ♥t♦♥t② ♦r ♦♠♣t♥

♥② tr♥t♦♥s ♥ rr tr♥t♦♥s ♦rt♠ s s ♥r♠♥t ♣♦♥ts r ♥srt ♦♥ ② ♦♥ ❲ ♥♦ r② r t s♦tr s♥

ss r♥t♦♥❴ ♠♣♠♥ts t ♥t♦♥t② t♦ ♦♠♣t ♥ ss tr♥t♦♥s ♦ ♠♥s♦♥ ≤ 3 t s t♠♣t ② t ♦♠tr trts ♥ t t strtrr r t♦ r sss ♥②❴r♥t♦♥❴ ♥ r❴tr♥t♦♥❴ s♦ r

Triangulation_3

GT:class

TDS:class

Delaunay_triangulation_3

GT:class

TDS:class

Regular_triangulation_3

GT:class

TDS:class

r s♥ ♦ t tr♥t♦♥s rrs t♦ t ♦♠tr trts ss♥ t♦ t tr♥t♦♥ t strtr

tr♥t♦♥ trts

♦ts ♣rts ♥ ♦♥strt♦♥s rqr ② t ♥② tr♥t♦♥ ♦♠♣tt♦♥ r ♦♥t♥ ♥ t r♥ s t s ♥♦t rqr t♦ ♣r♦ s♣♦♠tr trts ss ♦ ♦♠♣t ♥② tr♥t♦♥s

♦♠tr trts ♦r ♦♠♣t♥ tr♥t♦♥s ♠st ♦♥t♥

• ♦♠tr ♦ts P♦♥t❴ ♠♥t❴ r♥❴ trr♦♥❴

• ♦♠tr ♣rts ♦♠♣r❳❨❩❴ r♥tt♦♥❴ ♥ ♠♦r ♦r trt♥♥rt ♠♥s♦♥s

• ♦♠tr ♦♥strt♦♥s ♦♠♣tt♦♥ ♦ tr♥t♦♥s ♦♥② rqrs tr♦♥strt♦♥s t♦ ♦♥strt t ♦♠tr ♦ts

♦r ♥② tr♥t♦♥s t ♣rt r♥t♣r❴ s rqr t♦♥② t tsts ♦r ♦r ♥ ♣♦♥ts tt r ♥♦t ♦♣♥r tr t ♣♦♥t s ♥s♦ts ♦r ♦♥ t s♣r ♥ ② t rst ♦r ♣♦♥ts ♦r t ❱♦r♦♥♦ ♦t♣t t ♦♥strt♦♥ ♦♥strtr♠♥tr❴ s rqr t♦♥② ♥ ♥② ♦r rr tr♥t♦♥s t P♦rst❴ ♣rt s rqr ♥st ♦ t r♥t♣r❴tst ♦t tt ♦♥strtr♠♥tr❴ s t ♦♥② ♥♦♥tr ♦♥strt♦♥ ♥ t s♦♥② rqr ♦r t ♦♠♣tt♦♥ ♦ t ❱♦r♦♥♦ r♠ s ♦r ♦♠♣t♥ t ♥② tr♥t♦♥ t ss t♦ s ♥♠r t②♣ tt ♦♥② ♣r♦s ①t ♣rtt♦♥ ♥ ♥♦ ①t ♦♥strt♦♥s

tr♥t♦♥ t strtr

tr♥t♦♥ t strtr ♠♣♠♥ts t t strtr t♦ st♦r tr♥t♦♥s♦ ♠♥s♦♥ ≤ 3 ♦r♠② t st♦rs s♠♣ ♦♠♣① ♦♠♦♠♦r♣ t♦ tr♠♥s♦♥ ♦♠♣t s♣ t♦t ♦♥rs s E

3 s ♥♦t ♦♠♣t rt① t ♥♥t②v∞ s t♦ t ♣♦♥t st ♥ t st♦r ♦♠♣① s tr♥t♦♥ ♦ E

3 ∪ ∞ r

Page 56: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣r♦ tr♥t♦♥s

♦♥② sr t ♠♥s♦♥ s t s ♦ ♠♥s♦♥ tr s ttr♥t♦♥s ♦ T

3c tt ♥t t♦ st♦r ②s ♠♥s♦♥ tr

tr♥t♦♥ t strtr st♦rs tr♥t♦♥s ♥ t ♦♦♥ ② t st♦rst rts ♥ t s r rts ♦rrs♣♦♥ t♦ ♣♦♥ts ♥ t ♦♠tr ②r ♥s ♦rrs♣♦♥ t♦ ttrr rt① ♦♥t♥s ♣♦♥tr t♦ ♦♥ ♦ t s t s♥♥t t♦ t♦♥② t ♦♥t♥s t ♦♦r♥ts ♦ t ♣♦♥t t ♦rrs♣♦♥s t♦ s st♦r t ♦♦♥ ♥♦r♠t♦♥

• ♦r ♣♦♥trs t♦ rts ♥① r♦♠ 0 t♦ 3

• ♦r ♣♦♥trs t♦ ♥t s ♥① r♦♠ 0 t♦ 3 r ♥① i ♦rrs♣♦♥s t♦ t♥t ♦♣♣♦st ♦ rt① i

♦r ♠♥s♦♥ s♠♣s s ♥ ts r ♠♣t② r♣rs♥t s♦♦s ♥ ♥ ss tr♦ ♦♥ ♦ t s t s ♥♥t t♦ ♥t♥ tt♦ ♥s tt tr♠♥ t rts tt ♦♥ t♦ t t ♥ sstr♦ ♦♥ ♦ t t♦ s t s ♥♥t t♦ ♥t♥ t ♥① ♦ t rt① tt s♦♣♣♦st t♦ t t t ♦♥② rt① ♦ t tt ♦s ♥♦t ♦♥ t♦ t t r ♦r ♥ strt♦♥

vextex 0 vertex 1

vertex 2

vertex 3

facet 0

neighbor 0

edge (1, 3)

r ♣rs♥tt♦♥ ♦ tr♥t♦♥ ♥ t t strtr ❬P❪

ss r♣rs♥t♥ t tr♥t♦♥ t strtr s r♥t♦♥❴t❴strtr❴t s t♠♣t ② rt① ss ♥ ss t sss r ♣r♦ t ♥② ssstt ♠t t rqr♠♥ts ♥ ♥ t rs♣t ♦♥♣ts ♥ s r♦♠ t tstrtr t rts ♥ s r t②♣② ss s♥ ♥s ♥ ♥

srs ♦♥♣t tt r♣rs♥ts ♣♦♥trs t②♣s t♦ ss rts ♥ s ♥ ttr♥t♦♥ t strtr r ♥♠ ❱rt①❴♥ ♥ ❴♥

♣r♦ tr♥t♦♥s

♥ ts st♦♥ sr t ♠♣♠♥tt♦♥ ♦ t ♦rt♠ ♦r ♦♠♣t♥ t ♣r♦♥② tr♥t♦♥ ♦ ♣♦♥t st s sr ♥ ♣tr

❲ rst ♥♠♥ ♦♥♥t♦♥s ♦r t ♦♦♥ sss♦♥s ❲ s t ♥♦tt♦♥sT

3c ♥ T

33c

s ♥ ♥ ♣tr t ss♠ tt c r♣rs♥ts ♦ ♥t c♠♠r tt rts r♣rs♥t ♦rts ♦ t ♥♣t ♣♦♥ts ♥r t t♦♥ ♦ t r♦♣(Z3,+) ♦r (3Z

3,+) ♥ ♦♠♣t♥ ♥ T3c ♦r T

33c rs♣t② ❲♥ ♦♠♣t♥ ♥ T

33c

s t ♦♦♥ ♥♠♥ ♦♥♥t♦♥s ② ♥ ♦r♥ rt① ♠♥ rt① ♦sr♣rs♥tt ♥ D3c s ♥ Dc ② ♣r♦ ♦♣② ♠♥ rt① ♦s r♣rs♥tt♥ D3c ♦s ♥♦t ♥ Dc r ♦r ♥ strt♦♥

Page 57: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

r strt♦♥ ♥ ♦r♥ rt① t ts t ♣r♦ ♦♣s ♥ st♦r♥ s♣ ♦ T

2c

r♦♠ ♣tr ♥ t♦♥ ♥ t ♦♦♥ ♠♥ r♥s t♥E

3 ♥ T3c t rs♣t t♦ t ♠♣♠♥tt♦♥

• s ♦ ♦sts

• s ♦ ♦r♥ s♣s

• ♥♦ ♥ ♦r rt① t ♥♥t②

• ♥♦ ♥ ♦r trt♥ ♠♥s♦♥ t♦ ♥ s♠r

❲ ♥♦ t ♦r s♥ ♦ t ♠♣♠♥tt♦♥ ♥ ♣rs♥t ♥ ♠♦r t♦ t ♦sts r ♠♣♠♥t ♦ t ♦♠tr trts ss ♠st ♣t ♦ t♦r♥ s♣s r ♠♥ ♥ ♦ t r♥t st♣s ♦ t ♦rt♠ ♠st ♣ts s ♣♦♥t ♦t♦♥ ♣♦♥t ♥srt♦♥ ♥ rt① r♠♦ ♥② ♣rs♥t t♦♥♥t♦♥ts s s ss ♥t♦♥s s♣ t♦ T

3c ♣tt♦♥ ♦ t ♣♦♥t ♦t♦♥

strts ♥ ♥t♦♥s ♦r ❱♦r♦♥♦ ♦t♣t

s♥

♣r① Pr♦❴ t♦ ss ♥♠s tr♠♥s t t②♣ ♦ ♣r♦t② t tr♠♥stt ♦♠♣t ♥ s♣ ♦♠♦♠♦r♣ t♦ T

3c s ♦♣♣♦s t♦ ♦tr ♣♦ss ♣r♦

s♣s s s ♦rt s♣s ♦ E3 ♥r t t♦♥ ♦ r♦♣ s♣♥♥ ② t♦ ♦r ♦♥

tr♥st♦♥s ♦♥② s s♦ t♦♥ s♥ ♦ t ♣r♦ tr♥t♦♥s s r② s♠r t♦ t s♥ ♦ t

tr♥t♦♥s ss Pr♦❴❴tr♥t♦♥❴ ♦♥t♥s t ♥t♦♥t② tt s ♥♦t s♣ t♦ ♥② tr♥t♦♥s t s ♠♥② ss ♥t♦♥s ♥t ♣♦♥t ♦t♦♥ ♥t♦♥t② s♣③t♦♥ Pr♦❴❴♥②❴tr♥t♦♥❴♦♥t♥s t ♥② s♣ ♥ ❱♦r♦♥♦ s♣ ♥t♦♥t② t s ♣♦ss t♦ ♥♦tr ss Pr♦❴❴rr❴tr♥t♦♥❴ s s♣③t♦♥ ♦ Pr♦❴❴tr♥t♦♥❴ ♥ t s♠ ② s ♦r t rr tr♥t♦♥s ♥ E

3 s r ♥ t♦ tr s ♥♦ ♦♥♣t ♣r♦♠ t ss Pr♦❴❴rr❴tr♥t♦♥❴s ♥♦t ♥ ♠♣♠♥t

s ♥ t tr♥t♦♥s t ♣r♦ tr♥t♦♥ sss t♦ t♠♣t ♣r♠trs t ♦♠tr trts ♥ t tr♥t♦♥ t strtr rst♦♥ s sr ♥ t♦♥ ♦r t s♦♥ ♦♥ t ①st♥ ♠♣♠♥tt♦♥ ♦ ttr♥t♦♥ t strtr ♥ s s sr ♥ t♦♥ t tr♥t♦♥t strtr st♦rs s♠♣ ♦♠♣① t♦t ♦♥r② tr♥t♦♥ ♥ T

3c s

s♠♣ ♦♠♣① ♦♠♦♠♦r♣ t♦ T3c ♥ ts t♦t ♦♥r② ♦ ♥ rs t

Page 58: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣r♦ tr♥t♦♥s

Periodic_3_triangulation_3

GT:class

TDS:class

Periodic_3_Delaunay_triangulation_3

GT:class

TDS:class

Periodic_3_regular_triangulation_3

GT:class

TDS:class

r s♥ ♦ t ♣r♦ tr♥t♦♥s rrs t♦ t ♦♠trtrts ss ♥ t♦ t tr♥t♦♥ t strtr

ss r♥t♦♥❴t❴strtr❴ rt② ♥② t rt① ss ♥ t ss♥ t♦ ♥ s sr ♥ t♦♥

sts

s sr ♥ t♦♥ s♠♣s r r♣rs♥t ② ♣♦♥t♦st ♣rs r t♣♦♥ts ♥ t ♦r♥ ♦♠♥ ♥ t ♦sts r ♠♥ts ♦ Z

3 ♠♠r tt ♣♦♥t p t♦tr t ♥ ♦st o ♦rrs♣♦♥s t♦ t ♣♦♥t ϕc(p, o) = p + c ∗ o ♥ E

3 ϕc(p, o) | o ∈ Z

3 srs t ♦rt ♦ p ♥r t t♦♥ ♦ t r♦♣ (Z3,+) ks♠♣① ♥ T

3c s ♥ s t ♣r♦t♦♥ ♦♥t♦ T

3c ♦ t ♦♥① ♦ t ♠s ♦ k + 1

♣♦♥t♦st ♣rs ♥r ϕc ♥t♦♥ ♦r♥② ks♠♣① ♥ T33c

s ♥ ♥t s♠ ② ② t ♠s ♦ k + 1 ♣♦♥t♦st ♣rs ♥r ϕ3c tr♥t♦♥ tstrtr ♦s ♥♦t ♥♦ t ♦r♥ ♦♠♥ ♦ t s♣ ♦ tr♥t♦♥ t st♦rs sts r ♠♣♠♥t s tr♠♥s♦♥ ♥tr t♦rs t ♦♠♣r♥s ♥tr♦r ♦♥♥♥ ❲ ♥♦ ♣rs♥t t r♥t ss ♦ ♦sts ♥ t ♣r♦tr♥t♦♥s

s sr ♥ t♦♥ t tr♥t♦♥ t strtr st♦rs ♦♥② t s ♥t rts ♦ tr♥t♦♥ s ♥ t t t♦rs s♠♣s r ♥ ② ♣♦♥t♦st♣rs ♠st ♣t t r♣rs♥tt♦♥ ♦ t tr♥t♦♥ t strtr s ♦♦s♦ sr st♦r ♦r rts ♥ ♦r ♦sts t♦ r♣rs♥t ttrr♦♥ rt① r♣rs♥ts t ♦rt ♦ ♣♦♥t ♦ t ♥♣t ♣♦♥t st rt① ss ts r♠♥s♥♥ t ♦♥② st♦rs t ♣♦♥t ♦ t ♦rt tt s ♥ t ♦r♥ ♦♠♥ ♦ttt t ♦sts ♠st tt t♦ t s ♥ ♥♥♦t tt t♦ t rts s rt① ♠t r♥t ♦sts ♥ r♥t s s r

r strt♦♥ ♥ σ t rt① v s ♦st(00

) ♥ τ t rt① v s ♦st

(10

)

♦t tt ♦r ♥② ♦st o ∈ Z3 t ♦r ♣♦♥t♦st ♣rs (pi, oi) ♥ (pi, oi + o)

i = 0 . . . 3 ♥ t s♠ ♥r t rs♣t ♣r♦t♦♥ ♠♣ ♦r t ♠♣♠♥tt♦♥

Page 59: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

♥ t ♦♦♥ ♦♥♥t♦♥ ♥ ♦rr t♦ ♥♦♥ ② ♦ st♦r♥ s

♦♥♥t♦♥ t C t rts v0, . . . , v3 ♥ ♦rrs♣♦♥♥ ♦stso0, . . . , o3 t oi = (oix, oiy, oiz) ♥

mino0x, o1x, o2x, o3x = 0

mino0y, o1y, o2y, o3y = 0

mino0z, o1z, o2z, o3z = 0

♥tt② ts ♠♥s tt t r♣rs♥tt♦♥ ♦ t ♥ E3 s s ♦s s ♣♦ss

t♦rs t ♦r♥ t♦t ♦♥ ♦r ♥t ♦sts ♠ ♥r ϕc ♦ t s②s ♥tr② ♦♥t♥ ♥ t qr♥t x ≥ 0 y ≥ 0 z ≥ 0 s r

r strt♦♥ ♠s ♦ s ♦ ♣r♦ tr♥t♦♥ ♦r♥ t♦♦♥♥t♦♥

♦t tt st♦r♥ t♦♥ ♥♦r♠t♦♥ ♥ t s s rt t rs♣t t♦ ♠♠♦r②s s♦ r ♥trst ♥ ♥♥ r♣rs♥tt♦♥ tt s s ♦♠♣t s ♣♦ss ♦♦♥ ♠♠ s♦s tt ♦♥ t ♣r ♠♥s♦♥ ♦ t s♣ s s♥t

♠♠ ♦r ♥② tr♥t♦♥s ♦ ♦t T3c ♥ T

33c t s s♥t t♦ ♥♦

t ♦sts s♥ tr ts

Pr♦♦ ♠ ♦♦s r♦♠ stt♠♥t ♦ ♠♠ F (2) ♦♥ssts ♦ t ♦♣s♦ t ♥♠♥t tt ♥ rss ② ♦sts s♥ tr ts

♦t tt ♠♠ t② ♦s ♦r ♥② t♦rs t rt♥r ♥♠♥t♦♠♥

s ♦♥t♥s ♦r ♦sts rqr tr ts t♦ st♦r ♦r♥ t♦♠♠ ♥ t♦ st♦r ①tr ts ♣r ❲ rr♥t② s ♦♥ ♥s♥

♥t t♦ st♦r t ♦r ♦sts ♦ t s s♣♥t r♣rs♥tt♦♥ s ♦♥② st♦ st♦r ♦sts ♥ t tr♥t♦♥ t strtr ♦r ♦♠♣t♥ t ♦sts s tr♠♥s♦♥ ♥tr t♦r tt ♥ r♣rs♥t ♠ r r♥ ♦ ♦sts

♦r s♦♠ ♦ t ssq♥t② ♣rs♥t ♦rt♠s ♥ t♦ ♥ ♥♦r ♦sts♦♥sr ♥② tr♥t♦♥ ♦ T

3c ♦r T

33c ♦♥♥t♦♥ tr♠♥s ttrr♦♥

τ ♥ E3 t♦ t ♥♦♥ r♣rs♥tt♦♥ ♦ c ♥ t ♥② tr♥t♦♥ ♦ t

σ t ♥♦♥ r♣rs♥tt♦♥ ♦ ♥t t♦ c ♥ σ ♥ τ r ♥♦t ♥ssr②♥t ♥ E

3 s r

Page 60: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣r♦ tr♥t♦♥s

♥t♦♥ ♦r ♦st r s ♥ ♦st ζ s tt ϕc(σ, ζ) s ♥t t♦τ ❲ ts ♦st ζ ♥♦r ♦st r♦♠ τ t♦ σ

♥♦r ♦st ♥ tr♠♥ s ♦♦s t v ♦♥ ♦ t ♦♠♠♦♥ rts♦ τ ♥ σ ♥♦r ♦st s t r♥ t♥ t ♦st ♦ v ♥ τ ♥ t ♦st♦ v ♥ σ s r

r strt♦♥ ♥♦r ♦st r♦♠ τ t♦ σ s(10

)

♦r ♦sts r s ♥ t ♠♣♠♥tt♦♥ ♦ t r♠♠r♥ st♦st ♦r t ♣♦♥t ♦t♦♥ ♥ ♥ t ♠♣♠♥tt♦♥ ♦ ♥❴♦♥ts tt tr♠♥s t♦♥t r♦♥ ♦ ♣♦♥t

♦ t ♣♦♥ts tt r ♥♦t rts ♦ t tr♥t♦♥ s t ♦♦♥♥♦tt♦♥ t pv ♥♦t t ♣♦♥t ♦ t rt① v ♦ t tr♥t♦♥ ② ♦st o ♦ rt① v t rs♣t t♦ ♣♦♥t p ♠♥ t ♦st ♦ t ♥♣♦♥t pv ♥ t ♥② t ♥♣♦♥ts ϕc(p, 0) ♥ ϕc(pv, o)

rts

♦♠trrts ♦♥♣t ♦r ♣r♦ tr♥t♦♥s s ss♥t② t s♠ s ♦r tr♥t♦♥s ♠♥ ♥ s tt ♣rt ♥ ♦♥strt♦♥ ♥t ♣♦♥ts ♥ ♦rrs♣♦♥♥ ♦sts s r♠♥ts t♦♥② t♦ t rs♦♥ tt ts♦♥② ♣♦♥ts ♥ ♦rr t♦ ♣r♦ t ♥ ♣rts ♥ ♦♥strt♦♥s ♥ ♣trtt ♦rs s sr ② t ♦♦♥ ♣s♦♦ st♥

♦♦ ♣r♦❴♣rtP♦♥t ♣ P♦♥t ♣

st ♦ st ♦ ④

rtr♥ ♣rt♣ ♦ ♣ ♦

♣r♦❴♦♥strt♦♥ s ♥ ♥ t s♠ ② ♦t tt t ♥t ♦ t♦r♥ ♦♠♥ s rqr t♦ ♣r♦r♠ t ♦♠♣tt♦♥ ♦ t ♣rt ♦r ♦♥strt♦♥ ♦r♥ ♦♠♥ s ♦② ss♦t t t tr♥t♦♥ s♦ t s ♠♠r ♦ tss Pr♦❴❴tr♥t♦♥❴ ♥ ♥♦t ♦ t trts ss ❲ ♥♦ t trts sst ♣♦♥tr t♦ t ♦r♥ ♦♠♥ st♦r ♥ t ss Pr♦❴❴tr♥t♦♥❴

♣rts ♥ ♦♥strt♦♥s t♥ ♦♥② ♣♦♥ts ♦ ♥♦t rqr ② t♦rt♠ t ♣r♦ t♠ ♦r ♥② rs♦♥s ② ♥ ♦sts r③r♦ ♥ ts s ♥♦ tr♥st♦♥s t♦ ♦sts ♥ t♦ ♣r♦r♠ ♥ ts ♣rts♥ ♦♥strt♦♥s ♦ ♦♥sr② ss rt♠t ♦♣rt♦♥s

①t t♦♥ s sr ♥ t♦♥ t tr♥t♦♥s ♠♣♠♥tt♦♥ rqrs ①t ♣rts ♥ ♥♦ ①t ♦♥strt♦♥s ♦t♣t s ♦♠♥t♦r

Page 61: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

strtr tt ♦♥t♥s ♦♥② ♥♠♦ ♥♣t ♣♦♥ts ♦♠♣t♥ t ❱♦r♦♥♦ r♠s t ♦♥② s r ♥♦♥tr ♦♥strt♦♥s r ♥ ♥♠② ♦r ♦♠♣t♥ tr♠♥tr ♦ ttrr

♦r ♣r♦ tr♥t♦♥s t stt♦♥ s st② r♥t r♥ ♥ ♦rt♠ r♥s♦♠ ♣♦♥ts t♦ tr♥st ♥ ♦rr t♦ ♠ s♠♣s ♥ E

3 ♦r t♦♥ ♦♦♠tr ♣rts s r r♥st♥ ♣♦♥ts s ♦♠tr ♦♥strt♦♥ ♥

r strt♦♥ ♦ tst ♦♥ s ♦ t r♠r ♦ t ♣♦♥t q s p♠st tr♥st rst

t s ♥♦t ①t t ♦rrt ♦t♣t ♦ ♥ ♦rt♠ r♥ ♥ ♥ ts tr♠♥t♦♥ ♥♥♦t r♥t ♥ t ♦tr ♥ ♦ ♥♦t ♥t t♦ rqr ①t ♦♥strt♦♥s ♦r ♥②rs♦♥s ♦ ♦ ♦♥strt♦♥s rr♦♣ t tr♥st♦♥s ♥ ♣rt t♦♥s ♥♥ ♣rts t s ② ♥tr♦ t ♣rts t♥ ♣♦♥t♦st ♣rs sr♠♥ts ♦ tr♥st♦♥ ♦ t ♣♦♥ts s ♥♦ ♣rt ♦ t ♣rt t♦♥s ♠♥s t ♦♦r♥ts ♦ t tr♥st ♣♦♥ts r ♥r r♣rs♥t ♥ ♠♠♦r② t♦♥② trt s②♠♦② ♥ ts ② t ♥♦♥ ♥ ② ♥t t♥qs ♦r①t ♣rt t♦♥ ♥ ♣♣ ♦r t s♠ rs♦♥ ♥ ♦♠♣t♥ ♥ T

33c

t ♣♦♥ts ♦ts Dc st♦r t ♦♦r♥ts ♦ t ♦rrs♣♦♥♥ ♣♦♥ts ♥ Dc ♥ rss♥ ♥ ♦st ♦♦r♥ts ♦ ♣♦♥ts ♦ts ♦ Dc r ♥r ♦♠♣t ①♣t②

♦r♥ s♣s

r sr ♦ ♦r ♠♣♠♥tt♦♥ ♥s ♦r♥ s♣s ♥ ♦ ♥♦♥rs♦♥ t♥ r♥t ♦r♥ s♣s ♦t tt ♥ ♥r tr♥t♦♥s ♦ s♠♣♦♥t sts rqr ♦♠♣tt♦♥ ♥ T

33c rs ♦r r ♣♦♥t sts ♥ ♦♠♣t ♥ T

3c

♦ ♦♥ r② ♠♣♦rt♥t ♠♣♠♥tt♦♥ ss s tt tr s♦ ♥♦t ♥② ♦r ♦r♥♥ ♦r♥ s♣s ♥ ♦♠♣t♥ ♥ T

3c t♦t t♦♥ ♦♣s

♥ ♦rr t♦ ♦♠♣t ♥ T33c ♦♣s ♦ ♣♦♥t r ♥srt ♠♠r tt ♥ T

33c

rts t r♣rs♥tt ♥ Dc ♦r♥ rts ♥ ♦tr rts ♣r♦♦♣s

♦♣② st ❲♥ ♦♠♣t♥ ♥ T33c rts r♣rs♥t ♦rts ♥r t t♦♥ ♦ t

r♦♣ (3Z3,+) ♦ ♣♦♥t ♥ D3c ♦ ♥ ♦rt r♣rs♥t ② rt① ♦s ♥♦t ♥ssr②

♥ Dc ♦r t ♥♣t ♣♦♥t st ♦ t ♦rt♠ s ♦♥t♥ ♥ Dc ♦r♥ t♦t♦♥ t tr♥t♦♥ t strtr st♦rs ♦r rt① t ♦♦r♥ts ♦ ♣♦♥t ♥ D3c ♦r♥ t♦ t♦♥ t ♦♠♣tt♦♥ ♦ t ♣♦♥t ♦♦r♥ts ♥ D3c

♦ ♣r♦ ♦♣② ♦ ♥ ♥♣t ♣♦♥t s ♦♠tr ♦♥strt♦♥ ♥ ♦rr t♦ ♦ ts♦♠tr ♦♥strt♦♥ st♦r ♦r ♣r♦ ♦♣② t ♦rrs♣♦♥♥ ♥♣t ♣♦♥t p♥ Dc ♥ ♦♣② st s s tt ϕc(p, s) s t ♣r♦ ♦♣② ♥ D3c ♦♣② sts r

Page 62: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣r♦ tr♥t♦♥s

♦♥② rqr ♥ ♦♠♣t♥ ♥ T33c s♦ ♦ ♥♦t st♦r t♠ ♥ t tr♥t♦♥ t

strtr t♦ ♦ ♠♠♦r② ♦r ② r st♦r ♥ s♣rt t strtr ♥ ttr♥t♦♥ ss ts s sr ♦ ♦sts ♦♣② sts r ♠♥ts ♦ Z

3♥ t ♠♣♠♥tt♦♥ rs t ♦st ss t♦ r♣rs♥t ♦♣② sts

t strtrs r sr t strtr t♦ r♦r t ♦♣② st ♦ ♥rt① s t strtr t♦♥② st♦rs t ♥♦r♠t♦♥ rts r ♣r♦ ♦♣s ♦ ♦tr ♥ ♥♦r♠t♦♥ tt s ♥♦t ♦♥t♥ ♥ t tr♥t♦♥ tstrtr tr ❲ t♦ s st♠♣ t ❱rt①❴♥ s ② t②♣ ♥st♣r❱rt①❴♥♦♣②❴st s t②♣ t♦ rtr ♦r rt① tt s♥♦t ♥ ♦r♥ rt① ts ♦rrs♣♦♥♥ ♦r♥ rt① ♥ t ♦♣② st ❲ ts♠♣ ♦r♥❴♠♣ s t t② ♦rrs♣♦♥s t♦ t ♠t♠t ♥t♦♥ ♦ t♦r♥ ♠♣ s ♥t♦♥ t s st♦r ♥ t ss Pr♦❴❴tr♥t♦♥❴ r ♦r ♥ strt♦♥ ♦ t s ♦ t ♦r♥❴♠♣

r strt♦♥ ♦r♥❴♠♣ ♠♣♠♥ts t rr♦ rt♦♥

♦r s♦♠ ♦rt♠s ♦ ♥♦t ♦♥② ♥ t♦ ♥ t ♦r♥ ♦♣② r♦♠ ♥ rt①t ♠st s♦ ♥ ♣r♦ ♦♣s ♦ ♥ ♦r♥ rt① r s ♥♦tr ♠♣tt st♦rs ♦r ♦r♥ rt① ts ♣r♦ ♦♣s ② t②♣ ♦ ts ♠♣ s ♥❱rt①❴♥ t t②♣ s stt♦r❱rt①❴♥ r t ♦♣② sts r♠♣t② ♥♦ s tr♥r② ♥♠rs ♥ t ♥① ♦ t ♣r♦ ♦♣② ♥ t t♦r t ♦♣② t ♦♣② st (i, j, k) s st♦r s t t♦r ♠♥t ♦ ♥① i ·32 + j ·31 +k ·30❲ ts ♠♣ rrs❴♦r♥❴♠♣

♣ tr ♦ t ♥t ❲ ♠♣♠♥t rtr♦♥ ♥ ♦rr t♦ ♥ t♦ ♦♥rt t tr♥t♦♥ t♦ T

3c ♦ ♦ ♦r ♥ ♦♠♣t♥ ♥ T

3c

♠♥t♥ ♥ ①r② t strtr tt ♦♥t♥s s tt r t♦♦ ♦♥ ♦r♥ t♦rtr♦♥ s t strtr ♦♥② ♦♥t♥s t ♥ ♦♠♣t♥ ♥ T

33c ♦trs

t s ♠♣t② t ♦rs ♥ t ♦♦♥ ② s t strtr s st♠♣ t ②t②♣ ❱rt①❴♥ ♥ t②♣ stst❱rt①❴♥ ♥ s t♦♦ ♦♥♦♥ ♦ ts rts s st♦r s ② ♥ t ♦tr ♦♥ s ♦♥t♥ ♥ t ♦rrs♣♦♥♥st ❲ ts t strtr ♦♥❴s❴st s r

♥ ♦rr ♥♦t t♦ st♦r s t rqr ♦♠♣rs♦♥ ♥t♦♥ ♦r ❱rt①❴♥s♥ ♥ t ♦♥♥t♦♥ tt ❱rt①❴♥ ♥ ② s ②s s♠r t♥ ♥② ♦ t❱rt①❴♥s ♥ t ♦rrs♣♦♥♥ st ♦r t ♦♠♣rs♦♥ ♥t♦♥ ♦♠♣r t♠♠♦r② rsss ♦ t ❱rt①❴♥s

❲♥ r ♦♠♣t♥ ♥ T33c t♠ ♥srt ♥ ♣♦♥t ♦r r♠♦ rt①

♣t t ♦♥❴s❴st ♥ s ♦ ♣♦♥t ♥srt♦♥ r♠♦ s ♦ t

Page 63: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

r ♦♥❴s❴st

♦♥t r♦♥ tt r ♦♥t♥ ♥ t ♦♥❴s❴st ♥ ♦r ♦ t ♥② ♥srt s tr t s ♦♥r t♥ t trs♦ ♥ rtr♦♥ ♥ s♦ ♥srt t ♥t♦ t ♦♥❴s❴st ♦t tt ts ♣♣r♦ r♠♦s ♥ r♥srtst s♠ s r♦♠ t ♦♥r② ♦ t ♦ s r♥♥t ♦r t s qtt t♦ tst ♦r ♥ tr t s ♦♥ t ♦♥r② ♦ t ♦ t tr♥s ♦tt♦ str t♦ r♠♦ ♥ r♥srt s♦♠ s r♥♥t② rtr t♥ tst♥ ♦r ♦t♠ tr t② ♦♥ t ♦♥r② ♦ t ♦

♥ s ♦ rt① r♠♦ ①t② t s♠ ♣♣r♦ s s

♦♥rs♦♥ r♦♠ T33c

t♦ T3c ♥ t ♦♥❴s❴st s ♠♣t② t rr♥t tr♥

t♦♥ ♥ ♦♥rt t♦ T3c ♦ ♦ s♦ trt ♦r t♠s ♦r s ♥ ♦♥ ♦r

rts s s♦ r

r s tt t s r t t② r ♥♦t ♥♦♥t rs♣t t♦ t ♦r♥ ♦♠♥ ♦ T

3c ♥ t s♥s ♦ ♦♥♥t♦♥

♦r ♥♠r s rrt t ♥♦r ♣♦♥trs t♦ t ♥ ♥♦rs ss♦♥ ♥ r t② ♣♦♥t t♦ ♠r ♥ ♥♦rs ♥ ♦♥ s♥ t ♦r♥❴♠♣

♦t tt rts t t② r ♥♦t ♦r♥ rts t ♣r♦♦♣s ♦r ♥♠r s rrt t rt① ♥s tt ♣♦♥t t♦ rtstt r t♦ t t♦ t ♦rrs♣♦♥♥ ♦r♥ rts

t ♠r s

❱rt① t rts tt r ♥♦t ♦r♥ rts

♦♥rs♦♥ r♦♠ T3c t♦ T

33c

♦r♥ t♦ rtr♦♥ ♥ ♦♠♣t♥ ♥ T3c

♥r ♥ t♦ st t♦ T33c

st ♣ ♥srt♥ ♣♦♥ts ♦r rt①r♠♦ ♥ ♠ t ♥ssr② t♦ st t♦ T

33c ♦ r♥ rt① r♠♦ ♥

♥ ♦♠♣t♥ ♥ T3c ♥ t♦ tt t ♥② rt s ♦ ♥♦t s

tt r ♦♥r t♥ t trs♦ ♥ rtr♦♥

Page 64: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣r♦ tr♥t♦♥s

r strt♦♥ ♦♦r s t t rts tt t r ♥♦t r♥ rr♦s ①♠♣r② ♥t t ♥ ♥② rt♦♥s

♦♥rs♦♥ r♦♠ T3c t♦ T

33c

tr♥s ♦t t♦ ♠♦r ♦♠♣t t♥ t ♦♥rs♦♥r♦♠ T

33c

t♦ T3c sr ♦ t s ♦♥ ♥ t ♦♦♥ ② rst rt ♦♣s

♦ rt① ♥ ♦♥strt t ♦r♥❴♠♣ ♥ t rrs❴♦r♥❴♠♣ trt♦r s ♥ st♦r t rt① ♦sts ♥ ♥♦r ♦sts ♥ s♦♠ t♠♣♦rr② tstrtrs ♦ rt ♣r♦ ♦♣s ♦ ♦t♥♥ tr rts r♦♠ trrs❴♦r♥❴♠♣ s♥ t rt① ♦sts r♦♠ t t♠♣♦rr② t strtr ♦ttt t ♦r♥ s r ♦♠♣t② ♦♥t♥ ♥s t ♦r♥ ♦♠♥ ♦ T

33c s

t② ♥♦ tr♥ t♦ s t ♦sts ③r♦ ♥ t ♦♥s tt ♥♦♥③r♦ ♦sts♦r rts ♦ ♥♦♥③r♦ ♦sts ♠st r♣ ② tr ♣r♦ ♦♣s tt rs♣t ♦♣② st ♦r♥ t♦ t rrs❴♦r♥❴♠♣ t r♠♥s t♦ st t♥♦r rt♦♥s ♦ ♦t t ♥② rt s ♥ t ♦r♥ s t ♣♦♥trs♦ t rts t rt① ♦sts ♥ t s ♥ ♥② t♦ st ♣ t ♦♥❴s❴st

P♦♥t ♦t♦♥

♣♦♥t ♦t♦♥ s r♥t t♦ ♦r ♦♥② ♦r ♥♣t ♣♦♥ts ♥ ♥ t ♦r♥ ♦♠♥

r♠♠r♥ st♦st sr ♥ t♦♥ ♦rs ♥ ♣r♦ tr♥t♦♥s s s t r♣rs♥tt♦♥s ♥ E

3 ♦ t s♠♣s ♦r t ♦♠tr tsts t♠ r♦♠ ♦♥ t♦ t ♥①t ♥ t♦ ♣ tr ♦ t ♥♦r ♦sts♥ ♦rr t♦ ♠♥t♥ t ♦st ♦ t ♥♣t ♣♦♥t t rs♣t t♦ t rts ♦ t rr♥t s r

s strt t r♥♦♠ ♦ t tr♥t♦♥ ts strt♥ s ♥♦♥♠♣t② ♥trst♦♥ t t ♦♥r② ♦ t ♥♠♥t ♦♠♥ t ♥ ♣♣♥ ttt s r② ♦s t♦ t ♣♦♥t t♦ ♦t ♦r ♥ ♦♥t♥s t t ts ♥♦♥ r♣rs♥tt♦♥ ♥E

3 ♦r♥ t♦ ♦♥♥t♦♥ ♣♣rs ♦♥ t ♦♣♣♦st s ♦ t ♥♠♥t ♦♠♥s ♥ tt s② ② tst♥ tr t strt♥ s t st ♦♥ ♥♦♥③r♦ ♦st ♥ ts s ♣♥♥ ♦♥ t ♦♦r♥ts ♦ t ♣♦♥t strt t ♣♦♥t♦t♦♥ t t ♣r♦ ♦♣② ♦ t t t ♦♣♣♦st s ♦ t ♥♠♥t ♦♠♥ sr s ♣r♥ts t r♦♠ trrs♥ t ♦ ♦♠♥ t strt♥ ♥ t ♦♥t♥♥ t ♣♦♥t r t② ♦s s s ♦rs s♣② ♥s♥ t s♣t s♦rt♥ s t♦♥

Page 65: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

r strt♦♥ ❲♥ trrs♥ t s t ♦st ♦ t ♣♦♥tt rs♣t t♦ t rr♥t ♥s r♥ tr♥ strt♥ r tr♥ ♦♥t♥♥ t qr② ♣♦♥t q

r strt♦♥ s t ♣♦♥t s ♥ t t ♦ t ♥♠♥t ♦♠♥ strt t t ♠♦r ♣♣r♦♣rt ♣r♦ ♦♣② ♦ t ♥t r♥ tr♥strt♥ r tr♥ ♦♥t♥♥ t qr② ♣♦♥t q

P♦♥t ♥srt♦♥

r ♦♠♣t♥ ♥ T3c t♥ t ♣♦♥t ♥srt♦♥ ♥ ♠♣♠♥t ♥ ①t② t s♠

② s sr ♥ t♦♥ ♦r ♥ T33c t♥ ♣♦♥t ♠st ♥srt

t♠s ② t ♥srt♦♥ ♦rt♠ s sr ♥ ♦rt♠ ♥ t♦♥② ♠st♠♥t♥ t ♠♣s ♦r t ♣r♦ ♦♣s ♦ rts s s t ♦♥❴s❴st

s sr ♥ t♦♥ t ♥srt♦♥ st♣ rst ♥ts t s tt r ♥♦♥t t t ♥② ♥srt ♣♦♥t ♥ t ts ts s ♥ ♦ ♥ t tstrtr tt s r ② ♥ tr♥s t t ♥ ♣♦♥t s rt① t ♦♥r② ♦t ♦ ♥ t ♦♥r② ♦ t ♥♠♥t ♦♠♥ ♥♦♥♠♣t② ♥trst♦♥ s♦♠♦ t ♥ s ♥ t ♦ rts t ♥♦♥③r♦ ♦sts s r t♦ ♣♦ss t♦ ♦♠♣t ts ♦sts ② ♥ tr♦ t s ♦ts t ♦ ♣♥ tr ♦ t ♥♦r ♦sts t ts ♣♣r♦ ♦ qt ♦st② ♥tr♠s ♦ r♥♥♥ t♠ ❲ s t ♦♦♥ ♠♦r t♠♥t t ss s♣♥t♣♣r♦

• r♥ t st♣ ♦ ♥t②♥ s ♥ ♦♥t t t ♥ ♣♦♥t ♦♠♣t t♦sts ♦ rt① ♦ ♥ ♦♥t t rs♣t t♦ t ♥ ♣♦♥t s

Page 66: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣r♦ tr♥t♦♥s

♦sts r t♠♣♦rr② st♦r ♥ t rts

• tr ♥ rt t ♥ s ♦♥② ♥ t♦ t t st♦r ♦sts r♦♠ trts t♦ ♦rrt② st t ♦sts ♥ t s

• tr ♣♦♥t ♥srt♦♥ t ♦sts tt r st♦r ♥ t rts t♦ r ♦♥ ♦rr t♦ ♥♦t ♥trr t tr ♣♦♥t ♥srt♦♥s

s ♣♣r♦ rqrs t♦ st♦r ♦♥ ♦st ♥ rt① ♥ ts rqrs t s ♦ s♦♠①tr ♠♠♦r② ♥ tt t ♥♠r ♦ rts ♥ tr♥t♦♥ s ♥r② s♠♦♠♣r t♦ t ♥♠r ♦ s s ♠♠ ts ♠♠♦r② ♦r s ♣ts s t ♦♥② s r ♦sts r tt t♦ rts

r strt♦♥ ♦ ♦♦r ♥s s♦ t ♦♥r② ♦ t ♦r♥ ♥srt♦♥ ♦ t ♣♦♥t ♦sts tt t♦ t ♦s rts r s♦♥ t②♥t ♦ t♦ tr♥st t rts ♥ ♦rr t♦ t t s ♣♦②♦♥

♦t tt ts ♣♣r♦ ♦♥② ♦rs t ♦ s ♦♠♦♠♦r♣ t♦ ♦s t ♥♦♥ ♦ s♠♣s ♦ t str ♦ t ♥② ♥srt ♣♦♥t s t strtrtr t ♣♦♥t ♥srt♦♥ s s♠♣ ♦♠♣① t♥ t ♦ s ♦♠♦♠♦r♣ t♦ ♠♠ ♥ ♦r♠

❱rt① r♠♦

♥ ♣r♥♣ t ♦rt♠ ♦r r♠♦♥ rts ♦rs ♥ t s♠ ② s sr ♥t♦♥

♠♠r tt t rst st♣ ♦ t rt① r♠♦ ♦♥ssts ♥ t♥ ttrr tt ♦♥t♥ t rt① r♦♠ t tr♥t♦♥ ②♥ ♦ ② ♦r♠ ♣ ts ♦ s ②s ♦♠♦♠♦r♣ t♦ ♥tr♦r ♦ t ♦ ♠st tr♥t ♥ ts tr♥t♦♥ ♠st s ♥ t rr♥t t strtr s t♦ s ♦♠♦♠♦r♣ t♦ t tr♥t♦♥ ♦ t ♦ s ♦♠♣t s t ♥②tr♥t♦♥ ♦ E

3 ♥ ② t rts ♦ t ♦ s s ♦♥ s♥ t tr♥t♦♥ ♠♣♠♥tt♦♥

r st s ♥ ♠♣♠♥tt♦♥ ss tr♥t♦♥ ♦ t ♦ ♠st s♥t♦ t ♦ rt ② t♥ t rt① r♦♠ t ♣r♦ tr♥t♦♥ ♦r ttr♥t♦♥ t strtrs ♦ tr♥t♦♥ ♥ ♣r♦ tr♥t♦♥r ♥♦t t②♣ ♦♠♣t t s s ♦r t ♣r♦ tr♥t♦♥s r♥t rt①♥ sss ♦r st♦r♥ t ♦sts r rqr ♦ t s ♥♦t s♥t t♦ ♦♣② t

Page 67: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

♣r♠ts r♥ t s♥ ♣r♦ss t t② ♠st s♦ ♦♥rt t♦ ♦ts ♦ trt t②♣

t♦♥② ♥ ♦♠♣t♥ ♥ T33c

t ♦♥❴s❴st ♥s t♦ ♣t s s t ♦r♥❴♠♣ ♥ t rrs❴♦r♥❴♠♣

❲♥ ♦♠♣t♥ ♥ T3c t♦ r② tr r♠♦ tt tr r ♥♦ s tt

r t♦♦ ♦♥ ♦r♥ t♦ rtr♦♥ trs t tr♥t♦♥ s t♦ ♦♥rtt♦ T

33c

ss

s sr ♥ t♦♥ t rts st♦r t ♦rrs♣♦♥♥ ♣♦♥t ♦♦r♥ts t ♦♦r♥ts ♦ t rt① ♦ ♥① ♥ ♥ ss ② rt①♣♦♥t♦r ∈ 0, 1, 2, 3 ♦r ♥ ♦rr t♦ ♣r♦t s♠♣① ♥t♦ E

3 t ♦sts ♥ t ♥t ♦ t ♦r♥ ♦♠♥ ♠st t♥ ♥t♦ ♦♥t r r t♦ t♥s t♦ ♦♥sr ♦r♥ ♦♠♥ ♦ T

3c s r♥t r♦♠ t ♦r♥ ♦♠♥ ♦ T

33c

❲♥ ♦♠♣t♥ ♥ T33c t ♣♦♥t ♦♦r♥ts ♦ts ♦ Dc ♠st ♦♠♣t s♥ t

♦r♥❴♠♣ ♦ ts t♥ts r♦♠ t sr ♥tr♦ ♥ ♠♠r♥t♦♥ ♣♦♥t t♦ t ♣r♦ tr♥t♦♥s t♦ rt①♣♦♥t ♥♥♦ r♣ ② t♦ ts♣♦♥t ♥st ♦ t♥ t ♣♦♥t ♦♦r♥ts r♦♠ t tr♥t♦♥ t strtr rt② t ♥t♦♥ ♣♦♥t s♦ tst ♦sts r♦♠ t t strtr ♥ t ♣♦♥t ♦♦r♥ts ♥ ♦♣② sts r♦♠ t♦r♥❴♠♣ t tr♥t♦♥ s r♣rs♥t ♥ T

33c

♦ ss t s♠♣s ♦ t tr♥t♦♥ t trt♦rs ♥ rt♦rs ♦ t tr♥t♦♥ t strtr r ♦r ♥♦t tt t tr♥t♦♥ t strtr♦s ♥♦t t ♥♦r♠t♦♥ tr t st♦rs tr♥t♦♥ ♦ T

3c ♦r ♦ T

33c t

tr♥t♦♥ s r♣rs♥t ♥ T33c t trt♦r rtr♥s ♦♣s ♦ s♠♣① t s

♥♦t ♣♦ss t♦ tr ♦t ♦♣s t t t strtr s s♦ s ♠t♠trs♦♥ ❲ ♦♠♣t ♥ T

33c

s t tr♥t♦♥ ♦s ♥♦t ①st ♥ T3c trt♦rs

♦ rtr♥ ♦♥② ♦♥ ♦♣② ♦ s♠♣① ts ♦ t♦ ♥♦♥sst♥s ♥ t♥② ♥ ♥♥ rt♦♥s s rtr♥ s♠♣s ♦ ♥♦t ♦r♠ tr♥t♦♥s r ♦r ♥ ①♠♣ ♦r s♦♠ ♣♣t♦♥s t s s t♦ ♦♥② ♦♥ ♦♣② ♦ s♠♣① ♥ t rtr♥ st ♦ s♠♣s ♦s ♥♦t ♦r♠ tr♥t♦♥

r strt♦♥ ♥ trt♦r rtr♥♥ ♦♥② ♦♥ ♣r♦ ♦♣② ♦ s♠♣①rtr♥s ♦r ♥st♥ t pqr t ♦♥② ♦♥ ♦ ts tr ♥t s

♦ ♣r♦ s ♥t♦♥t② t♦t ♥♦♥sst♥s s♦♠ ♦♠tr trt♦rs

Page 68: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣r♦ tr♥t♦♥s

tt ♦♥② ♦t♣t s♠♣s t♦t ♥② ♥ ♥♥ rt♦♥s ♥ ♣r♦♠s t♦s s♦♥ ♥ r ♥♥♦t ♦r s ♦♠tr trt♦rs ①st ♦r ♦r t②♣s♦ s♠♣s ♣♦♥ts s♠♥ts tr♥s ♥ ttrr r r ♦r r♥t ♦♣t♦♥st♦ s♣② s♠♣s rtr♥ s s♦ r

• trts ♦r t s♠♣s tt r st♦r t s♦s t s♠ ♦rs t trt♦rs r♦♠ t tr♥t♦♥ t strtr

• ❴❱❴ trts ♦r s♠♣s tt ♥♦♥♠♣t② ♥trst♦♥t t ♥♠♥t ♦♠♥ ♦ t t t♦rs t tr♥t♦♥ s st♦r ♥ ♦♣s ♦ t ♦r♥ ♦♠♥ ♥ s ♦ T

33c s ♠♥s tt t s♠♣s tt

♥trst t ♦♥r② ♦ t rr♥t ♥♠♥t ♦♠♥ rtr♥ srt♠s

• ❯❯ trts ♦♥② ♦r t ♦r♥ ♦♣② ♦ s♠♣①

• ❯❯❴❱❴ trts ♦♥② ♦r t♦s s♠♣s tt ♥♦♥♠♣t② ♥trst♦♥ t t ♦r♥ ♦♠♥ s ♦r ❴❱❴ ♦♥r② s♠♣s rtr♥ sr t♠s

r ♦r ♠♦s ♦r t ♦♠tr trt♦rs ♦♣ t ♦♣rt ❴❱❴ ♦tt♦♠ t ❯❯ ♦tt♦♠ rt ❯❯❴❱❴r t tr♥t♦♥ s r♣rs♥t ♥ T

33c

♥ t ttrr ♦t♣t ② t trt♦rs rs♦♥

♣t♠③t♦♥s

r r sr ♦♣t♠③t♦♥s ♦r tr♥t♦♥ ♦♠♣tt♦♥ s sr ♥ t♦♥ s ♦♣t♠③t♦♥s ♥ ♣t t♦ ♣r♦ tr♥t♦♥s

Page 69: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

rr② s sr ♥ t♦♥ t tr♥t♦♥ rr② ♠♥t♥s ♥t♥♠r ♦ ②rs ♦ tr♥t♦♥s r t ♣♣r ②rs r ♦rsr t♥ t ♦r ②rs♦ ♦♥♥t t ②rs rt① s ♣♦♥tr t♦ ts ♦rrs♣♦♥♥ rt① ♥ t ②r♦ ♦♥ ♥ ♥ t ②r ♦ ♣ tr s ♦♥ ♥ t ②r ♦ ♦t tt rt① s ♦rrs♣♦♥♥ rt① ♥ t ②r ♦ s♦ t ♦♥♣♦♥tr ②s ♣♦♥ts t♦s♦♠ rt① ①♣t ♦r rts ♥ t ♦r♠♦st ②r

♦r ♣r♦ tr♥t♦♥s t s ② ♣r♦ tt t ♦rsr ♣♣r ②rs rr♣rs♥t ♥ T

33c

t ♥r ♦r ②rs r r♣rs♥t ♥ T3c ❲ ♥① t ②rs

r♦♠ ♦tt♦♠ t♦ t♦♣ t ♦r♠♦st ②r s ♥① t ②r i t ♣♣r♠♦st②r r♣rs♥t ♥ T

3c s♦ ②r i + 1 s r♣rs♥t ♥ T

33c ♥ t ♣r♦ ♦♣s

♦ ♦r♥ rts ♥ ②r i + 1 ♦ ♥♦t ♦rrs♣♦♥♥ rts ♥ t ♦r ②r i♥ ts tr ♦♥♣♦♥tr s ♥♦t st ♦ ♦ ♥♥ ♦♥♣♦♥trs t t♦♥♣♦♥trs ♦ ♣r♦ ♦♣s ♣♦♥t t♦ t ♦r♥ rt① ♥st Pr♦ ♦♣s ♦♥♦t ♣♣♦♥trs s t② r ♥♦t rqr s r

r strt♦♥ ♣ ♥ ♦♥♣♦♥trs ♦ ♣r♦ ♦♣s ♣♦♥t t♦ t ♦r♥rt① ♦♥ ②r ♦r

♣t s♦rt♥ s♣t s♦rt♥ s sr ♥ t♦♥ ♥ rs t♦t♥② ♠♦t♦♥ ♦t♣t sq♥ ♦ t s♣t s♦rt♥ s t ♣r♦♣rt② tt t♦♣♦♥ts tt r ♦s ♥ t sq♥ s♠ ♥ st♥ ♥ E

d s t ♥♣t♣♦♥t st ♦r t ♣r♦ tr♥t♦♥ s ♥ Dc s sst ♦ E

d ts ♣r♦♣rt②r♠♥s tr

t♦♥ ♥t♦♥t②

❲ ♣r♦ s♦♠ t♦♥ ♥t♦♥t② ♥t♦♥t② tt s ♥♦t rqr t♦ ♦♠♣tt ♥② tr♥t♦♥ ts t s s ♦r t sr ♥tr

♦r ♦♥rs♦♥ t♥ ♦r♥ s♣s s s♦♥ ♥ t♦♥ t rtr♦♥ s s♥t t ♥♦t ♥ssr② t♦ tr t rr♥t ♣♦♥t st ♥s ♥② tr♥t♦♥ ♦ T

3c t s ♣♦♥t st ♥ ♥ tr♥t♦♥ ♥ T

3c ♥ rtr♦♥ s

♥♦t ♥ssr② ♦♥t♦♥ s ♥ ② ♦r♠ ♦r t s ♣♦ss tttr ♥ ♣♦♥t t♦ t ♣♦♥t st t ♦s ♥♦t ♥ tr♥t♦♥ ♥ T

3c ♥②♠♦r

rtss ♦r tr♥t♦♥ tt s ♥♦t ♦♥ t♦ ♥ ♥②♠♦r t ♠t s t♦♦♥rt t r♦♠ T

33c

t♦ T3c ♥t♦♥ s❴tr♥t♦♥❴♥❴❴st ♠♣♠♥ts t

Page 70: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣r♦ tr♥t♦♥s

tst ♦r t ♦♥t♦♥ ♥ ♦r♠ ♥t♦♥s ♦♥rt❴t♦❴❴st❴♦r♥♥ ♦♥rt❴t♦❴❴st❴♦r♥ ♥ s t♦ ♦♥rt t♥ T

3c ♥ T

33c

❱♦r♦♥♦ r♠ s ♥ t ♥② tr♥t♦♥ ♣r♦ ♥t♦♥t②♦r ♦♠♣t♥ ❱♦r♦♥♦ r♠s ♦t tt t ♦♠♣tt♦♥ ♦ ❱♦r♦♥♦ r♠s rqrs♦♠tr ♦♥strt♦♥s ♥ ts s ①t ♦♥② t r♥ ♣r♦s ①t ♦♥strt♦♥s

♦ rtr♥ t ❱♦r♦♥♦ r♠ ♦♥② ♥ ♥t♦♥s tt ♦r ♥ s♠♣① rtr♥ts s ②s t ♦♦♥ t②♣s ♦ ♦♠tr ♦ts

♥② ❱♦r♦♥♦

P♦♥tt ♠♥t P♦②♦♥❱rt① P♦②r♦♥

♦t tt ♣♦②♦♥s ♥ ♣♦②r r ♥♦t s♠♣s ♥ ♦ ♥♦t ♦♥st♥t s③ s♦tr r ♥♦ r♥ ♦ts ♥ st t♦ r♣rs♥t t♠ ♥ t ♥②tr♥t♦♥s ♦♥② ♥t♦♥s ♦r ts ♥ s r s s♥t t♦sr t ❱♦r♦♥♦ r♠ s ♦ rts ♥ s ♥ ♦♥strt s②r♦♠ ts ♦t♣t ♥ t ♣r♦ s t ♥t♦♥s ♦r ts ♥ s r s♥tt♦♦ ♦r sr♥ t ♣r♦ ❱♦r♦♥♦ r♠ ♦r ♦r t ♣♦②♦♥s ♥ ♣♦②r s♦♠ rts ♠t ♥ t♦ tr♥st ♥ ♦rr t♦ ♠♣ t ♣♦②r♥ ♣♦②♦♥s ♥t♦ E

3 t s t ♠♦r ♥♦ t♦ ♦♠♣t t ♦sts tt tr♠♥ts tr♥st♦♥s s♥ t ♥ t ♥t♦♥s ♦♥② r♦r s♦ ♣r♦ ♥t♦♥s ♦r rts ♥ s tt s t ♥♥ rt♦♥s ♥ t ♥②tr♥t♦♥ t♦ r♦♥strt t rt① ♦sts ♦ t ♣♦②r ♥ ♣♦②♦♥s s s ♠♦r♥t t♥ ♥ ♦ ♣♣r♦ s♥ t ♥t♦♥s ♦r ts ♥ s ♦♥② ♥t♦♥s ♦r rts ♥ s ♦t♣t t rs♣t ♦ts s ♣♦♥t sts tr♦ ♥♦t♣t trt♦r s t ♦♠♣tt♦♥ ♦ ❱♦r♦♥♦ rt① rqrs ♦♠tr ♦♥strt♦♥tr s ♥♦ rs♦♥ t♦ ♦ rtr ♦♠tr ♦♥strt♦♥s ♦r tr♥st♥ ♣♦♥ts s rtr♥ t tr♥st ♣♦♥ts ♥st ♦ ♣rs ♦ ♣♦♥ts ♥ ♦sts

❲ ♠♣♠♥t ♣r ♥t♦♥ ♣r♦❴r♠♥tr tt ♦♠♣ts t r♠♥tr ♦r ♥ ♥ rtr♥s t ♣♦♥t ♥s t ♦♠♥ ♥ ♥ ♦st tt s♣st ♣r♦ ♦♣② ♦ ts ♣♦♥t tt ♦rrs♣♦♥s ♦♠tr② t♦ t r♠♥tr ♦ t♥♦♥ r♣rs♥tt♦♥ ♦ t ♥♣t ♥ E

3 s ♦st ♥♥♦t ♥rr rt②r♦♠ t ♦sts ♦ t s tr s ♥♦ rt♦♥ t♥ t ♦st ♦ r♠♥tr♦ ♥ t ♦sts ♦ t ts s r s ♦♠tr tsts ♠st ♣♣ t♦ ♥ t rt ♦st ♥ −1, 0, 13

t② ♥t♦♥s t♥ ♦r s ♦♦s

tr♥s t r♠♥tr ♦ t ♥sDc s ♦♠♣t ② ♣r♦❴r♠♥tr

t tr♥s t s ♣r ♦ ts ♥♣♦♥ts r♣rs♥t ② ♣♦♥t♦st ♣rs♦♦♥ ♦♥♥t♦♥

♦ ♥ s ♣♦②♦♥ ❲ rtr♥ ♥ ♦rr st ♦ ♣♦♥ts tt ♥ts ♣♦②♦♥ ♦t tt ts ♣♦♥ts ♦ ♥♦t ♥ssr② ♥s t ♦♠♥ ❲t t ♣♦②♦♥ s ♦♦s rt ♦r s ♥♥t t♦ t ♦r ♦♠♣t t r♠♥tr ♥ t rqr ♦st t rs♣t t♦ ♦♥ ♦ trts ♦ t ♥♣t s♥ t ♣r ♥t♦♥ ♣r♦❴r♠♥tr

Page 71: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

r strt♦♥ ♦sts ♦ tr♥ ♦ ♥♦t tr♠♥ t ♦st ♦ tsr♠♥tr

❱rt① ♦ rt① s ♣♦②r♦♥ ❲ rtr♥ st ♦ ♣♦♥ts tt ♥ ts♣♦②r♦♥ s tr ♦♥① s ♦ ts ♣♦♥ts ♦ ♥♦t ♥ssr② ♥s t ♦♠♥ t r ♦s♥ s tt tr ♦♥① s ♣r♦t♦♥ ♦ t ♦ t rt① ♥t♦ E

3 ♥ ♦rr t♦ ♦t♥ t ♣♦②r♦♥ ts t ♥②rt♦♥s ♥ ①trt r♦♠ t ♥② tr♥t♦♥

♦♠♣①t②

s s♥ ♥ t♦♥ ♦rt♠ s t s♠ r♥♦♠③ ♦rsts ♦♠♣①t②s t ♦rt♠ ♦r ♦♠♣t♥ ♥② tr♥t♦♥s ♥ E

3 ♦r ts s ♥♦t tr♦r t ♠♣♠♥tt♦♥ s ①♣♥ ♥ t♦♥ ♥ ♦♠♣t♥ ♥ T

33c

t ♦♦r♥ts ♦ ♣♦♥ts tt ♦ ♥♦t ♥ Dc r ♥♦t st♦r ♥ t tr♥t♦♥ t strtr♦r ♠♠♦r② ♥② rs♦♥s ② r tr♦ t t♦♥ t strtr♦r♥❴♠♣ tt ♦s ♥♦t ♦ ♦r ♦♥st♥t t♠ ss ♥ t♦ ♦ ♠♠♦r② ♦r ♥ ♦♠♣t♥ ♥ T

33c

♦ ♥♦t ♠r t t♦♦ ♦♥ s ♥ t t strtrrt② t ♣ tr ♦ t♠ ♥ t ♦♥❴s❴st s sr ♥ t♦♥ s t ♦r♥❴♠♣ ts t strtr ♦s ♥♦t ♦ ♦r ♦♥st♥t t♠ ss ♥ tsst♦♥ ①♠♥ t ♠♣t ♦ t ♦r♥❴♠♣ ♥ t ♦♥❴s❴st ♦♥ t t♠♦♠♣①t② ♦ t ♠♣♠♥tt♦♥

s ♦ ts t♦ t♦♥ t strtrs s ♦ ♠♦tt ② ♣rt♦♥srt♦♥s ♦r ♠♦st ♣♣t♦♥s t s♠s ♠ ♠♦r ♠♣♦rt♥t t♦ ② t♠♥ s♣ ♥t ♥ ♦♠♣t♥ ♥ T

3c rs t ♥② ♦ ♦♠♣tt♦♥ ♥ T

33c

sss ♠♣♦rt♥t ♥ ♦rr t♦ t ♦♥ ♦ O(n2) ♦♥ t ♦♠♣①t② s ♣r♦ ♥t♦♥ ♦ ♥ t♦ st♦r t ♥♦r♠t♦♥ ♦♥t♥ ♥ t ♦r♥❴♠♣ ♥t ♦♥❴s❴st rt② ♥ t tr♥t♦♥ t strtr t♦ ♦t♥ ♦♥st♥t t♠ss ♦r t ♠♠♦r② rsr ♦r t t ♠♠rs rqr t♦ st♦r ts t ♥t s ♥ rts ♦ s♦ rsr ♥ t tr♥t♦♥ s r♣rs♥t ♥ T

3c

s♥ ♥♦♥♥② r ♠♠♦r② ♦♥s♠♣t♦♥ ♦ t tr♥t♦♥ t strtrs ♥ t♦♥ t ①♣t ♦♠♣①t② ♦ t r♥♦♠③ ♦rt♠ ♦r

♦rsts ♥♣t ①♣t ♦♠♣①t② s t ①♣tt♦♥ ♦r t ♦♠♣①t②♦r ♣♦ss ♥srt♦♥ ♦rrs

t S st ♦ n rts ♥ t e ♥ m ♥♦t t ♥♠r ♦ s ♥ s ♦ t♥② tr♥t♦♥ ♥ ② S s ♦♠♣t ② ♦rt♠ t N ♥♦t t♥♠r ♦ rts ♥ M t ♥♠r ♦ s ♦ t tr♥t♦♥ ♦r rtr♦♥ ♣♣s ♦r ♦rt♠ sts t♦ t T

3c t tr♥t♦♥ ♦ n ♣♦♥ts s

Page 72: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♦♠♣①t②

st ♦♠♣t ♥ T33c t♥ N = n ♥ M = m ♥s♦♥s O(1) ⊆ O(N) ⊆ O(n) ♥

O(1) ⊆ O(M) ⊆ O(m) ♦ ss t♦ rts ♥ t ♦r♥❴♠♣ s ♥ O(log N)t ss t♦ s ♥ t ♦♥❴s❴st ♦♥ ♦ t rts ♠st ♦♥ rst s ♥ O(log N) ♥ t♥ t s♦♥ rt① ♠st sr ♦r ♥ t ♦rrs♣♦♥♥ st s ♥ O(N) s t ♦r ♦♠♣①t② ♦r ss t♦ t ♦♥❴s❴st s O(N)

♠♠ t T tr♥t♦♥ ♦ ♦♠♣t 3♠♥♦ t♦t ♦♥r② tts n rts ♥ m s ♥ t ♦♦♥ t♦ stt♠♥ts ♦

♥♠r ♦ s ♦ T s ♥ ② e := n + m

♥♠r ♦ rts s ♥♦t rr t♥ t ♥♠r ♦ s n ≤ m

Pr♦♦ t f ♥♦t t ♥♠r ♦ ts r rtrst χ ♦ ♥② 3♠♥♦t♦t ♦♥r② s ❬♥❪ ♥ s ♥ ② t ♦r♠

χ = n − e + f − m.

rtr♠♦r ♦r tr♥t♦♥ ♥♦ tt 2f = 4m ♣♣②♥ ts t♦ t ♦♦r♠ ②s 0 = n − e + 2m − m ♥ ts e = n + m ♣r♦s t rst stt♠♥t t s tr s ♥ s ♥♥t t♦ t st tr ts s♦ 3f ≥ 3eP♥ ts ♥t♦ t ♦r♠ ♦ ②s 0 = n − e + f − m ≥ n − e + e − m = n − m♥ ts n ≤ m

r♦♠ ♠♠ ♥ ♥♦♥ tr♥t♦♥ ♣r♦♣rts t♦♥ ♥♦tt

O(1) ⊆ O(n) ⊆ O(m) = O(e) ⊆ O(n2)

♥ O(N) ⊆ O(M)

♥t♥♥ ♦ t ♦♥❴s❴st ♥ t♦♥ s♦ tt t t♦t ♥♠r♦ s tt r ♥srt ♥t♦ ♥ r♠♦ r♦♠ t ♦♥❴s❴st s ♣r♦♣♦rt♦♥ t♦t s♠♣s tt r rt ♥ str♦② ② t ♦rt♠ tr t ♦♥rs♦♥ r♦♠T

33c

t♦ T3c t ♦♥❴s❴st s ♥♦t s ♥②♠♦r s♦ t ♥♠r ♦ ♥s t♦ t

♦♥❴s❴st s ♣r♦♣♦rt♦♥ t♦ N2 s ♥ ♦r ♠♣♠♥tt♦♥ ss t♦ rt①s ♥ O(N) t ♠♥t♥♥ ♦ t ♦♥❴s❴st s ♥ O(N3)

❲ ♥♦ sss t ♥t♦♥ts ♣rs♥t ♥ t♦♥

♦♥rs♦♥ r♦♠ T33c

t♦ T3c ♠♦st ①♣♥s st♣s r t ♦r trt♦♥s ♦r

M s r ♦ t♠ rqr t♦ r ♦♣② sts r♦♠ t ♦r♥❴♠♣ s ♥O(log N) ♦r ♦♠♣①t② s O(M log N)

♦♥rs♦♥ r♦♠ T3c t♦ T

33c

♥ t ♠♦st ①♣♥s st♣s r t trt♦♥s ♦r s ❯♥ ♦ ♥ s♦♠ ♦ ts trt♦♥s ♠♥ts ♥ t♦ ♥srt ♦r ♦♥ ♥t ♦ ♦r♥ ♠♣ ♦♥ s s ♥ O(log M)

♦♥strt♦♥ ♦ t ♦r♥❴♠♣ s ♥ O(N log N)t♦♥② ♥ t ♥ ♥ t♦ trt ♦r s ♥ ♦rr t♦ ♥ t s tt

r t♦♦ ♦♥ ♦r♥ t♦ ♠♠ tr r O(M) ♠♥② s ♥srt♦♥ ♦s ♥t♦ t ♦♥❴s❴st s ♥ O(N) ♥ ts t ♦r ♦♠♣①t② ♦ t ♥t♦♥r♠♥s O(MN)

Page 73: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

P♦♥t ♦t♦♥ ❲♥ ♦♠♣t♥ ♥ T33c ♦r t rts ♦ st t ♦♣②

sts ♠st ♦♠♣t O(log N) ♥ t ♦rsts O(M) s ♠st st ②s O(M log N) ❲♥ ♦♠♣t♥ ♥ T

3c t s ♦♥ ♦ O(m) ♣♣s

P♦♥t ♥srt♦♥ ❲♥ ♦♠♣t♥ ♥ T33c t sr♦t♥ tt ♥s t s ♥ ♦♥t

s t♦ st O(N) s ♥ t ♦rst s ♥ t s t♦ t t ♦♣② sts ♦r t rts♦ ♦ ts s s♦ ts ts O(N log N) t♦♥② t ♦♥❴s❴st ♠st ♣t ♦r ♣ t♦ O(N) s s♦ t ♦r ♦♥ s O(N2) ❲♥ ♦♠♣t♥ ♥ T

3c

t ♦♠♣①t② r♠♥s O(n)

❱rt① r♠♦ ♦♠♣①t② ♦ t rt① r♠♦ s ♥ O(n2) ♥ t ♦rst s❲♥ ♦♠♣t♥ ♥ T

33c

t ♦♣② sts ♦r t ♦ rts ♠st ①trt r♦♠ t♦r♥❴♠♣ s ♥ O(N log N) ♥ ♣ t♦ O(N) s ♠st r♠♦ r♦♠ t♦♥❴s❴st s ♥ O(N2) ②♥ ♥ ♦r ♦rsts ♦♠♣①t② ♦ O(N2)

rr② ♥ t♦♥ sss tt t tr♥t♦♥ rr② ♦ ❬❪ ♥ s ♦r ♣r♦ tr♥t♦♥s t♦♦ r ♥②③ t ♠♣t ♦ ♦♠♣t♥ ♥ T

33c

♦♥ t ♦♠♣①t② ♦ ♦t ♣♦♥t ♦t♦♥ ♥ ♣♦♥t ♥srt♦♥ ♥ s♥ t ♥②rr②

t α ♥♦t t rt♦ t♥ t ①♣t ♥♠r ♦ ♣♦♥ts ♥ t♦ ♥t ②rs♦r♥ t♦ ❬❪ t ①♣t ♦♠♣①t② ♦ t ♣♦♥t ♦t♦♥ ♥ s♦♠ ②r i sO(αi+1n) ♦r♥ t♦ t sss♦♥ ♦♥ t ♦♠♣①t② ♦ t ♣♦♥t ♦t♦♥ ②r i sr♣rs♥t ♥ T

33c t ①♣t ♦♠♣①t② ♦ t ♣♦♥t ♦t♦♥ O(αi+1n log N)

t ②r I t ♦r♠♦st ②r tt s r♣rs♥t ♥ T33c ♥ t t♦t ♦♠♣①t②

♦ t ♣♦♥t ♦t♦♥ s

i<I∑

i=0

αi+1n +

i=∞∑

i=I

αi+1n log N = n ·(

α(1 − αI)

1 − α+

αI+1

1 − αlog N

)∈ O(n log N)

♦t tt t ♦♥t αI+1

1−α ♦ log N t r② s♠ t r♦♥ Ir♥ ♣♦♥t ♥srt♦♥ t♦♥② t ♣ ♥ ♦♥ ♣♦♥trs ♠st st ♦r ②rs

r♣rs♥t ♥ T3c ts t♦ ♦♣rt♦♥s r ♥ O(1) ♦r ②rs r♣rs♥t ♥ T

33c t

♦♥ ♣♦♥trs ♦ t ♣r♦ ♦♣s t♦ st t♦ t rs♣t ♦r♥ rt① ♥ t②r ♦ s rqrs qr② ♣r ♣♦♥tr ♥ t ♦r♥❴♠♣ s ♥ O(log N) ♣r♦t② ♦ ♥srt♥ ♣♦♥t ♥t♦ ②r i s αi s♦ t ①♣t ♥♠r ♦ ♥srt♦♥s♣r ♣♦♥t s

∑∞i=0 αi ∈ O(1)

s s♥ ♦ ♣♦♥t ♥srt♦♥ ♥t♦ t ♣r♦ ♥② tr♥t♦♥ s ♥ O(n +N2) ⊆ O(nN) ♥srt♥ ♥t♦ t rr② ♦s ♥♦t ♥ ts s♦ t r♥♦♠③ ♦rsts ♦♠♣①t② s O(n2N)

♠♠r② ♦r ♥ ♦r ♦ t rsts ♦ ts st♦♥ N s ♦♥st♥t t s②♠♣t♦t r♥♥♥ t♠ s t s♠ s ♦r ♦♠♣t♥ ♥②

tr♥t♦♥s ♥ E3 ♥♠② ♥ t ♦rst s O(n3) ♥ ♠♣r♦ t♦ r♥♦♠③

♦rsts O(n2) ② s♥ t rr② ♥ s t ♣♦♥t st ♦s ♥♦t tr♥t♦♥t♥ N = n ♥ log n t♦r s ②s ♦rsts ♦♠♣①t② ♥ O(n3 log n)r♥♦♠③ ♦rsts O(n2 log n) ♥ s♥ t rr②

②r t t s♠st ♥① ♥ rst ♥♠r ♦ ♣♦♥ts

Page 74: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

t② ♦ ♥ tr♥t s♥

E3

T3

♦♥❴s❴st ♠♥t♥♥ O(N3)T

33c

→ T3c O(M log N)

T3c → T

33c

O(MN)P♦♥t ♦t♦♥ O(m) O(m + M log N)P♦♥t ♥srt♦♥ O(n) O(n + N2)❱rt① r♠♦ O(n2) O(n2)P♦♥t ♦t♦♥ t rr② O(n) O(n log N)

r♥t♦♥ O(n3) O(n3N) t rr② O(n2) O(n2N)

r ♦ t rsts ♦ t♦♥

t② ♦ ♥ tr♥t s♥

♥ ts t♦♥ sr ♥ ♦r ♥ tr♥t s♥ tt ♥trts t tr♥t♦♥s ♥ t ♣r♦ tr♥t♦♥s s tr♥t s♥ s♥ sr ♥ ❬❪ ♠♦tt♦♥ ♦r s ♥ ♣♣r♦ s tt t ♦rt♠s♦r ♦♠♣t♥ tr♥t♦♥s ♥ E

3 ♥ T3c r ♥♦t sst♥t② r♥t ♦ s t♦

♣t s tt ♥t♦♥s s ♣♦ss ♥ t ♦ ♦r t tr♥s ♦t tt ♠♦st ♦t ② ♦♣t♠③ ♥t♦♥s ♦ss ♥② ② ♥r③♥ t♠ s♥t② t♦ ♦r ♦r♦t s♣s

tr♥t s♥ s ♦♣ t♥ t ♦♦♥ ♣rtrts ♦ E3 ♥ T

3

♥t♦ ♦♥t

E3 rt① t ♥♥t② ♥rt ♠♥s♦♥s

T3 ♦r♥ s♣s ♦sts

♦ ♦ t tr♥t s♥ s t♦ ♠ t ♣♦ss t♦ s② ①t♥ t rr♥t♠♣♠♥tt♦♥ t♦ r♥t s♣s t t st ♣♦ss r♥♥② ♥ ♦ s ♦ t tr♥t s♥ s t♦ s♣t t ss r♥t♦♥❴ ♥t♦ tr sss rt② ♥rt♥ r ♠♥ s♣ ss ♣r♦s ♥t♦♥t② tt♣♥s ♦♥ t s♣ t s ♥♦ t♠♣t ♣r♠tr ♦ t tr♥t♦♥ t♦tr tt tr♥t♦♥ t strtr ♥ t ♦♠tr trts

r tr♥t s♥

Page 75: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

tr♥t♦♥ t strtr ♥ t ♦♠tr trts r t s♠ s sr ♥t♦♥ t s ♥♦ st t t sss ♥ ♠♦r t

♥r s s ss ♦♥t♥s t ♥t♦♥t② tt ♦s ♥tr ♣♥ ♦♥ ts♣ ♥♦r ♦♥ t tr♥t♦♥ t②♣ s r ♠♦st② r♣♣r ♥t♦♥s r♦♠ t tr♥t♦♥ t strtr ♥ ♦tr ♥r ♣r ♥t♦♥s

♠♥ s♣ s ss s ♥ ♥ t s♥ ♥ s s t♦ ♥ r②t♥tt ♣♥s ♦♥ t ♠♥ s♣ ♦ t tr♥t♦♥r s ♥t♦♥t② tt ♣♥s ♦♥ ♦t s♣ ♥ tr♥t♦♥ t②♣ ♥ ts ss s st♦rs ❬❱❪ tt ♠♦② t ♥t♦♥t② r♥t t♦ t tr♥t♦♥ t②♣♥ t s♣ ss

r♥t♦♥ ss tr♥t♦♥ ss ♣r♦s t s♠ ♥tr s ♥ t s♥ sr ♥ t♦♥ ♥♣♥♥t ♦ t ♠♥ s♣ t ♣r♦s ♥r♦rt♠s ♦r ♣♦♥t ♦t♦♥ ♣♦♥t ♥srt♦♥s ♥ ♣s s ss s ♥② s♣③ t♦♥② tr♥t♦♥ ♥ rr tr♥t♦♥

♥ rtr s♣s s qt s♠♣ t ts s♥ ♥② ♥ s♣ ss ♥ ♣♦ss② r♥t ♦♠tr trts ss s ♥ s♥ t ♦rt♠s ♣r♦ ② ttr♥t♦♥ sss r ② ♥r

rst ♦ tt ♠♥ ♥t♦♥s ♦ ♥ t s ss ♥ t rs♣ts♣ ♥ tr♥t♦♥ sss ♦♥t♥ ♦♥② st♦rs tt ♠♣♠♥t s♣ s♣ ♥tr♥t♦♥ s♣ ♥t♦♥t② ♦r ♥ ts ② ♦ ♦♥② ♠r ♦t ♦t ♦ ♥s ♦ ♦ t♦t ♦s♥ ♥② ♥② s t tr♥t♦♥sr ② ♦♣t♠③ ♥ ② s t s ♥♦t ♣t t♦ ♠♣♠♥t ♠♦t♦♥stt tr ♥rt② ♥st ♥② s ♠♥s tt ♠♦st t ♥t♦♥t② ♥s♣ ♥ t s♣ ss ♠♣s tt ♠♦st ♦ t ♦ ♣t ♥ts rsts ♣rrr ♥ ♦♠♣t② s♣rt ♠♣♠♥tt♦♥ ♦r t ♣r♦tr♥t♦♥s

①♣r♠♥ts

♥ t♦♥ ♥tr♦ tr ♠♣♠♥tt♦♥s ♦ ♦rt♠s t♦ ♦♠♣t t ♣r♦ ♥② tr♥t♦♥ ❯♥♦rt♥t② ♠♦st ♦ t♠ r tr ♥♦t ♣② ♦r ♥♦t ♠♥t♥ ♥②♠♦r ❲ ♦♠♣r ♦r ♠♣♠♥tt♦♥ ♦ t ♦rt♠ t♦♦♠♣t t ♣r♦ ♥② tr♥t♦♥ t♦ t ♠♣♠♥tt♦♥ ♦r t ♥② tr♥t♦♥ ♦ E

3 ❲ ♣rs♥t s♦♠ ①♣r♠♥ts ♦♠♣r♥ t ♦♠♣tt♦♥♦ t ♥② tr♥t♦♥s ♦ E

3 ♥ T3 ♥ ② t s♠ st ♦ ♣♦♥ts ♥ D3

c♦r ♥♦r♠② strt ♥♣t ♣♦♥ts t ♦♠♣tt♦♥ ♦ t ♣r♦ ♥② tr

♥t♦♥ s ①♣t t♦ st② s♦r t♥ t ♦♠♣tt♦♥ ♦ t ♥② tr♥t♦♥ ♦ E

3 t♦ ♦r s ② ♠♥♥ t ♦sts ♥ t ♦♠♣tt♦♥ ♥♦r♥ s♣s

t rst s♦ ①♣r♠♥ts ♦♥ t ♦♥strt♦♥ ♦ t ♥② tr♥t♦♥ s♥r♥t ♦♥rt♦♥s ♦ t ♦ sr ♦♣t♠③t♦♥s t ♦r t♦t s ♦ ts♣t s♦rt♥ ♥ t ♠♠② ♣♦♥t st ♥♦tr tst srs rstrts ♦♥ t ♣♦♥t ♥srt♦♥♥ T

3c s t ♠♦st rt ♣rt ♥ t ♥② tr♥t♦♥ ♦♥strt♦♥ ❲ ♥srt

t ♣♦♥ts ♥t♦ ♣r♦♠♣t tr♥t♦♥ ♥ T3c ♥ ts ② ♦ ♦♠♣tt♦♥ ♥

T33c

t ♥ t s ♦ t ♠♠② ♣♦♥ts ts ♣♦♥ts r ♦s♥ t r♥♦♠ ♥ ♦♥♦t r♠♦ t♠ ♥ ♥ r② ♣rs♥t rsts ♦ t s♠ ①♣r♠♥ts s♥ t

Page 76: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

①♣r♠♥ts

tr♥t♦♥ rr② s ♣♦♥t♦t♦♥ tstrtr ♦♦♥ ①♣r♠♥t tstst rt① r♠♦ ♥t♦♥t② ♥ r♥ t ♥② tr♥t♦♥ ♦♥strt♦♥tsts ♥ t ♣♦♥t ♥srt♦♥ tsts s♥ ♦♠tr trts ss tt s s♣③ t♦ ts tt Dc s t ♥t ♥ ♥② ♦♠♣r t t♦ rtr ♦ t♦♥ s ♦ t ♦♣t♠③t♦♥s s s r♥t ♣r♦♣rts ts ①♣r♠♥ts ♣ t♦♥t② s♣ ♥ts ♥ s♦rt♦♠♥s ♥ ♦r ♠♣♠♥tt♦♥

♥♣t ♣♦♥t sts

❲ r♥ ①♣r♠♥ts ♦♥ ♦t ♥rt t ♥ r t r♦♠ str♦♥♦♠② ② ♦rts②♦ Pr♦ ♥ ♥ ❲rt ♥ ♥♠rs t ♦r♥ ♦♠♥ s t ♦♣♥♥t [0, 1)3

❲ ♥♦t t t sts s ♦♦s

♣♦♥ts ♥♦r♠② strt ♥ t ♦♣♥ ♥t

s♣ ♣♦♥ts ♥♦r♠② strt ♦♥ s♣r ♦ rs 0.5 ♥tr t (0.5, 0.5, 0.5)

str ♥♣t t r♦♠ rsr ♦♥ str♦♥♦♠②

❲ ♥♦ sss t r♥t ①♣r♠♥ts ♥ t r♦s ♦ t ts tr♥♥♥ t♠s ♦r ♥♣t ♣♦♥t sts t ♥♠r ♦ ♥♣t ♣♦♥ts ♥ ♥ t rst ♦♠♥ r♥♥♥ t♠ ♦r ♦ ♥② tr♥t♦♥ ♦♠♣tt♦♥ ♦ E

3 ♥ T3c s s♦♥

♥ t s♦♥ ♥ tr ♦♠♥ rs♣t② rtr♠♦r ♥ t st ♦♠♥ t t♦r ② t ♦♠♣tt♦♥ ♦ t ♥② tr♥t♦♥ ♦ T

3c s s♦r s ♥ r♥♥♥

t♠s r ♥ ♥ s♦♥s ①♣r♠♥ts r r♥ ♦♥ ♥ ♥t ❳♦♥ ♦r t ③r♥♥♥ ♦r ♥ ❲ ♦rt tsts tt t♦♦ ♦♥r t♥ s♦♥s♦rt tsts r ♠r s ♥ t ts

♦♥strt♦♥ ♦ t ♥② tr♥t♦♥

❲ r♥ tr srs ♦ ①♣r♠♥ts ♥ t t t ♦♥rt♦♥ ♦♥ s♥ ts♣t s♦rt♥ ♥ ♦♥ s♥ ♦t s♣t s♦rt♥ ♥ t ♠♠② ♣♦♥t st

♦r ①♣r♠♥t st t t ♦r t ♣♦♥t sts str ♥ s♣ s s ♣♦t ♦ ts t ♦t tt t ♣♦t ①s r ♦t s ♦rt♠②

t ♦♥rt♦♥

E3

T3c t♦r

102

103

104

105

106

str E3

T3c t♦r

1 · 103

1 · 104

1 · 105

2 · 105

5 · 105

1 · 106

2 · 106

♣t②♥ ♥sttt r♦♥♥♥ tr♥s

Page 77: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

s♣ E3

T3c t♦r

102

103

104

105

106

107

♥ ts ①♣r♠♥t s tt ♦r t ♣♦♥t st ♦ 102 ♣♦♥ts t s♦♦♥ t♦ t ♦r ♦ ♦♠♣t♥ ♥ T

33c

s qt r ♦r rr ♣♦♥t sts t s♦♦♥♦♠s s♠r s t ♥t ♦♠♣tt♦♥ ♥ T

33c

s ss ♠♣t ♦♥ t ♦rr♥♥♥ t♠ ♥② ♦r ♣♦♥t sts ♦ ♦t 106 ♣♦♥ts t ♦♠♣tt♦♥ ♦ ♣r♦tr♥t♦♥s ts ♦t t s♠ t♠ s t tr♥t♦♥ ♦ ♣♦♥t sts ♥ E

3 s♦♦♥ ♦♠s ♥

①♣r♠♥ts str s♦ tt t r♦r ♣♦♥t st s s♥t② strtt♦ ♦r s♠r t♦

♦r t s♣ ①♣r♠♥t t r s♦♦♥ ♣rssts ♥ ♥ r♦s r t ♣r♦♥② tr♥t♦♥ s ♥r r♣rs♥t ♥ T

33c

s ♦r ts ♣♦♥t st tr r②s s ♦♥r t♥ t trs♦ ♦ rtr♦♥ s t ♣r♦t♦♥ ♦ t st♦♥ ♦ t ♣r♦ ♥② tr♥t♦♥ ♦ t s♣r ♦♥t♦ T

3c s ♥ ♠♦st ss

②s ♦ ♥t ♥♥♦t ♥ ♦♣ t♦ ♦ ♠ ttr ♦r♦r r ♥♦t r♦ ♥② s ♥ r♦r ♣♣t♦♥s r s stt♦♥ ♦ ♦r r♦♥s♦♦♥ ♦r rr ♣♦♥t sts s t♦ ♥♥ t tr♥t♦♥ ♦ t ♦r♥ s♣r sr st♠♣s ♥ t♦♥ ♥t♦♥ s r ♥♦ s s t ♣r t♦ ♣② ♥ ♦rr t♦ ♦ s ♠ ♦r s ♣♦ss ♥ ♦♠♣t♥ ♥ T

3c

s r② t ♣r♥♣ ♦

❲t s♣t s♦rt♥

E3

T3c t♦r

102

103

104

105

106

107

str E3

T3c t♦r

1 · 103

1 · 104

1 · 105

2 · 105

5 · 105

1 · 106

2 · 106

Page 78: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

①♣r♠♥ts

s♣ E3

T3c t♦r

102

103

104

105

106

107

❲♥ s♥ t s♣t s♦rt♥ t ♦r ♦ t r♥♥♥ t♠s ♦♠s ♠♦st♥r ♥ t ♥♠r ♦ ♣♦♥ts ♣r♥♣ ♥ ♦♠s r♦♠ t t tt t ♣♦♥t♦t♦♥ st♣ ts rt ♦♥sr② ♣♦♥t ♦t♦♥ ♥t♦♥ s r② s♠rr♥♥♥ t♠s tr ♦♠♣t♥ ♥ E

3 ♦r T3c ♦ ♥ t tsts ♦ t t ♦♥rt♦♥

t ♣♦♥t ♦t♦♥ s ♥ tt♥t♥ t ♦♥ t ♦r r♥♥♥ t♠ r♥ ♥t s ♦ s♥ s♣t s♦rt♥ ♦♠♣t♥ ♣r♦ tr♥t♦♥ ♦ r ♥♠r ♦strt ♣♦♥ts s ♦t t♠s s♦r t♥ ♦♠♣t♥ tr♥t♦♥ ♦ E

3 rsts ♦ t str ①♣r♠♥t ♥ r t t ①♣r♠♥t s♣t s♦rt♥ ♦s ♥♦t ♦r r② ♥t② ♦♥ t st ♦ ♣♦♥ts ♦♥ s♣r ♥

t ♣r♦ s ts t s ♦t ② t ①♣♥s ♥♥ ♦ t ♦r♥ s♣

❲t ♠♠② ♣♦♥t st ♥ t s♣t s♦rt♥

E3

T3c t♦r

102

103

104

105

106

str E3

T3c t♦r

1 · 103

1 · 104

1 · 105

2 · 105

5 · 105

1 · 106

2 · 106

s♣ E3

T3c t♦r

102

103

104

105

106

Page 79: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

♦r t ①♣r♠♥t t s♦♦♥ ♦r t st ♦ 102 ♣♦♥ts s ①♣♥ ②t t tt ts ♣♦♥t st ♦s ♥♦t ♥ ♥② tr♥t♦♥ ♦ T

3c ♥ ts t

♦rt♠ ♠st st t♦ ♦♠♣t♥ ♥ T33c

r♠♦♥ t ♠♠② ♣♦♥ts ♦r rr♣♦♥t sts ♥♦ ♦♠♣tt♦♥ ♥ T

33c

s rqr t ♥ s♦ t s♦♦♥ s ♠ ss t♦r s t♥ ♥ ♦t tt t rr t ♣♦♥t st t ss s ts♦♦♥ ♥ ①♣♥ ♥ t ♦♦♥ ② ♥ ♦r ♠♣♠♥tt♦♥ ♣r♦s♣③ ♥t♦♥s ♦r ♥ ♠♦r ♥t② t s tt ③r♦ ♦sts ♣rt♦ t s♦♦♥ ♥ T

3c s t♦ ♦st ♠♥♣t♦♥s r♥ t ♣♦♥t ♥srt♦♥ ♥ s

t ♥♦♥③r♦ ♦sts r ♥♦ s t ♣♦♥t st s ♥♦r♠② strt t ♣r♥t♦ s t ♥♦♥③r♦ ♦sts t ♥♠r ♦ s tt r ♦t ♦♥ t ♦♥r② ♦t ♦r♥ ♦♠♥ s s♠r ♦r r ♣♦♥t sts t♥ ♦r s♠ ♣♦♥t sts s♦ t rts♦♦♥ rss ♥ t ♥♠r ♦ ♣♦♥ts r♦s

♦r t s♣ ①♣r♠♥t t 104 ♣♦♥ts t s♦♦♥ s ss t♥ ♦r t s s ts ♣♣r♦ ♦s ♥srt♥ ♣♦♥ts ♥ T

33c ♥② t ♣♦st♣r♦ss♥ ♦ r♠♦♥

t ♠♠② ♣♦♥ts ♥ ♦♥rt♥ t tr♥t♦♥ t♦ T33c

s ①♣♥s s rst ssts tt ♦r ♣♦♥t sts ♦ ♠♦r t♥ ♦t ♣♦♥ts tt ♦ ♥♦t ♥ tr♥t♦♥♥ T

3c t s s t♦ s t ♠♠② ♣♦♥t st

P♦♥t ♥srt♦♥ ♥ T3c

r strt t ♣r♦♠♣t tr♥t♦♥ ♦ T3c r♦♠ 1000 ♥♦r♠② strt

♥♣t ♣♦♥ts ♥ ♥srt ♠♦r ♣♦♥ts ❲ ♦ ts t ♥ t♦t s♣t s♦rt♥ ♦ t♥♣t ♣♦♥ts ♦ ♦ ts ①♣r♠♥ts s t♦ ♦♠♣r t ♥srt♦♥ ♦ ♣♦♥ts ♥ T

3c

♦♥② t♦ tr ♦t ♣♦t♥t ♦r ♦r ♠♥♥ ♦♣s ♦r t ♠♠② ♣♦♥t st

❲t♦t s♣t s♦rt♥

E3

T3c t♦r

102

103

104

105

106

str E3

T3c t♦r

1 · 103

1 · 104

1 · 105

2 · 105

5 · 105

1 · 106

2 · 106

s♣ E3

T3c t♦r

102

103

104

105

106

Page 80: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

①♣r♠♥ts

r s ♥ ♠♦r r② ♥ tr ①♣r♠♥ts tt t r t ♥♠r♦ ♣♦♥ts t ss s t s♦♦♥ ♦t tt s♦ t s ♦ ♣♦♥ts ♦♥ s♣r ♥♥♦ ♦♠♣t s② t s s tr r t♦♥ ♣♦♥ts ♥sr♥ tt ♦♠♣tt♦♥s ♥ ♦♥ ♥ T

3c rtr t♥ T

33c s t♦♥ ♣♦♥ts r ♦♥t♥

♥ t ♥ rst t♦

❲t s♣t s♦rt♥

E3

T3c t♦r

102

103

104

105

106

107

str E3

T3c t♦r

1 · 103

1 · 104

1 · 105

2 · 105

5 · 105

1 · 106

2 · 106

s♣ E3

T3c t♦r

102

103

104

105

106

107

s ①♣r♠♥t ♦♥r♠s t ♦ ①♣♥t♦♥s t♦t ♥ ♥ rsts

tr♥t♦♥ rr②

❲ r♥ t s♠ ①♣r♠♥ts s ♦ s♥ t tr♥t♦♥ rr② ♥ t ♣r♦ s t rr② srs r♦♠ t t tt tr r ②s ②rs r♣rs♥t♥ tr♥t♦♥ ♦ T

33c ❲ ♦♥② s♠♣ ♦ t rsts ♦r t ♣♦♥t st ♦ 106

♣♦♥ts

Page 81: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

E3

T3c t♦r

t s♣t s♦rt♥ ♠♠② ♣♦♥t st s♣t s♦rt♥ ♣♦♥t ♥srt♦♥ ♥ T

3c

♣♦♥t ♥srt♦♥ ♥ T3c s♣t s♦rt♥

♥ ♣rt ♦♥② t tr♥t♦♥ ♦ t ♣♣r♠♦st s r♣rs♥t ♥ T33c s♦ t

s♦♦♥ s t t♦r t♥ ♥ ♦♠♣rt② s♠ t tt ts♦♦♥ s s♠r ♦r ①♣r♠♥ts s♦s tt ♥ T

3c t tr♥t♦♥ rr②

s♦s s♠r ♦r s ♥ E3

❱rt① r♠♦

r r♠♦ rts r♦♠ tr♥t♦♥ ♦ t ♥ s③

E3

T3c t♦r

104

105

106

str E3

T3c t♦r

1 · 104

1 · 105

2 · 105

5 · 105

1 · 106

2 · 106

❲ s tt t r♥♥♥ t♠ ♦ r♠♦♥ rts ♦s ♥♦t ♠ ♣♥ ♦♥t s③ ♦ t tr♥t♦♥ ♦r ♦r t ♣r♦ tr♥t♦♥ s ♦♠♣rt②s♠ t ss s♦♦♥ ♦ t♦r t♥ ♥ ♥② t tr♥t♦♥♠st ♦♥rt t♦ T

33c

r♥ t r♠♦ t s♦♦♥ t♦r ♦s ♣ t♦ ♦t

♣ ♦r♥ ♦♠♥

♥ t ♣r♦ tr♥t♦♥s t ♦r♥ ♦♠♥ ♦ t ♣r♦ s♣ ♥ ♦s♥ ② t sr ❲♥ ♦♠♣t♥ ♣rts ♦ ♣♦♥t♦st ♣rs ♣♦♥ts ♠st tr♥st ② ♠t♣s ♦ t ♥t ♦ t ♦r♥ ♦♠♥ s s ♥♠r② ♠♦r♥♦ t♥ s♠♣② ①♥ t ♦r♥ ♦♠♥ t♦ t ♥t

❲ ♦ rt s♣ trts ss tt ♣r♠ts ♦♥② t ♥t s ♦r♥ ♦♠♥ ①♣r♠♥ts ♦ s♦ tt ♥ ts s ♥ ♦t ♦♥ t r♥♥♥ t♠ ♦r♦t 106 ♥♦r♠② strt ♣♦♥ts ♥ t ♥ t ♦s♠♦♦ t st ♦ 106

♣♦♥ts

T3c T

3c, c = [0, 1)3 ♣♣ ♥

st♥r

s♣t

♠♠② s♣t

♥s T3c

♥s T3c s♣t

Page 82: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

①♣r♠♥ts

str T3c T

3c, c = [0, 1]3 ♣♣ ♥

st♥r

s♣t

♠♠② s♣t

♥s T3c

♥s T3c s♣t

❲ s tt t s♣♣ s r ♥ t ss ♥ s♣t s♦rt♥ s s s♥ ①♣♥ ② t t tt ♦r s♣③t♦♥ t♦ c = [0, 1)3 rts t ♣rtt♦♥ ♥ t ♣rt ♦ t r♥♥♥ t♠ s ♣ ♥ ♣rt t♦♥ s r ♥s♥ s♣t s♦rt♥ ❲ tt t rst♥ s♣♣ s ♥♦t s♥t t♦ ♥ts tr ♥ t ♣ rs

♦♠♣rs♦♥ ♦ t rtr ♦ t♦♥

♥ t ①♣r♠♥ts ♦ s♥ tt tr ♦♠♣t♥ ♥ T3c ♦r T

33c

s ♠♣t ♦♥ t r♥♥♥ t♠s r tst ♦r ♥ ♣♦♥t sts tr ♥srt♦♥ ♦ ♦ ♠♥②♣♦♥ts t tr♥t♦♥ s s♦♠ ♦ t ♦♥t♦♥s ♣rs♥t ♥ ♣tr ❲ s t♦♦♥ ♥♦tt♦♥ ♦r t r♥t ♦♥t♦♥s

② s s t ♥♠r ♦ ♣♦♥ts ♦r t ♣♦♥t st ♥s tr♥t♦♥♦ T

3c ♦r t rst t♠ ♥ssr② ♥ s♥t ♦♥t♦♥ ♦ ♦r♠ s

s t♦ ♦♠♣t ts ♣r♦♣rt② ♦t tt ② ♥ rtr ♣♦♥ts t ♣♦♥t st ♥♦s ts ♣r♦♣rt② ♥

♠tr s s t ♥♠r ♦ ♣♦♥ts ♦r t ♣♦♥t st s t♦♥t♦♥ ♦ rtr♦♥ ♦r t rst t♠ t s ♥ tr♥t♦♥ ♦ ts ♣♦♥tst t ♠tr ♦ t rst r♠sr♥ s s♠r t♥ t ♥t♦ t ♦r♥ ♦♠♥

♥t s s t ♥♠r ♦ ♣♦♥ts ♦r t ♣♦♥t st s t ♦♥t♦♥ ♦ rtr♦♥ t ♥t rtr♦♥

❲ r♥ t tsts ♦♥ t ♣♦♥t sts ♥ str ♦r t ♣♦♥t st s♣ ♦r ♥st♥ts rtr r ♥r ❲ r♥ ①♣r♠♥t t ♥ ♦♥ r♥♦♠ ♥srt♦♥♦rr ♥ ♦♥ s♥ s♣t s♦rt♥ s sr ♥ t♦♥

rsts t♦t t s ♦ s♣t s♦rt♥ r s♦♥ ♥ t t♦ ♦♦♥ ts

102

103

104

105

106

107

str 1 · 103

1 · 104

1 · 105

2 · 105

5 · 105

1 · 106

2 · 106

♥ t t♦ ♦♦♥ ts t rst t t s ♦ s♣t s♦rt♥ r ♥

Page 83: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

102

103

104

105

106

107

str 1 · 103

1 · 104

1 · 105

2 · 105

5 · 105

1 · 106

2 · 106

t ♣♦t s♦s t ①♣r♠♥ts t♦t s♣t s♦rt♥ t rt ♣♦t s♦s t①♣r♠♥ts t s♣t s♦rt♥

tsts r r♥ t♠s ♥ t ♣rs♥t ♥♠rs r t rt♠t ♠♥s ♦ rsts s s ♦♥ s t rsts ♦ ♦♥ r♥ ♥ r② t♦ t r♥♦♠③t♦♥♥ t ♦rt♠

s ♦r♠ s ♥ssr② ♥ s♥t ♦♥t♦♥ ♦♥ tr t ♣♦♥t st♥s ♥② tr♥t♦♥ ♦ T

3c t ♥♠rs ♥ ♦♠♥ ♥ ♦♥sr s t

st ♣♦ss rst ♦t tt t ♦♥t♦♥ ♦ ♦r♠ s ♥♦t s♥t ♦r ♦r t♣r♣♦s s t♦ tr ♥② s♣rst ♦ t ♣♦♥t st s tr♥t♦♥ ♥T

3c ❲ ♥ ♦♥sr t rsts ♦ ♦♠♥ s ♦r ♦♥s ♦♥ t ♠♥♠♠ ♥♠r ♦

♣♦♥ts rqr t♦ st t♦ T3c ♥ s t t♦ ♠sr t qt② ♦ ♦r ♦♠tr rtr

s ♦ s♣t s♦rt♥ ♥rss t rqr ♥♠r ♦ ♣♦♥ts t s s♥♦ t ♣♦♥ts r ♥srt ♥ s♣ ♦rr ts t ts ♦♥r ♥t t ♣♦♥t st ss♥t② strt ♥st rsts ♦r t ♣♦♥t st str s♦ tt t♥♠r ♦ rqr ♣♦♥ts s r② s♥st t♦ t ♥♣t ♣♦♥t st

ts s♦ tt ♥r② ♣♦♥t sts ♦ ♦t r♥♦♠ ♣♦♥ts r② ♥ ♥② tr♥t♦♥ ♦ T

3c ♦r t ♥ ♣♣♥ tt ♥srt♥ ♣♦♥t ♥ s

tr♥t♦♥ s t♦ ♣♦♥t st tt ♦s ♥♦t ♥ ♥② tr♥t♦♥ ♦ T3c

♥②♠♦r ♥ ♥r ♦t ♣♦♥ts r ♥ssr② ♦r t rst ♠♣t② ♠tr t♦ s♠r t♥ ♥ ♥t ♦ t ♦r♥ ♦♠♥ ♦r♥ t♦ rtr♦♥ s ♣♦♥t sts ♥ ♥② tr♥t♦♥ ♦ T

3c ♥ rtr ♣♦♥ts ♦

r ♦♠♣t♥ t r♠♥tr ♦ ttrr♦♥ s ♠♦r ①♣♥s t♥ ♦♠♣t♥ tst♥ ♦ t♦ ♣♦♥ts t s ② ♦rt♠ tsts ♦r t ♦♥st ♥t t♦ s♠r t♥ 1√

6c s rtr♦♥ s ts s str♦♥r rtr♦♥ ♦t t♦

♣♦♥ts r rqr ♦r t ♦rt♠ t♦ st t♦ ♦♠♣t♥ ♥ t st ♦r♥s♣ ❲♥ t t st ♦♠s r ts ♥♠r ♥ ♦♥sr ♥

Page 84: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣♣t♦♥s

♣♣t♦♥s

t♦ t ♠♦rt② ♦ t s s② ♣♦ss t♦ ♣ r♥t ♥t♦♥ts t♦tr ♦r ♥st♥ tr r sr ♦rt♠s tt s tr♥t♦♥s t ♣s♣ ♦♠♣tt♦♥ ❬❨❪ ♦r t ♠s♥ ♦rt♠s ❬❨ ❨❪

♦r t ♥tr ♦ t ♠♣♠♥tt♦♥ ♦ ♣r♦ tr♥t♦♥s s s♦♠♠t♠t② ♠♦tt r♥s t♦ t ♥tr ♦ t ♥♦♥♣r♦ tr♥t♦♥ss ♥ t♦ ♥tr♦ ♣trs t♦ ♠ t ♣r♦ tr♥t♦♥s ♦♠♣t t♦♦tr ♦rt♠s

Pr♦ ♣ s♣s

♣ s♣s ♥ sr ♥ ❬ ❪ s ①t♥s♦♥ s ♥ ♠♦tt ②t ♥ ♦ str♦♥♦♠rs ♦r ♦♠♣t♥ ♣r♦ ♣ s♣s ♦ s♠t♦♥s ♦♥ t ♦s♠ ❬❲❱P+❪ s ♦♥ t ♦s♠♦♦ ♣r♥♣ t♦♥ ts s♠t♦♥s rr♥ ♦♥ ♦♠♣rt② s♠ s♠♣ ♦ t ♦s♠ ♦r t ♦♥rs ♦ ts♠♣ ♥ sst♥t t ♦♥ t t♦♣♦♦② ♦ ts ♣ s♣s ② ♦♠♣t♥♣r♦ ♣ s♣s ts ts ♥ ♦

♥t♦♥ ❬❪ ♥ ♣♦♥t st S ♥ ♣r♠tr α t 0 < α < ∞ t♣ s♣ ♦ S s t sst ♦ s♠♣s ♦ DT (S) tt r♠sr♥ ♦rs α ♦r s♠r tt ♦s ♥♦t ♥② ♣♦♥t ♦ S ♥ ts ♥tr♦r

r♣ t ♥② tr♥t♦♥ ② t ♥② tr♥t♦♥ t♥ t t ♣ s♣s ♥t♦♥ rt② ①t♥s t♦ ♣r♦ tr♥t♦♥s

♠♣♠♥tt♦♥ ♦ ♣ s♣s ts ♥ ♠♣♠♥tt♦♥ ♦ tr♥t♦♥♦rt♠ s t♠♣t ♣r♠tr r♥ t ♦♥strt♦♥ ♦ t ♣ s♣ rst t t ♥② tr♥t♦♥ s ♦♠♣t ♥ t♥ t ♣ s♣ ♦♥ t♦♣ ♦ tt tts t♦ s♠♣① t s♠st α ♦r t ♣♣rs ♥ t ♣ s♣ ♥♣r♦s trt♦rs t♦ ♦t♣t ♣ s♣s ♦r ♥ α

r② s♠ ♣♣r♦ ♦rs ♦r ♣r♦ tr♥t♦♥s ♣r♦tr♥t♦♥ ♠♣♠♥tt♦♥ ♦t♣ts tr♥t♦♥ ♦♥ t♦♣ ♦ t ♣ s♣♥ ♦♠♣t ♥ ♦rr t♦ ♦ s♦ t ss ♣❴s♣❴ ♠st ♥st♥tt tt ss Pr♦❴❴♥②❴tr♥t♦♥❴ s t♠♣t ♣r♠tr t s♦♠ts rs ♥ t ♠♣♠♥tt♦♥ tt r s♦ s ♦♦s ♦t tt ♣r♦t ♣ s♣s r ♥♦t ②t s tr s ♥♦ ♠♣♠♥tt♦♥ ♦ t♣r♦ ♥② tr♥t♦♥s ②t

♥ ♦rr t♦ sts ♦♠♣tt② t♥ t ♣ s♣ ♠♣♠♥tt♦♥ ♥t ♣r♦ tr♥t♦♥s t♦ r♥ s♦♠ t②♣s ♥ ♥t♦♥s tt①st ♥ t tr♥t♦♥s t ♥♦t ♥ t ♣r♦ tr♥t♦♥ss r ♠♥② ♥t♦♥s ♥ t t rt① t ♥♥t② ♥ ♥rt ♠♥s♦♥s♥ tr♥ ♦t t♦ tr ♦r t ♣r♦ s

• ②♣ ♥t❴❬s♠♣①❪❴trt♦r ♥ t ♣r♦ tr♥t♦♥ s♠♣s r♥t ts ts t②♣ ♥ ♥ t♦ t s♠ s t ❬♠♣①❪❴trt♦r

• ♥t♦♥ ♠♥s♦♥ ♥ t ♣r♦ tr♥t♦♥ r ②s ♦♠♣t♥ ♥ tr♠♥s♦♥s s ts ♥t♦♥ rtr♥s ②s

Page 85: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

• ♥t♦♥ s❴♥♥t ♦r ♥ s♠♣① tr t s t rt① t♥♥t② s rt① s tr s ♥♦ rt① t ♥♥t② ♥ ♣r♦ tr♥t♦♥ ts♥t♦♥ ②s rtr♥s s

• ♥t♦♥ ♥♠r❴♦❴♥t❴❬s♠♣s❪ r r ♥♦ ♥♥t s♠♣s ♥ t ♣r♦ tr♥t♦♥ s♦ ts ♥t♦♥ st rtr♥s t ♦t♣t ♦ ♥♠r❴♦❴❬s♠♣s❪

rtr♠♦r s sr ♥ t♦♥ ♥♥♦t rt② ss ♣♦♥t ♦♦r♥ts♦ rts tr♦ t tr♥t♦♥ t strtr ♦ ♥ t ♣ s♣ ♠♣♠♥tt♦♥r② ♣♦♥t ♦♦r♥t ss ♦ t ♦r♠ rt①♣♦♥t s t♦ r♣② ♥ ①♣rss♦♥ ♦ t ♦r♠ ts♣♦♥t t♦♥

♥ t ♣r♦ ♣ s♣s r t s ♥trst♥ t♦ ♦♠♣t tr tt♥♠rs s ♥ ♦♠♣s s♥ t ♦rt♠ ♦ ❬❪ ♥ t ♦r ♦ ❬s❪r s♦s sr♥s♦t ♦ ♣r♦t♦t②♣ ♠♣♠♥tt♦♥

r r♥s♦t ♦ ♠♦ ♣r♦t♦t②♣ ♦r ♦♠♣t♥ ♣r♦ ♣ s♣s ♥ trtt ♥♠rs

Pr♦ sr ♠sr

rsts ♦ ts st♦♥ r ♦♥t ♦r t ❱ssr♦♥ s♦♣♦♦s ❬❪ sr ♠sr ♣r♦s ♥rt♦♥ ♦ tr♥r ♠ss t♦ ♣♣r♦①♠t

s♠♦♦t srs t ♠♣♠♥ts t ♠s♥ ♦rt♠ sr ♥ ❬❪ ♦r sr♠s ♦♠♣t ② s r

♦rt♠ ♦rs s ♦♦s t ♠♥t♥s ♥② tr♥t♦♥ ♥ q ♦s♦ sr ts t s sr t ts ❱♦r♦♥♦ ♥trsts tsr r s st ♦ s♦ r♥♠♥t rtr tt tr t s ♦♦♦r ♦rt♠ t♥ strts t ♥② tr♥t♦♥ ♦ E

3 ♥ ② st ♦♥t ♣♦♥ts ♦♥ t sr t ♠♥t♥s q ♦ sr ts ♥ ♥ st♣ ♥ ♣♦♥t ♦♥ t sr s t♦ r♥ t rr♥t t sr ♥② ♦ sr t s r♠sr♥ ♦ ts t tt s ♥tr t t ♥trst♦♥♦ t sr ts ❱♦r♦♥♦ t t sr s r ♥ ② ♦♥ t sr ts r♦♠ t q r r♥ tt s t ♥tr ♦ tr sr ♥② s ♥srt ♥t♦ t ♥② tr♥t♦♥ ♥ t ♥ sr ts r t♦ t q

♠♣♠♥tt♦♥ ♦ ts ♦rt♠ ♥ s sr ♥ ❬❨❪ t ♣r♦s t♦♦♥ tr r♥♠♥t rtr s t

Page 86: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣♣t♦♥s

r sr ♠s ♦♠♣t ② ♠♦ ② ❱s ♦♠♣t♥ Pst②

• s♣t rtr♦♥ sr t s ♦♦ ts ♠♥♠♠ ♥ s rr t♥ s♦♠sr♥ trs♦

• ❯♥♦r♠ s③ rtr♦♥ sr t s ♦♦ t rs ♦ ts sr ♥② s s♠r t♥ s♦♠ sr♥ trs♦

• rtr rtr♦♥ sr t s ♦♦ t st♥ ♦ ts r♠♥tr t♦ t♥tr ♦ t r ♥② s s♠r t♥ s♦♠ sr♥ trs♦

t s ♦r t trs♦s r ♣r♦

r sr ♥② ♦ sr t

t rtr ♥ r♣ ② t srs ♦♥ rtr ♥ ♥ t♦t s t♠♣t ♥ t s♠ ② t ♥r②♥ ♥② tr♥t♦♥ ♠♣♠♥tt♦♥♥ ①♥

♥ ♦rr t♦ ♦♠♣t ♣r♦ sr ♠ss ♣ t ♣r♦ ♥② tr♥t♦♥s ♥ t sr ♠sr ❲♥ ♦♥ s♦ s♠r ♥tr ♣r♦♠s ♦rs ♦r t ♣r♦ ♣ s♣s s t♦♥ ♦st ♦ t♠ ♥ rs♦ ♥ ts♠ ② ♣r♦♠ ♣♣rs s ♥st ♦ s♥ t ♣♦♥t ♥srt♦♥ ♠t♦ ♦t ♣r♦ ♥② tr♥t♦♥ t sr ♠sr rst ♦♠♣ts t s ♥ ♦♥tt ts ♣♦♥t s♥ t ♠t♦ ♥❴♦♥ts ♥ t r♠♦s ts s ♥ s♥ s s♥ t ♠t♦ ♥srt❴♥❴♦ s sr ♥ t♦♥ ♥ ♦♠♣t♥ ♣r♦ tr♥t♦♥s t ♦sts ♦ t rts ②♥ ♦♥ t ♦♥r② ♦ t ♦

Page 87: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

t rs♣t t♦ t ♥ ♣♦♥t ♠st st♦r s ♥♦r♠t♦♥ s rt② st♦r ♥ trts ♥ ♠st ♥ ♣ tr r♥ ♦ ♥❴♦♥ts ♥ ♦rr t♦ ♥♦t ss ts tr ♦♥ s ♥♣ s ♦♥ ② ♥srt❴♥❴♦ s ♥ ♦♠♣t♥ ♣r♦ ♥② tr♥t♦♥ ♦r t♦ ♥❴♦♥ts tr ♠st ♦rrs♣♦♥♥ t♦ ♥srt❴♥❴♦ ♥ tr ♠st ♥♦t ♥② s t♦ ♥❴♦♥ts ♥t♥ sr ♠sr ♦r ♦s ♥♦t ②s ♥srt❴♥❴♦ tr ♦ ♥❴♦♥ts ♦ s ♠♦ rs♦♥ ♦ ♥❴♦♥ts tt ♥s ♣ trt① ♦st ♦r strt♥ t♦ tt s ♥ ♦♥t

♥② t t♦♥ ♦ t r♥♠♥t rtr rqr ♦♠tr ♦♠♣tt♦♥s ♦ tr♥♠♥t rtr ♠st ♣t ♥ ♦rr t♦ trt t ♦sts ♦rrt② ② r ♠ t♦ t ♦rt♠ tr♦ t♠♣t r♠♥ts s♦ t② ♥ r♣ s② ❲rt ♥ st ♦ r♥♠♥t rtr♦♥ sss ♦r t ♣r♦ s ♦t tt ♥ ♦rr t♦♦rrt② ♦♠♣t tr♥st ♣♦♥ts r♦♠ ♣♦♥t♦st ♣rs t r♥♠♥t rtr♦♥ sss♠st ss t♦ t ♥t ♦ t ♦r♥ ♦♠♥ ♦ t ♣r♦ tr♥t♦♥s ♣♦♥tr t♦ t ♣r♦ tr♥t♦♥ ♠st ♣r♦ t♦ t ♦♥strt♦r ♦ trtr♦♥ sss ♦♦♥ ♠♦t♦♥s ♠st ♠♣♠♥t ♦r t s♣ rtr

s♣t rtr♦♥

❯s t ♦sts t♦ ♦rrt② ♠ t ♥ t ♥t♦ R3 ♥ ♦rr t♦ ♦♠♣t ts ♠♥♠♠

♥ s r

r strt♦♥ ♣r♦ s♣t rt♦ rtr♦♥

❯♥♦r♠ s③ rtr♦♥

s rtr♦♥ s ♠♦r ♦♠♣t s t♦ ♦♠♣t t ♥tr ♦ t sr♥② ♦ ♥ t t s ♥♦t ♣♦ss t♦ ♥r t ♦st ♦ t ♥tr ♦ tsr ♥② r♦♠ t ♦sts st♦r ♥ t tr♥t♦♥ s ♥ s♥ ② s♠r ①♠♣ s ♥ r ♦♥ ♣ ♦r r♠sr♥ s ♦ s ❲ srt ♦st o tt ♠♥♠③s t st♥ t♥ ♦♥ rt① ♦ t t ♥ t ♦♠♣t♥tr t ♦st o ♦rrt♥ss ♦ ts ♣♣r♦ ♦♦s r♦♠ t t tt r♦♠♣t♥ tr♥t♦♥ s♥ ♦rt♠ ♥♦ tt t st ♠♣t② s ♠tr s♠r t♥ t ♦♠♥ ♥t ♦ ♦♥ ♦ t ♣r♦ ♦♣s ♦ t♥tr s ♦sr t♦ t t rts t♥ t ♦♠♥ ♥t ♥ t ♦trs rrtr ♥ tr♠s ♦ ♣rts ts ♣♣r♦ rqrs sr ♦♠♣rs♦♥s r ♦r ♥ strt♦♥ ♦ t ♣r♦ rs♦♥ ♦ ts rtr♦♥

rtr rtr♦♥

r t s♠ ♣r♦♠ s ♦r t ♥♦r♠ s③ rtr♦♥ ❲ ♥ ♣♣② t s♠

Page 88: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣♣t♦♥s

r strt♦♥ ♣r♦ ♥♦r♠ s③ rtr♦♥

s♦t♦♥ s s r

r strt♦♥ ♣r♦ rtr rtr♦♥

♥ r s♦ s♦♠ ♣r♦ ♠ss ♦♠♣t t t sr ♠srs♥ t ♣r♦ ♥② tr♥t♦♥s rs s♦ t ♦♣s ♦ ♠s ❲ s tt t ♦♣s ♣rt② r t t ♦♥rs s ①♣t r♦♠t ② ♦ ♦♥strt♥ t ♠ss

r s♦s s♦♠ ♣r♦ sr ♠ss r③ ♣ ♥ t ②r♦ ♥t♦♥s r tr♣② ♣r♦ ♠♥♠ srs ❬❪ ②♥r s ♥♦t tr♣② ♣r♦ t♦♥② ♣r♦ ♥ ♦♥ rt♦♥ rtss t ♥ ♠s ❲ ♦t♥ t ♣s♥ ♥t♦♥ r♦♠ ♦s♥ t ❯ ♥ ♠ ♦ ♦rs ♦♥ ♦♥ s♦♥

♠♣♠♥tt♦♥ sr ♥ ts st♦♥ s ♥♦t ②t ♣s ♥

Pr♦ ♦♠ ♠sr

s ♦♥t♥t♦♥ ♦ t ♦r ♦♥ ♣r♦ sr ♠s♥ sr ♥ t♦♥ s♦♦r ♦♥ ♦♠♣t♥ ♣r♦ ♦♠ ♠ss s s ♦♥t ♦r t ♦♥♦

♣r♦♠s ♥ s♦t♦♥s ♥ ts s r r② s♠r t♦ t s sr ♥t♦♥ ❲ t♦ ♣t t s♠ tr r♥♠♥t rtr ♦♥ t sr tr♥s♥ t♦♥② t♦ rtr ♦♥ t s ♥ t ♦♠

• s rtr♦♥ ♣♣r ♦♥ ♦♥ t rt♦ t♥ t r♠rs ♥ ts♦rtst ♦ ttrr♦♥

• s rtr♦♥ ♣♣r ♦♥ ♦♥ t rs ♦ t r♠sr♥

♦♠♣tt♦♥ ♦ t t♦ rtr ♦r ♣r♦ ♠s♥ ♥ ♦♥ ♥ t s♠② s t ♦♠♣tt♦♥ ♦ t t rtr sr ♦ r ♦r ①♠♣s♦ ♣r♦ ♦♠ ♠ss ♦♠♣t t t ♦♠ ♠sr ♥ t ♣r♦tr♥t♦♥s

♠♣♠♥tt♦♥ sr ♥ ts st♦♥ s ♥♦t ②t ♣s ♥

Page 89: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

r ♦♠ ♣r♦ sr ♠ss r③ ♣ ♥t♦♥ ②r♦ ♥t♦♥ ②♥r ♣s ♥ ♥t♦♥ ♦rts② ♦s♥

Pr♦ ♦② ♦rt♠

♥ ❱♦r♦♥♦ r♠ ♦② trt♦♥ r♣s t sts ② t ♥tr♦s ♦ tr❱♦r♦♥♦ s ❬♦❪ ♦② ♦rt♠ ♦s r♣t ♦② trt♦♥s ❱♦r♦♥♦r♠ s ♥♦♥ t♦ ♦♥r t♦rs ♥tr♦ ❱♦r♦♥♦ r♠ ② r♣t② ♣♣②♥ ♦② trt♦♥s ❬❪ ♦② trt♦♥s r ♦r ♥st♥ s ♥ ♠s ♦♣t♠③t♦♥ ❬♦❪

r ♠♣♠♥tt♦♥ ♦rs s ♦♦s ♥ rst st♣ t ❱♦r♦♥♦ r♠ ♦ t ♥♣t♣♦♥ts s ♦♠♣t ♥ trt♦♥ t ♥tr♦ ♦ ❱♦r♦♥♦ s ♦♠♣t ♥ ♥♥ st ♦ s ♠♦ t♦ t ♥tr♦ ♦ t s♠ ♥ t ♠♣♠♥tt♦♥ t② r♦♠♣t t ❱♦r♦♥♦ r♠ ♦ t ♥tr♦s r♦♠ srt ❯s♥

♥t♦♥s ♦ t ♣r♦ ♥② tr♥t♦♥ t s strt♦rr t♦ ♠♣♠♥t ♣r♦ rs♦♥ ♦ t ♦② ♦rt♠ ♥t♦♥s rtr♥ t s s ♦♥① st♦ ♣♦♥ts ♥ E

3 s♦ t ♥tr♦ ♦♠♣tt♦♥ ♥ E3 ♥ rs ♥② ♥tr♦ s

♦ts ♦ Dc t ♠st tr♥st ♥s t ♦r♥ ♦♠♥ r ♦r ♥strt♦♥ ♦ ♦r ♣r♦ ♦② s♦tr tt s ♣② s ♠♦ ♥

♥ ♥ ♦♠♣t ♦② trt♦♥s ♦♥ ♣r♦ ❱♦r♦♥♦ r♠s r ♥trst♥ tr♠♥♥ tr t ♥♠r ♦ ♣♦♥ts s ♥ ♥♥ ♦♥ t ♠♥♠♠ ♥ ♠①

Page 90: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣♣t♦♥s

r Pr♦ ♦♠ ♠ss r③ ♣ ♥t♦♥ ♣s ♥ ♥t♦♥♦rts② ♦s♥

r t ♥t ♣r♦ ❱♦r♦♥♦ r♠ ♦ r♥♦♠ ♣♦♥ts t ♦♥r♥tr♦ ❱♦r♦♥♦ r♠ tr ♦t ♦② trt♦♥s

♠♠ r ♥s ♦ t ♣r♦ ♥② tr♥t♦♥ ❲ ①♣t ♥ ♥sr t♦ts qst♦♥ t♦ s ♥ ♠s ♦♣t♠③t♦♥ ❬❱❪ ❲ t ♦♦♥ ①♣r♠♥t ❲♦♠♣t t ♣r♦ ♥② tr♥t♦♥ ♦ st ♦ n ♥♦r♠② strt r♥♦♠♣♦♥ts ♥ Dc ♥ r♥ ♦② trt♦♥s ♥t t ♠♥♠♠ ♥ ♠①♠♠ r♥ ♦ t♦ ♦♥st ♦② trt♦♥s ♥♦t r ② ♠♦r t♥ 0.01 ♦r 10 ♦♥st trt♦♥s ❲ r♥ ♥♣♥♥t ①♣r♠♥ts ♦r n t♥ 1 ♥ 100 sr

❯♥♦rt♥t② t rsts ♦ ts ①♣r♠♥t r ♥♦t r② ♦♥s ♦r s♠ ♣♦♥tsts r② ♦♦ ①tr♠ r ♥s ♥ tt♥ ♦r ♦r r ♣♦♥t stst rsts r ♠ ss r s♣② s♥ t rsts ♣♥ ② ♦♥ t strt♥♦♥rt♦♥ ♦r ♣♦♥t sts ♦ ♦t ♣♦♥ts ♥ ♦t ♣♦♥ts s tt s♦♠ ♦t strt♥ ♦♥rt♦♥s ♥ ② r② ♦♦ rsts

Page 91: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♠♣♠♥tt♦♥

020406080

100120140160180

0 10 20 30 40 50 60 70 80 90 100

max anglemin angle

angle

n

r ♥♠♠ ♥ ♠①♠♠ r ♥ ♦ ♣r♦ ♥② tr♥t♦♥♦ n ♣♦♥ts tr ♦② trt♦♥s

♦♥s♦♥

♥ ts ♣tr ♣rs♥t ♦r ♠♣♠♥tt♦♥ ♦ ♣r♦ tr♥t♦♥s tt s♣② tr♦ t ♦♣♥ s♦r rr② ❲ sr ♦r ♠♣♠♥tt♦♥s s t s♠rts ♥ t r♥s t♦ t tr♥t♦♥s ❲ ♥♦r ♦♥ t ♦♠♣①t② ♦ t ♠♥ ♥t♦♥s ♥ s♦♠ ♥trst♥ ♥t♦♥s tt rs♣ t♦ T

3 ♥ ①♣r♠♥ts ♦♥ ♦t ♥rt ♥ r♦r t r② t ♥②♦ ♦r ♠♣♠♥tt♦♥ ♥ t ♦r r♥♦♠ ♣♦♥t sts ♦r ♠♣♠♥tt♦♥ tr♥s ♦t t♦ ♦♥② ♦t t♠s s♦r t♥ t ♦♠♣tt♦♥ ♦ t ♥② tr♥t♦♥ ♦ E

3s s rt ♠♣r♦♠♥t ♦♠♣r t♦ t t♦r ♦ t st ♥ ♦♠♣t♥ t ♦♣s ♦ ♣♦♥t ♥② s♦ s♦♠ ①♠♣r② ♣♣t♦♥s r t ♣r♦ tr♥t♦♥s ♥ s ♥st ♦ t tr♥t♦♥s rqr♥ ♦♥② ♠♥♦r♣tt♦♥s

t♦r ♥ ♠♣r♦ t♦ s♥ trts ss s♣③ t♦ t ♥t

Page 92: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣tr

♥② tr♥t♦♥s ♦ ♦tr

s♣s

♥ ts ♣tr ♥r③ t rsts ♦ ♣tr t♦ ♦tr s♣s ♦r s♣② ♦♥sr tr sss ♦ ♦rt s♣s

t s♣s s♣s ♦ ♦♥st♥t ♠♥♥♥ rtr ③r♦ s r ♦rt s♣s♦ E

d

s♣s ♦ ♦♥st♥t ♣♦st rtr ♦rt s♣s ♦ t d♠♥s♦♥ s♣rS

d

s♣s ♦ ♦♥st♥t ♥t rtr ♦rt s♣s ♦ t d♠♥s♦♥ ②♣r♦s♣ H

d

st ss s ♠ rr t♥ t t♦ ♦ ❲ ♦♥② ♣r♠♥r② sss♦♥♦♥ t s♣ s ♦ t ♦ t♦rs

Pr♠♥rs

♥♠r ♦ ♥t♦♥s ♥ ♣tr ♥ ♥r③ t♦ ♦r ♦♥ rtr r♦ ss♦ ♦rt s♣s ♥♥ s♣s ♦ r♥t rtr r ♥r③ rs♦♥s♦ ts ♥t♦♥s tt r rs ♥ t ssq♥t st♦♥s

t M d♠♥♦ t t ♦♦♥ ♣r♦♣rts

r s ♥t♦♥ ♦ t ♥② tr♥t♦♥ ♦ M ♥ ② st ♦ ♣♦♥ts ♥M

♥ ♦rt♠ ♦r ♦♠♣t♥ t ♥② tr♥t♦♥ ♦ M r♦♠ ♥ ♣♦♥t sts ♥♦♥

♥ ts ♣tr sss t ss ♦ M = Ed M = S

d ♥ M = Hd

t G srt r♦♣ ♦ s♦♠trs t♥ ♦♥ M ♥ X := M/G t ♦rt s♣ ♦ M

♥r t t♦♥ ♦ G t ♣r♦t♦♥ ♠♣ π : M → X ♦ t♦ ♦♥sr tr♥t♦♥s♦ X ♦r♥ t♦ ♥t♦♥ rst ♥t♦♥ ♦r s♠♣① ♥ X s s ♥♠♠t ①t♥s♦♥ ♦ t ♥t♦♥ ♦ s♠♣s ♥ t t t♦rs ♥t♦♥

Page 93: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥② tr♥t♦♥s ♦ ♦tr s♣s

♥t♦♥ ♠♣① ♥ M t σ ks♠♣① ♥ M t rstrt♦♥ π|σ ♦ πt♦ σ s ♥t t ♠ ♦ σ ② π s ks♠♣① ♥ X

♥tt② ts ♥t♦♥ rqrs s♠♣s ♥♦t t♦ s♥trst ♥ t ♦rt s♣ ❲rt DT (Q) t♦ ♥♦t t ♥② tr♥t♦♥ ♦ M ♥ ② ♣♦♥t st Q t P ♣♦♥t st ♥ M ❲ ♥ ♥♦ ♣t ♥t♦♥ t♦ t ♥② tr♥t♦♥ ♦X ♥ ② π(P)

♥t♦♥ ♥② tr♥t♦♥ ♦ X π(DT (GP)) s tr♥t♦♥ ♦ X

ss♠s tt t s s♠♣ ♦♠♣① ♦r♥ t♦ ♥t♦♥ t♥ t t ♥② tr♥t♦♥ ♦ X ♥ ② π(P)

❲ ♥tr♦ s♦♠ s ♥♦t♦♥s r♦♠ r♦♣ t♦r② tt r s tr ♦♥ t G r♦♣ ♥ H ♥♦t sr♦♣ ♦ G H s ♥♦r♠ ♥ G t s ♥r♥t ♥r♦♥t♦♥ ♦r h ∈ H ♥ g ∈ G ghg−1 ∈ H ♦r r♦♣ ♠♥t g ∈ G tst gh | h ∈ H s ♦st ♦ H ♥ G ♥① ♦ sr♦♣ H ♥ G s ♥ st ♥♠r ♦ ♦sts ♦ H ♥ G

♥ t ssq♥t st♦♥s ♣r♦ ♣t rs♦♥s ♦ ♦r♠ ♥ ♣r♦ s♦♠♦♠tr tsts t♦ tr ♥ ♣♦♥t st ♥s tr♥t♦♥ ♥ X = M/G♦r r♥t sss ♦ s♣s M ♥ r♦♣s G

t s♣s

♥ ts st♦♥ ♦♥sr d♠♥s♦♥ t s♣s t t♦rs sss ♥ ♣tr s s♣ s ♦ t s♣s ♦♥sr ♥ ts st♦♥ ❲ t ♥② tr♥t♦♥ ♦t t t♦rs s t ♥s ♦ ♠♥② ♣♣t♦♥ s s♦♠ ♦ t♠ ♦♠♣tt♦♥♦♦② ❬r❪ rqr ♠♦r ♥r ♠♥♦s tt r ♦rt s♣s ♦ E

3 ♥r t t♦♥♦ ♦tr r②st♦r♣ r♦♣s

❲ rst ♥tr♦ ♦s ♥ d♠♥♦s ♥ tr ♣r♦♣rts t♦♥ t♥ sts ♥② tr♥t♦♥s ♦ ♦s ♥ d♠♥♦s ♥ s♦s s♥ tr t♦r♠ tt tr s ②s ♥t②st ♦r♥ s♣ ♦ t ♠♥♦♥ t ♥② tr♥t♦♥ s ♥ ♦r ♥② st ♦ ♣♦♥ts t♦♥ sssst ♥r③t♦♥ ♦ ♦rt♠ s ♣ t♦ ♦s ♥ ♠♥♦s ♦st♦♥♣ts ♠♥t♦♥ ♦ r t♥ r♦♠ ❬❪

♦s ♥ ♠♥♦s

♦s ♠♥♦ s ♦♠♣t ♠♥♦ t♦t ♦♥r② d♠♥♦ s ♥ ♦r t r② ♣♦♥t s ♥♦r♦♦ s♦♠tr t♦ ♥♦r♦♦ ♥ E

d d♠♥s♦♥ r r♦♣ GB s srt r♦♣ ♦ s♦♠trs ♦ E

d s ttt ♦rt s♣ E

d/GB s ♦♠♣t r♦♣s r s♦ r②st♦r♣ r♦♣s ♦rs♣ r♦♣s ❬❪

♦r♠ r ❬❪

• t GB d♠♥s♦♥ r r♦♣ r s r♦♣ GT ♦ d ♥r②♥♣♥♥t tr♥st♦♥s tt s ♥♦r♠ sr♦♣ ♦ GB ♦ ♥t ♥① r♦♣GT s tr♥st♦♥ sr♦♣ ♦ GB

Page 94: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

t s♣s

• ♦r ♥② d tr s ♦♥② ♥t ♥♠r ♦ d♠♥s♦♥ r r♦♣s ♣ t♦s♦♠♦r♣s♠

♦t tt t ♦rt s♣ Ed/GB s ♥♦t ♥ssr② ♠♥♦ GB s ♣♦♥ts

① ts ♣♦♥ts ♦ ♥♦t ♥♦r♦♦ ♥ Ed/GB tt s ♦♠♦♠♦r♣ t♦

♥♦r♦♦ ♥ Ed ♦rt s♣ E

d/GB ♥ ②s sr ② t ♠♦r ♥r♦♥♣t ♦ ♥ ♦r♦ ❬P ❪ ♦r t ♦rt s♣ t♦ ♠♥♦ t r♦♣ ♦t♦♥ ♥♥ t ♠st ♥♦t ① ♣♦♥ts ♥ ♦tr ♦rs t r♦♣ ♦ t♦♥ ♠st t♦rs♦♥r t ♥tt② ♠st t ♦♥② ♠♥t ♦ ♥t ♦rr GT s sr♦♣♦ d ♥♣♥♥t tr♥st♦♥s ♦ GB t♥ E

d/GT s dt♦rs t s s♥t t♦ ♦♥srt♦rs♦♥r r r♦♣s t♦ ♦♠♣t② ss② ♦s ♥ ♠♥♦s

♦r♠ ❬❪ ♥② ♦s ♥ d♠♥♦ s q ♣ t♦ ♦♠♦r♣s♠t♦ ①t② ♦♥ ♦rt s♣ E

d/GB r GB s t♦rs♦♥r d♠♥s♦♥ rr♦♣

♦r♥ t♦ ♦r♠ tr r ♦♥② ♥t② ♠♥② d♠♥s♦♥ rr♦♣s ♣ t♦ s♦♠♦r♣s♠ ♥ ♠♥s♦♥ 2 tr r 17 ♥ ♠♥s♦♥ 3 tr r 230 ♥♠r ♦ r r♦♣s ② ♠♥s♦♥ s ss♥ t ♥ t ♥♥♥②♦♣ ♦ ♥tr q♥s ❬♦❪ t② r ♥♦♥ ♣ t♦ ♠♥s♦♥ ♥♠r ♦t♦rs♦♥r r r♦♣s s ss♥ t t② r ♥♦♥ ♣ t♦ ♠♥s♦♥

♥ t♦ ♠♥s♦♥s tr r ♦♥② t♦ t♦rs♦♥r r r♦♣s ♥ ts t♦♦s ♥ ♠♥♦s ♣ t♦ s♦♠♦r♣s♠ t t♦rs ♥ t ♥ ♦tt ♥ tr♠♥s♦♥s tr r ♦s ♥ ♠♥♦s ♦r ♦ r ♥♦♥♦r♥t sst♦♥ s ♥ ♥ ❬❲❪ ♥ ❬❪

• tr ♥r② ♥♣♥♥t tr♥st♦♥s t♦rs

• ♦♥ sr ♠♦t♦♥ ♥ t♦ ♥r② ♥♣♥♥t tr♥st♦♥s ♦rt♦♦♥ t♦ t sr ♠♦t♦♥ ♥ r♦tt ② π 2π/3 π/2 π/3

• tr ♦rt♦♦♥ sr ♠♦t♦♥s tt r♦tt ② π

• t♦ ♥r② ♥♣♥♥t rt♦♥s ♥ ♣♥ r r t♦ r♥t r♦♣s♥rt ♥ ts ②

• ♦♥ rt♦♥ ♥ ♦♥ sr ♠♦t♦♥ tt r♦tts ② π ♦t ♥ ①s ♣r t♦t rt♦♥ ♣♥ ♥ ♦rt♦♦♥ t♦ t tr♥st♦♥ ❲tr t sr ①s s♥s t rt♦♥ ♣♥ ♦r ♥♦t ②s t♦ r♥t ♠♥♦s

rst s① ♠♥♦s r ♦r♥t ♥ t ♦r st ♦♥s r ♥♦t s tr♥rt♦rs ♦♥t♥ rt♦♥s

r♥t♦♥s ♦ ♦s ♥ ♥♦s

t GF t♦rs♦♥r d♠♥s♦♥ r r♦♣ P ♥t ♣♦♥t st ♥ Ed X :=

Ed/GF ♦s ♥ ♠♥♦ t ♣r♦t♦♥ ♠♣ π : E

d → X ♥ DT (GFP) t♥② tr♥t♦♥ ♦ E

d ♥ ② t ♥♥t ♣♦♥t st GFP♦r t sss♦♥s ♦ ♥ t ♦♦♥ t♦ s

Page 95: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥② tr♥t♦♥s ♦ ♦tr s♣s

♠♥♠♠ st♥ δ(G) ② r♦♣ G ♠♦s ♣♦♥t

δ(G) = minp∈Ed,g∈G,g 6=1G

st(p, gp),

r 1G ♥♦ts t ♥t ♠♥t ♦ G ♦t tt G s t♦rs♦♥r ♥ srtt♥ δ(G) > 0 ♦s

♠tr ∆(S) ♦ t rst d B ♥ Ed tt ♦s ♥♦t ♦♥t♥ ♥② ♣♦♥t ♦

st S ♥ ts ♥tr♦r

❲ ♥♦ ♥r③ ♦r♠ ♣

♦r♠ t st♦♥ ♦ π(DT (GFP)) ♦s ♥♦t ♦♥t♥ ②s ♦ ♥t ≤ 2t♥ π(DT (GFP)) s tr♥t♦♥ ♦ X

♦st ♣rts ♦ t ♣r♦♦ ♦ ♦r♠ r ♦♠♣t② ♦♠♥t♦r ♥ ♦ ♥♦t♣♥ ♦♥ t s♣ ♣r♦♦ ♦ ♠♠ s s ♦♥ t t tt t rstrt♦♥ ♦π t♦ s♠♣① s ♦♠♦♠♦r♣s♠ srt♦♥ ♦♦s rt② r♦♠ ♠♠ ♥ t s♠♣ ♦♠♣① ♥t♦♥ ♣r♦♦s ♦ ♠♠s ♥ r♥ s ♦♥ ♠♠ ♥ t ♣r♦♣rts ♦ π s ♣rt r♦♠ ♠♠ t♦ sss♦♥ ♦ t♦♥ rt② ♥r③s t♦ ♦s ♥ d♠♥♦s ❲♥♦ ♣r♦ t ♥r③ rs♦♥ ♦ ♠♠

♠♠ t K st ♦ s♠♣s ♥ Ed ♦s rts r ①t② t ♠♥ts ♦

GFP ♥ tt s ♦♥t♦♥s ♥ ♦ ♥t♦♥ ♥ t ♥② ♣r♦♣rt②t rs♣t t♦ GFP ♥ K stss t ♦ ♥t♥ss ♣r♦♣rt② s s Ks s♠♣ ♦♠♣①

Pr♦♦ ❲ rst ♦♥sr ♣♦♥t p tt s rt① ♥ K ♦t tt δ(GF ) > 0 ♥ ∆(GFP) <∞ ♦ s GF s t♦rs♦♥r r r♦♣ ♦♥st ♦ K s ♦♥② ∆(GFP) ♥ ts ♥② ♣♦♥t ♥♥t t♦ p ♠st ♥ ♦ rs ∆(GFP) ♥trt p s GF s srt t ♥♠r ♦ ♣♦♥ts ♦ GFP tt ♥s s s ♥t♦♦♥② p s ♥♥t t♦ ♦♥② ♥t② ♠♥② s♠♣s

t s ♥♦ ♦♥sr ♣♦♥t p ♥ Ed tt s ♥♦t rt① ♥ K t σ ♥♦t t s♠♣①

tt ♦♥t♥s p ♥ ts ♥tr♦r ♥ t vσ ♥♦t rt① ♦ σ t St(vσ) ♥♦t t st ♦s♠♣s tt vσ s ♥♥t t♦ ♦ s♦♥ tt St(vσ) ♦♥t♥s ♦♥② ♥t②♠♥② ♠♥ts st St(σ) ♦ s♠♣s tt σ s ♥♥t t♦ s sst ♦ St(vσ) tst s ♥t r s ♥♦r♦♦ U(p) tt s ♥♦♥♠♣t② ♥trst♦♥ t ①t② t♠♥ts St(σ)

rtr♦♥ ♠♥t♦♥s t trs♦ 12 ♣♥s ♦♥ t r♦♣ G ♥r

③ rs♦♥ ♦ ts ♦r♦r② ♦♦s ② s♠♣ ♦♠tr rs♦♥♥ r♦♠ ♦r♠

♦r♦r② ∆(GFP) < δ(GF )2 t♥ π(DT (GFP ′)) s tr♥t♦♥ ♦ X ♦r ♥②

♥t P ′ ⊇ P

♦r ♥② t♦rs♦♥r r r♦♣ tr r ♣♦♥t sts s tt t ♦♥t♦♥ ♦♦r♦r② s s δ s strt② ♣♦st ♥ ∆ ♥ ♠ rtrr②s♠ ② t ♦ ♦ t ♣♦♥t st

♥② ♥r③ rs♦♥ ♦ ♠♠

Page 96: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

t s♣s

♠♠ r s ♥♦r♠ sr♦♣ GC ♦ GF ♦ ♥t ♥① s tt t ♣r♦t♦♥♦ t ♥② tr♥t♦♥ ♦ GFP ∪ GCQ ♥ E

d ♦♥t♦ XC = Ed/GC s tr♥t♦♥

♦r ♥② ♥t ♣♦♥t st P ♥ Ed ♥ ♥② Q ⊆ GF q t ♥② q ∈ E

d

Pr♦♦ ♦r♥ t♦ ♦r♠ tr s r♦♣ GT ♦ d ♥r② ♥♣♥♥t tr♥st♦♥s tt s ♥♦r♠ sr♦♣ ♦ GF t ♥t ♥① h′ ❲ ♦♦s ♥rt♦rs g1, . . . , gd

♦ GT ♥ t ♦♦♥ ② t g1 t s♦rtst tr♥st♦♥ ♥ GT t gi+1 t s♦rtst tr♥st♦♥ ♥ GT tt s ♥r② ♥♣♥♥t ♦ t tr♥st♦♥s g1, . . . , gi ♦t tt∆(GT p) ♦s ♥♦t ♣♥ ♦♥ s♣ ♦ ♦ p ♥ ts ♥ ♦♥sr ♦♥st♥t ❲♥ ♥ ♥ ♥tr ♦♥t c s tt ♦r gi t ♥qt② st(p, gc

i p) > 2∆(GT p)♦s ♦r ♥② p ∈ E

d r♦♣ GC ♥rt ② gc1, . . . , g

cd s sr♦♣ ♦ GT ♦ ♥①

cd t t ♣r♦♣rt② δ(GC) > 2∆(GT p) ♦r ♥② p ∈ Ed s GT s ♥♦r♠ ♥ GF

ggT g−1 ∈ GT ♦r g ∈ GF , gT ∈ GT ② ♦♥strt♦♥ ♦ GC tr s t♦♥ t♥t gT ∈ GT ♥ t gC ∈ GC ♥ ② gC = gc

T ♦ t s s② t♦ s tt GC s ♥♦r♠sr♦♣ ♦ GF t ♥① h = h′ · cd ♦t tt ∆(GCGFP) = ∆(GFP) ≤ ∆(GT p) ♦r ♥②p ∈ E

d s ∆(GCGFP) < δ(GC)2 ♦s ♥ ♦r♥ t♦ ♦r♦r② t ♣r♦t♦♥

♦ t ♥② tr♥t♦♥ ♦ GCGFP = GFP ♦♥t♦ XC ♦r♠s tr♥t♦♥ r♠♥s tr ♥ ♥ ♥ rtr ♣♦♥ts

♦t tt t ♣r♦♦ s ♦♥strt t srs ♦ t♦ ♦♥strt GC r♦♠ GT r♦♣ GT ♥ ♦♥strt r♦♠ GF s♥ t ♠strrr ♦rt♠ ❬♠❪ ♥ ♠♣♠♥tt♦♥ ♦ t ♠strrr ♦rt♠ s ♦r♥st♥ ♥ P ❬♣❪ ♠♠ ♠♥s tt tr ①sts s♣ XC ♥ t♣♦♥t st π(P) ♥s ♥② tr♥t♦♥ s♣ XC s ♦r♥ s♣ ♦ X t ♥t ♥♠r ♦ sts ❬r♠❪ ♠♠ ♥ s♦ ♥rst♦♦ ② ♦♥strt♥XC r♦♠ X rt② s ♦♦s

♦s ♥ d♠♥♦ s dt♦rs s ♦r♥ s♣ t ♥t ♥♠r ♦sts s ♦♦s r♦♠ ♦r♠ s sss ♦ ♥♠♥t ♦♠♥ ♦ tdt♦rs s d♠♥s♦♥ ②♣r♣r♣♣ ② ♥ t♦ ♦ ts ②♣r♣r♣♣st♦tr t ♥ ♦r♥ s♣ tt s ♥ dt♦rs ❲ ♥ ♦♥strt XC ②♥ s ♠♥② ♦♣s ♦ t ♥♠♥t ♦♠♥ s ♥ssr② t♦ t ♦♥t♦♥ ♥♦r♦r② ∆(GCGFP) = ∆(GFP) < δ(GC)

2 r ♦r ♥ strt♦♥ ♥t♦ ♠♥s♦♥s

r ♥t ♥♠r ♦ ♦♣s ♦ t ♥♠♥t ♦♠♥

s ♥ ①♠♣ ♦♥sr t t ♥ ♦tt E2/GK r GK s t r♦♣ ♥rt

② tr♥st♦♥ gt ♥ rt♦♥ gg tt s rt♦♥ t♦tr t tr♥st♦♥♣r t♦ t rt♦♥ ①s s r r♦♣ ♥rt ② gt ♥ g2

g s

Page 97: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥② tr♥t♦♥s ♦ ♦tr s♣s

tr♥st♦♥ sr♦♣ ♦ GK ♦ ♥① ♦ ♥ ♦♦s sr♦♣ ♦ ts tr♥st♦♥sr♦♣ t ♥t ♥① tt s t ♦♥t♦♥ ♦ ♠♠ s ♥ r

r ♣rt ♦ t ♥♥t ♣♦♥t r GKp

♦t tt ♥ ♦t ♦r♦r② ♥ ♠♠ t t ♦♥t♦♥ ♦ t♦r♠ ∆ < δ

2 ♥ ♦r♦r② ♣t t ♣♦♥t st P t♦ rs ∆ ♥ ♠♠ ♣t t r♦♣ GC t♦ ♥rs δ

♦rt♠

♦rt♠ ♥r③s t♦ X = Ed/GF s♥ t rsts ♥ ♥ t ♣r♦s st♦♥

♦rt♠ s ♥r♠♥t t ♣♦♥ts ♦ P r ♦♥ ② ♦♥

• ♦rt♠ tr♠♥s GC r♦♠ GF s sr ♥ t♦♥

• ♥ t ♦rt♠ strts ♦♠♣t♥ ♥ t hst ♦r♥ s♣ XC = Ed/GC

s ♥ ♠♠ ♥srt♥ h ♦♣s ♣r ♥♣t ♣♦♥t r ♦♣② ♦ ♣♦♥tp ♥ ♠♥t ♦ ts ♦rt ♥r t t♦♥ ♦ t q♦t♥t r♦♣ GF /GC ♣♦♥tgp ♦r g ∈ GF /GC

• ♥ t ♦♥t♦♥ ♦ ♦r♦r② s ♠t ♦r t rr♥t ♣♦♥t st t ♦rt♠sts t♦ ♦♠♣t♥ ♥ X ♥ ♦♥t♥s t♦ ♥srt ♦ t r♠♥♥ ♣♦♥ts ♦♥②♦♥

P s s tt t ♦♥t♦♥ ♦ ♦r♦r② s ♥r t♥ t ♦rt♠rtr♥s t tr♥t♦♥ ♦ t ♦r♥ s♣ XC

♦ sss ♣♣r ♥♠② ♦ t♦ st♦r t rr♥t tr♥t♦♥ ♥ ♦ t♦ ♥srt ♣♦♥t

♣♥t t strtr

tr♥t♦♥ ♥ st♦r s r♣ ♥ t ♦♦♥ ② ♠♥s♦♥ s♠♣sr st♦r t st ♦ tr rts ♥ ♥♦rs rt① ♦♥t♥s t ♦♦r♥ts♦ t ♣♦♥t t ♦rrs♣♦♥s t♦ t♦♥② ds♠♣① st♦rs t ♥♦r♠t♦♥ ♦♥ ♦t♦ ♠♣ t s♦♠tr② ♥t♦ E

d ♥ ♣♣r♦♣rt ♠♥t ♦ t s♠♣① ♣r♠ ♥rt ♣r♦t♦♥ ♠♣ π ♦r ts ♣♣r♦ s ♥♦t r② s♣ ♥t s♥ ♦r r♠♥s♦♥s t ♥♠r ♦ ds♠♣s ♥ tr♥t♦♥ ♥ r♦ r② r ♠♦r s♣♥t ♣♣r♦ s t♦ st♦r t st♦♥ ❬❪ ♥ ts s ♠st sr ② ts t♦ rts t♦tr t tr ♦sts r t ♦sts r ♠♥ts ♦GC ♦r GF rs♣t② ds♠♣① ♥ t♥ ♦♥strt ② tr♥st♥ s stt tr ♦sts t ♦♠♠♦♥ rts r s r

Page 98: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣r s♣s

r t r s t (10

)t♦ ♦t ♦sts ♦ e3 t♦ ♦r♠ t tr♥

pqr

P♦♥t ♥srt♦♥

♦r t ♣♦♥t ♥srt♦♥ t ♣♣r♦ ② ♦②r ❬♦❪ ♥ ❲ts♦♥ ❬❲t❪ ♥ s X s ♦r♥t t ♥srt♦♥ r♦t♥ ♥srs tt t strtr ♦♥② st♦rs♣♦st② ♦r♥t s♠♣s X s ♥♦♥♦r♥t ts s ♥♦t ♣♦ss ♥ ts s ♠st ♣♣② ♥ ♦r♥tt♦♥ tst ♦♥ t ♣r♠ ♥r π ♦ t s♠♣① rst ♦r tst♥tr t ♣♦♥t s ♥s ♦r ♦ts t rs♣t d

t ♦r♦s

♥tr qst♦♥ s ♦ t ①t♥ t rsts t♦ ♥r ♦r♦s rsts ♦t♦♥ ① r r♦♣s t ① ♣♦♥ts ♦r r♦♠ t rt♦r♠ ♥♦ tt ♥② ♦r♦ s ♥t② st ♦r♥ s♣ tt s ♦s♥ ♠♥♦ ♥ ♦♥ ♦r ♣♣r♦ ♦rs ♦ t ♣♣r♦ ♥♥♦t♦♠♣t tr♥t♦♥ ♥ t ♦r♦ t ♥ ②s ♦♠♣t ♥② tr♥t♦♥♥ tt ♦r♥ s♣

♣r s♣s

♥ ts st♦♥ ①t♥ t ♣♣r♦ sr ♥ ♣tr ♦♥t♦ ♦rt s♣s ♦ s♣r♥r t t♦♥ ♦ srt r♦♣ ♦ s♦♠trs ❲ rst sss ♥② tr♥t♦♥s♦ t s♣r ♥ ♥t② t ♦rt s♣s tt ♦r ♣♣r♦ ♥ ♥ ♥ ♥②sss t ♥② tr♥t♦♥ ♦ s♣r ♦r♦

r♥t♦♥s ♦ t s♣r

t Sd ♥♦t d♠♥s♦♥ ♥t s♣r ♥ ♦rr t♦ s ♥t♦♥s ♥

♠st ♥t♦♥ ♦r s♠♣s ♥ t ♥② tr♥t♦♥ ♦ t d♠♥s♦♥s♣r ♦♦♥ ♥t♦♥s r strt♦rr ①t♥s♦♥s ♦ t t s

t ρ : Ed+1 −0 → S

d ♥♦t t r ♣r♦t♦♥ ρ ♣r♦ts ♣♦♥ts ♦ r②R strt♥ t t ♦r♥ ♦♥t♦ t ♥trst♦♥ ♣♦♥t ♦ R ♥ S

d

♥t♦♥ ♣r s♠♣① t Q st ♦ k +1 ♣♦♥ts ♥ Sd t k ≤ d t

(Q) ♥♦t t ♦♥① ♦ Q ♥ Ed+1 (Q) ♦s ♥♦t ♦♥t♥ t ♦r♥

t ♠ ♥r ρ ♦ (Q) s♣r ks♠♣①

r♠sr♥ ♦ s♣r ds♠♣① ♥ ♥ ♥ t s♠ ② s ♦rE

d s♥ t s♣r ♠tr t ♥ ♦♥strt s ♦♦s ♦♥sr t (d − 1)

Page 99: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥② tr♥t♦♥s ♦ ♦tr s♣s

♥ ② t d rts ♦ t s♠♣① ②♥ ♥ (d−1)②♣r♣♥ ♥ Ed ♣r♦t♦♥

♥r ρ ♦ ts (d − 1) s t r♠sr♥ ♦ t ds♠♣①

♥t♦♥ ♣r ♥② tr♥t♦♥ ♥② tr♥t♦♥ ♦ P♥ S

d s tr♥t♦♥ ♦ Sd s tt t r♠sr♥ ♦ ds♠♣① ♦ t

tr♥t♦♥ ♦s ♥♦t ♥② ♣♦♥t ♦ P ♥ ts ♥tr♦r

♥② tr♥t♦♥ ♦ t s♣r Sd ♥ ② P s t ♦♥① ♦ P ♥

Ed+1 s P s ♥ t d♠♥s♦♥ s♣r ♠ ♥ E

d+1 ♣♦♥ts ♦ P ♣♣r ♥ts ♦♥① ♥ E

d+1 t s ♠♦r ♥t t♦ rt② ♦♠♣t t ♥② tr♥t♦♥♥ d♠♥s♦♥ s♣ ♥st ♦ rs♦rt♥ t♦ E

d+1 ❬❪ sr ♦ t♦ ♦♠♣t s♣r ❱♦r♦♥♦ r♠ ♥ t♦ ♠♥s♦♥s ② ♦♠♣t♥ t♦ ♣♥r ❱♦r♦♥♦ r♠s♥ ❬+❪ sr t♦ ♣♣r♦s ♥ ♥ ♠♣♠♥tt♦♥ ♦r t s ♦ d = 2s ♣♣r♦s s t ♦rt♠ ♦r ♦♠♣t♥ t ♥② tr♥t♦♥ ♥ E

2 ♥♣t t ♣rts ♦r♥② t♦ t ♦rrt rsts ♦r t ♥② tr♥t♦♥♦ t s♣r

♣♣r♦s sss ♥ ❬+❪ ①t♥ t♦ d ♠♥s♦♥s ♣rt t♦ tsttr t r♠sr♥ ♦ ds♠♣① ♦♥t♥s ♥ ♣♦♥t ♥ ♦♠♣ts ♦♦s t σ s♣r ds♠♣① rts ♦ σ ♥ d♠♥s♦♥②♣r♣♥ ♥ E

d+1 t p ♥♦t t qr② ♣♦♥t p ♥ t ♦r♥ ♦♥ r♥t ss♦ t ②♣r♣♥ t♥ p s ♥s t r♠sr♥ ♦ σ

t ♣♦♥ts ♦ P ♥ s♣r P ♦s ♥♦t ♥ ♥② tr♥t♦♥ ♦ S

d ♥ ♦rr t♦ ♥② tr♥t♦♥ tt s ♦♠♦♠♦r♣ t♦ Sd

♥ ♦r ♥st♥ ♥tr♦ rt rt① s♠r t♦ t rt① t ♥♥t② ♦r ♥②tr♥t♦♥s ♦ E

d s t♦♥

♣r ♦rt s♣s

♥ s♠r ♠♥♥r s ♥ t♦♥ ♦r ♣♣r♦ ♦rs ♦r d♠♥s♦♥ srt r♦♣s♦ s♦♠trs ♦ t s♣r S

d r♦♣ ♦ s♦♠trs ♦ t d♠♥s♦♥ s♣r s t♦rt♦♦♥ r♦♣ O(d + 1) srt sr♦♣s ♦ O(d + 1) r ♥t s ts♣r s ♦♠♣t trs t ♦rt ♦ ♣♦♥t ♦ ♥♥t ♥ ♥♥t ssts♦ ♦♠♣t s♣ ♥ ♠t♦♥ ♣♦♥t ♥ r ts ♥♦t srt srtsr♦♣s ♦ O(d + 1) r ♣♦♥t r♦♣s ♥ ♦r ♠♥s♦♥ tr r ♥♥t②♠♥② ♦ t♠ ❲ r② sss t t♦ ♥ tr♠♥s♦♥ ♣♦♥t r♦♣s

r r t♦ t②♣s ♦ ♥t ♣♦♥t r♦♣s ♥ t♦ ♠♥s♦♥s ② r♦♣s Cn♥rt ② r♦tt♦♥ ♦ 360/n r r♦♣s ♥rt ② r♦tt♦♥ ♦ 360/n♥ rt♦♥ s r ♦r ♥ strt♦♥

♥ tr ♠♥s♦♥s tr r s♥ srs ♦ ♣♦♥t r♦♣s ♦ ♦♥t♥s ♥♥♥t ♥♠r ♦ r♦♣s ♥ s♥ ♠♦r ♣♦♥t r♦♣s s♥ ♥♥t srs r♦tt♦♥ ♦ 360/n ♦r ♥② n > 0 s ♦♥ ♥rt♦r r♠♥♥ s♥ ♣♦♥t r♦♣sr t s②♠♠tr② r♦♣ ♦ t ttrr♦♥ t♦tr t t♦ sr♦♣s s s ts②♠♠tr② r♦♣s ♦ t ♦tr♦♥ ♥ t ♦sr♦♥ t ♦♥ sr♦♣ ♦rrtr r♥ s ❬♦①❪

♦t tt ♠♦♥ t tr♠♥s♦♥ ♣♦♥t r♦♣s t ♦♥② r♦♣ t♦t ①♣♦♥ts s t r♦♣ tt ♠♣s ♣♦♥t t♦ ts ♥t♣♦ ♣♦♥t ♦♥ t s♣r ♦rts♣ ♥r t t♦♥ ♦ ts r♦♣ s t ♣r♦t ♣♥ s ts t ♦♥② t♦♠♥s♦♥ s♣r ♠♥♦ ss t s♣r ts ♦tr ♦rt s♣s r t②♦r♦s ❬t❪

Page 100: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣r s♣s

r t C3 r♦tt♦♥ ♦ 360/3 t D5 r♦tt♦♥ ♦ 360/5 ♥ rt♦♥ s rs D r t rs♣t ♥♠♥t ♦♠♥s

r♥t♦♥s ♦ s♣r ♦rt s♣s

♥r③t♦♥ ♦ ♦r♠ ♥ ♦rt♠ s s♠r t♦ t♦♥ ♠♥ r♥ s tt t ♥♠r ♦ r♦♣s t♦ ♦♥sr s ♥♥t t r♦♣s t♠ss r ♥t

t GP ♥♦t d♠♥s♦♥ ♣♦♥t r♦♣ X := Sd/GP ♥ ♦rt s♣ t ♣r♦t♦♥

♠♣ π : Sd → X ♥ DT (GPP) t ♥② tr♥t♦♥ ♦ S

d ♥ ② t ♥t♣♦♥t st GPP

❲ ♥♦ ♥r③ ♦r♠

♦r♠ t st♦♥ ♦ π(DT (GPP)) ♦s ♥♦t ♦♥t♥ ②s ♦ ♥t ≤ 2t♥ π(DT (GPP)) s tr♥t♦♥ ♦ X

♦r t♦♥ t ♥t♦♥s ♥ ♠♠s ♦ t♦♥ ♥r③ rt②t♦ X ①♣t ♠♠ ♦r t ♣r♦♦ ♦ ♠♠ tr♥s ♦t t♦ tr ♥t s♣r s s GPP s ♥t ♥ s♦ DT (GPP) s ♥t t♦♦

s GPP s ♥t ♥ ②s ♦♦s t s♣r Sd s ♥t ♦r♥ s♣ ♦ X ♥

t ♣♦♥t st GPP ♥s tr♥t♦♥ t ♦♥t♥s ♠♦r t♥ d + 2 ♣♦♥ts ♥♦t t♥ ♦♥ s♣r

❲t t ♠♦t♦♥s sr ♥ t♦♥ t ♥r♠♥t ♦rt♠ ② ♦②r♥ ❲ts♦♥ ♦rs ♦r ♦♠♣t♥ t ♥② tr♥t♦♥ ♦ S

d ♦rt♠ ♥ ♠♦ t♦ ♦r ♥ X = S

d/GP s♥ t rsts r♦♠ t♦♥

• ♦rt♠ strts ♦♠♣t♥ ♥ t |GP |st ♦r♥ s♣ Sd ♥srt♥ |GP |

♦♣s ♣r ♥♣t ♣♦♥t

• ♥ t ♣r♦t♦♥ ♦ t rr♥t tr♥t♦♥ ♥r π s ♥♦ ②s ♦ ♥t t♦♥ t ♥ s♦♥ tt ♥ rtr ♣♦♥ts ♥♥♦t ♥tr♦ ②s ♦ ♥tt♦ t ♦rt♠ sts t♦ ♦♠♣t♥ ♥ X

♦t tt GP s ♥♦t t♦rs♦♥r t♥ t ♦rt♠ rtr♥s DT (GPP) ❲ ♥♦ ♦♠tr rtr♦♥ s♠r t♦ rtr♦♥ t♦ ♥ t♦ st t♦ ♦♠♣t♥♥ X ♦r t s ♦ t r ♣r♦t ♣♥ ❲ ♦ ♥♦t ♥r rtr♦♥

Page 101: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥② tr♥t♦♥s ♦ ♦tr s♣s

r ♣r♦t ♣♥

t G ♥♦t t r♦♣ ♥rt ② t s♦♠tr② tt ♠♣s ♣♦♥t ♦ S2 ♦♥t♦ ts ♥t♣♦

♣♦♥t ♦rt s♣ S2/G s t r ♣r♦t ♣♥ ❲ ♥ ♦r♠t t ♦♦♥

rtr♦♥

rtr♦♥ t rst s♣r s ♥ S2 tt ♦s ♥♦t ♦♥t♥ ♥② ♣♦♥t ♦

GP s ♠tr s♠r t♥ π/2 t♥ P ♥s t ♥② tr♥t♦♥ ♦ t r♣r♦t ♣♥ X/GPr♦♦ s ♣r♦♦ ♦♥t♥s t s♠ s s t ♣r♦♦ ♦ rtr♦♥ ♣t t♦ ts♣r s t rst ♠♣t② s♣r s s ♠tr s♠r t♥ π

2 t♥ t♦♥st ♥ t ♥② tr♥t♦♥ ♦ GP s s♦rtr t♥ π

2 ♥ ts ♣t ♦ t♦s s s♦rtr t♥ π ♥ ♥♥♦t ♦r♠ t♦② ♥ ♣r♦t ♦♥t♦ S

2/G

rtr♦♥ ♥ s ② t ♦rt♠ sr ♦ t♦ ♥ t♦ ♦♥rtt ♦♠♣t ♥② tr♥t♦♥ r♦♠ t st ♦r♥ s♣ S

2 t♦ S2/G

②♣r♦ s♣

r sss ♦ t♦ ①t♥ t ♣♣r♦ ♦ ♣tr t♦ ♦rt s♣s ♦ t ②♣r♦♣♥ ♥r t t♦♥ ♦ srt r♦♣ ♦ ②♣r♦ s♦♠trs ❲ rst s♦rt♥tr♦t♦♥ ♦♥ t ②♣r♦ ♣♥ H

2 ♥ ♦♥ ②♣r♦ ♥② tr♥t♦♥s ♥ sss r♦♣s ♦ ②♣r♦ s♦♠trs ♥ ①t♥ ♦r♠ ♥ ♦rt♠ t♦ ts stt♥ r♦♣s ♦ ②♣r♦ s♦♠trs tr♥ ♦t t♦ ♥♥t ♥ trt♦r② s ♠ rr t♥ ♦r r♦♣s ♦ ♥ s♦♠trs ❲ sss tr r♥t♣♣r♦s ♦r t s ♦ t r♦♣ ♦ t ♦ t♦rs

②♣r♦ ♣♥ H2

②♣r♦ ♣♥ s t ♣r♦♣rt② tt ♥ ♥ l ♥ ♣♦♥t p ♥♦t ♥ l tr r♥♥t② ♠♥② ♥s tr♦ p tt ♦ ♥♦t ♥trst l s r

r Pr ♥s ♥ t P♦♥ré s ♥s tr♦ t ♣♦♥t p r ♣r t♦l ❬♣❪

r r ♦r ♦♠♠♦♥ ♠♦s t♦ r♣rs♥t t ②♣r♦ ♣♥ t tr♠♥♦ t P♦♥ré s ♠♦ t P♦♥ré ♣♣r ♣♥ ♠♦ ♥ t ②♣r♦♦♠♦ ❬t❪ ❲ ♦♥② s t P♦♥ré s ♠♦ ♥ t ssq♥t sss♦♥s

Page 102: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

②♣r♦ s♣

♥ t P♦♥ré s ♠♦ ♣♦♥ts ♦ t ②♣r♦ ♣♥ r ♠♣♣ ♥s t♥ ♥t s ♣♦♥ts ♦♥ t ♥t r r ♣♦♥ts t ♥♥t② ②♣r♦ ♥s♦rrs♣♦♥ t♦ ♠trs ♦ t ♥t s ♦r rr rs tt ♥trst t ♥t r ♦rt♦♦♥② ②♣r♦ rs ♦rrs♣♦♥ t♦ ♥ rs t♦ tr ♥trs r

t② r ♥♦t ♥tr ♥ t ♦r♥ ♦ st♥ ♥t♦♥ s ♥ ② ds =2√

dx2+dy2

1−(x2+y2)

s t st♥ ♦ ♣♦♥t(xy

)t♦ t ♦r♥ s 2 tanh−1(

√x2 + y2)

r r ♦r t②♣s ♦ ②♣r♦ s♦♠trs t② ♥ rtr③ ② tr ①♣♦♥ts t ♥♥t② ②♣r♦ s♦♠tr② tt s ♥♦ ① ♣♦♥ts s r♦tt♦♥ ts ①t② ♦♥ ① ♣♦♥t t ♥♥t② t s ♠t r♦tt♦♥ ②♣r♦ tr♥st♦♥sr s♦♠trs t ①t② t♦ ① ♣♦♥ts t ♥♥t② s r t tr ♦r♥tt♦♥♣rsr♥ ②♣r♦ s♦♠trs ♦rt t②♣ ♦ ②♣r♦ s♦♠trs r t ♥♦♥♦r♥tt♦♥♣rsr♥ rt♦♥s ❬t❪ ❲ ♥♦ ♥tr♦ ②♣r♦ tr♥st♦♥s♥ ♠♦r t

t♦ ♣♦♥ts t ♥r♥t ② tr♥st♦♥ t ♥ ♥q ♦s ♥ t ②♣r♦♣♥ tr♥st♦♥ t tr♥sts ♣♦♥t ♦♥ ts ♥r♥t ♦s tr♥st♦♥t ♠♣s ♣♦♥t ♦ st♥ d t♦ t ♦s ♦♥t♦ ♥♦tr ♣♦♥t ♦♥ t qst♥t ♥ ♦st♥ d t♦ t ♦s s s t♦ t t tt t s ♥ s♦♠tr② st(p, q) =st(t(p), t(q)) ♦t tt p ♥ q ♦ ♥♦t t s♠ st♥ t♦ t ♥r♥t ♦st♥ t st♥ ② t② r tr♥st rs st(p, t(p)) 6= st(q, t(q)) ts t ♦sr ♣♦♥t p s t♦ t ♥r♥t ♦s t s♦rtr st♥ st(p, t(p)) ② t② r tr♥st s s ♥♠♥t r♥ t♦ t ♥ ♣♥ ♦r♥ strt♦♥ ♦ ②♣r♦ tr♥st♦♥s s r ♦r ♥st♥ ♥ s t t♦① ♣♦♥ts r ♥♦t ♥t♣♦ ♥♦t tt t st♥ ♦ ②♣r♦ tr♥st♦♥ ♦♥ t♥ ♦r s rr t♥ ♦♥ t ②♣r♦ ♦s

r t r♥st♦♥ ♦♥ ♠tr ♦ t P♦♥ré s t r♥st♦♥♦♥ ♥r ♦s

s ♦ss r ♥q ♥ t ②♣r♦ ♣♥ t ②♣r♦ ♦♥① ♦ ♣♦♥tst P ♥ ♥ ♥ t ss ② s t s♠st st S s tt t ♦st♥ t♦ ♣♦♥ts p ♥ q ♦ S s ♥tr② ♦♥t♥ ♥ S ♥ ②♣r♦ ♦r②♣r♦ tr♥ s t ♦♥① ♦ t♦ ♦r tr ♣♦♥ts ♥ H

2 rs♣t②♥ ❬❪ t t♦rs ♦♥sr ②♣r♦ ❱♦r♦♥♦ r♠s s♥ t ♣r♦♣rt② tt

♥ t P♦♥ré ♠♦s ②♣r♦ rs r ♥ rs ♥ ts ② t ♦rt♠♦r ♦♠♣t♥ t ♥ ♥② tr♥t♦♥ ♥ s rt② t♦ ♦♠♣t t

Page 103: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥② tr♥t♦♥s ♦ ♦tr s♣s

②♣r♦ ♥② tr♥t♦♥ s t ♠♣t② rs r ①t② t s♠ ♥ ♦tss

s♥ ♥ ♦ ❬❪ sr ♦ t♦ ♦♠♣t ②♣r♦ ❱♦r♦♥♦ r♠s s♥ t tr♠♥ ♠♦ r ♣♣r♦ s s t ♦r ♦ ❬❪ ♥ ①t♥ t♦ H

d ♦r♥tt♦♥♣rsr♥ srt r♦♣s ♦ s♦♠trs ♦♥ H

2 r s♥r♦♣s ❬t❪ ♥ ❲♥ ❬❲❪ sr s♦♠trs ♥ srt s♦♠tr② sr♦♣s♦ d♠♥s♦♥ ②♣r♦ s♣s

♦ t♦rs

r ♦♥② ♦♥sr t ♦ t♦rs s ♦♥ ♦ t ♠♦st s♠♣ ♦rt s♣s ♦♦♥st♥t ♥t rtr

❲ rst rqr s♦♠ ♠♦r ♥♦t♦♥s r♦♠ r♦♣ t♦r② t H r♦♣ ♥ H′ ♥♦t sr♦♣ ♦ H q♦t♥t r♦♣ H/H′ s t st ♦ ♦sts ♦ H′ ♥ H t t♣r♦t ♦ ssts s r♦♣ ♦♣rt♦♥ r♦♣ s s t♦ r r♦♣ ♠♥t♥ rtt♥ ♥ ♥q ② s ♣r♦t ♦ ♥rt♦rs ❲ ♥♦t t r r♦♣ t♥rt♦rs G ② < G > t R ♥♦t sst ♦ < G > st ♦ rt♦♥s q♦t♥t r♦♣ ♦ t r r♦♣ < G > ♥ t ♥♦r♠ sr♦♣ ♦ < G > ♥rt ②t rt♦♥s ♥ R s ♥♦t ② < G | R > s ♥♦tt♦♥ s r♦♣ ♣rs♥tt♦♥

♦ t♦rs ♥ ♥♦ ♦♥strt s ♥ ♦rt s♣ ♥r t t♦♥ ♦ r♦♣ ♥rt ② ♦r ②♣r♦ tr♥st♦♥s t a, b, c, ♥ d ♥♦t ♦r ②♣r♦tr♥st♦♥s ♥ a, b, c, ♥ d tr rs♣t ♥rs tr♥st♦♥s r r t st t♦r♦♣s t♥ ♦♥ H

2 tt ♥ ♦ t♦rs

G := < a, b, c, d | abcdabcd >

G′ := < a, b, c, d | ababcdcd >

r♦♣s G ♥ G′ r s♦♠♦r♣ t ♥♦t q ❬❪ s♦♠♦r♣s♠ ♥ ♦♥strt ♦♠tr② s♥ t ♦rt♠ sr ♥ ❬❱❨❪ ♦r ♠♦r sss♦♥s♦♥ ts s s♦ ❬ r❪

r ♦♥sr t r♦♣s ♦r t ♥♠♥t ♦♠♥ s t rr ♦t♦♥♥tr t t ♦r♥ ♥rt♦rs ♦ G ♥ G′ rs♣t② ♠♣ ♦t♦♥ s ♦♥t♦♦t♦♥ s s ♥ ♥tr♣rt s ♥t②♥ t s s s♦♥ ♥ r

♥rt♦rs ♦r G ♥ ♦s♥ s ♦♦s t a t ②♣r♦ tr♥st♦♥ tt

tr♥sts ♣♦♥ts ♦♥ t ♥ x①s ② 2 tanh−1(√

21+

√2

) t b, c, d t s♠

tr♥st♦♥s r♦tt ② π/4 ♥♠♥t ♦♠♥ ♦ G s t rr ♦t♦♥ t♥s ♦ π/4 ♦♥sr t t♥ ♦ t ②♣r♦ ♣♥ ② s ♦t♦♥s t rt① ♦ t t♥ t ♥♠♥t ♦♠♥s ♠t t♦ ♦♠♣t t ♥ ♦ 2π

❲ ♦ ♥♦t ♦♥sr t r♦♣ G′ r♦♣ G′ s t ♥t tt t s sr t♦s tt t ♥tt♦♥s t ♥s ♦♥ t ♦t♦♥ ② ♦ t♦rs ♦r ts♥rt♦rs r ♠♦r ♦♠♣t t♦ t

r♥t♦♥s ♦ t ♦ t♦rs

❲ rst ①t♥ ♦r♠ t♦ t s ♦ t ♦ t♦rs t P ♥t ♣♦♥t st ♥H

2 G t r♦♣ ♦ t ♦ t♦rs s ♥ ♥ t♦♥ H2/G t ♦rt s♣ t

♦r S, T ssts ♦ H ST := st | s ∈ S ♥ t ∈ T

Page 104: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

②♣r♦ s♣

r t ♥tt♦♥ s♠ ♦r r♦♣ G t ♥tt♦♥ s♠ ♦rr♦♣ G′

♣r♦t♦♥ ♠♣ π : H2 → H

2/G ♥ DT (GP) t ♥② tr♥t♦♥ ♦ H2 ♥

② t ♥♥t ♣r♦ ♣♦♥t st GP ♥ ♦r♠ ♥ ♦r♠t s ♦♦s♦r t ②♣r♦ s

♦r♠ t st♦♥ ♦ π(DT (GP)) ♦s ♥♦t ♦♥t♥ ②s ♦ ♥t ≤ 2t♥ π(DT (GP)) s tr♥t♦♥ ♦ X

♦♥② ♠ss♥ ♣rt ♥ t ♣r♦♦ ♦ ♦r♠ s t ♦ ♥t♥ss ♠♠ t ♦tr ♠♠s r ♣r② ♦♠♥t♦r ♥ ♦♥② r s♥ ♣r♦♣rts ♦ s♠♣s♥♣♥♥t ♦ tr ♠♥

❲ ♥♦ ♥r③ ♠♠

♠♠ st ♦ s♠♣s K tt s ♣ ♥ t ♥②♣r♦♣rt② t rs♣t t♦ GP s s♠♣ ♦♠♣① ♥ H

2

Pr♦♦ ♥ ♦rr t♦ s♦ tt K s s♠♣ ♦♠♣① t r♠♥s t♦ ♣r♦ tt ♦♥t♦♥ ♦ t s♠♣ ♦♠♣① ♥t♦♥ ♦ ♥t♥ss s ❲ s s♠rr♠♥tt♦♥ s ♥ t ♣r♦♦ ♦ ♠♠ s ♣

ss♠ tr s rt① v t ♥ ♥♥t ♥♠r ♦ ♥♥t s♠♣s ♥ ts ♥♥♥t ♥♠r ♦ ♥♥t s t tv ♥♦t t ②♣r♦ tr♥st♦♥ tt ♠♦s vt♦ t ♦r♥ ♥② ♣r♦♣rt② s ♥r♥t ♥r t t♦♥ ♦ s♦♠trs s♦ ♥♣♣② tv ♦♥t♦ K t♦t ♦s♥ t ♥② ♣r♦♣rt② s t♦t ♦ss ♦ ♥rt② ♥ ss♠ tt v s ♥ t ♦r♥ ♦rt ♦ v s ♣♦♥t st ♥ t ♠tr♦ t rst ♠♣t② s s ♦♥ ② t ♠tr ♦ t r♠sr♥ r ♦ t

♥♠♥t ♦t♦♥ s ∆ := 2 sinh−1

(√2(1+

√2)

sin(π/8)

)≈ 4.90 ♦ r♠sr♥

rs ♦ ②♣r♦ tr♥s tt r ♥♥t t♦ v ♥ ♣♦♥t ♥ t ♦rt ♦ ♣♦♥t ♥P ♦ st♥ rr t♥ ∆ r♦♠ v ♥♥♦t ♠♣t② s ♦ rs ∆ ♥tr t t♦r♥ s ♦♠♣t r♦♠ t t tt G s srt t ♦♦s tt t ♥♠r ♦ ♠♥ts♦ t ♦rt ♦ ♣♦♥t ♥ P tt ♥s ts s s ♥t ♥ P ts s ♥t t♦♦

❲ s♦♥ tt tr r ♦♥② ♥t② ♠♥② tr♥s ♥♥t t♦ v ♠♣srt② tt t ♥♠r ♦ s ♥♥t t♦ v s ♥t t♦♦

♥ t s♣s sss s♦ r ②s s ♦r♥ s♣s t♦ rs♦ tsss ♦ ♥♣t ♣♦♥t sts tt ♦ ♥♦t ♥ ♥② tr♥t♦♥ ♦ sss

Page 105: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥② tr♥t♦♥s ♦ ♦tr s♣s

② t s ♠ ♠♦r t ♥ ♦ ss ♥trst t♦ ♦♥strt ♦r♥ s♣s ♦ ②♣r♦♦rt s♣s ❲ ♣rs♥t t♦ tr♥t ♣♣r♦s

♦♠♣t t ♥t ♥♠r ♦ ♦♣s ♦ t ♥♠♥t ♦♠♥ ♦ t r♦♣ ♥♦♠♣t t ♥② tr♥t♦♥ ♦ H

2 ♥ ② ts ♥t st ♦ ♣♦♥ts

trt t ① ♥t ♣♦♥t st tt s r♥t t♦ ♥ ♥② tr♥t♦♥ ♦ t ♦rt s♣ ♥ r♠♦ ts ♣♦♥ts ♦♥② tr s♦♠ rtr♦♥ s♠r t♦rtr♦♥ s

♦r♥ s♣s

♦r♥ ♠♦tt♦♥ ♦r s♥ ♦r♥ s♣s ♦r ♦♠♣t♥ tr♥t♦♥s ♥ t tt♦rs s tt t ♦r♥ s♣s ♦ t t t♦rs r ♦♠♦♠♦r♣ t♦ t t t♦rs♥ s ♦♦s r♦♠ t ♠♥♥rt③ ♦r♠ ❬r❪ t X t♦♣♦♦s♣ ♥ X kst ♦r♥ s♣ χ(X) ♥♦ts t r rtrst ♦ s♣X t♥ t qt♦♥ χ(X) = k · χ(X) ♦s

tt t ♥s ♦ sr t ♥♠r ♦ ♥s s ♥ ② 1 − 12χ s

t r rtrst ♦ t t t♦rs s ③r♦ ♥② ♦r♥ s♣ ♦ t t t♦rs s♥ t t♦rs ♦ t♦rs s r rtrst −2 ♦♦♥② t rrtrst rss ♥ t ♥♠r ♦ sts ♥ t ♦r ♥rss s ♦rrs♣♦♥st♦ rr ♥♠r ♦ ♥s

♦ r♠♥t ♦♥ t ♥♠r ♦ ♥s ♥ s♦ ♥rst♦♦ ♥ ♠♦r♥tt ② t s ♦♥sr t♦♠♥s♦♥ t♦rs ♠ ♥ E

3 t♦rs st♦ ♥♦♥tr ♦♦♣s s ♦ ♦r♥ s♣ ♦rrs♣♦♥s t♦ ♦♥sr♥ rt♦rs t ♠♦r ♣♦♥ts ♦♥ t ♦ t ♥♦♥tr ♦♦♣s r ♦♥r ♥ t♦②s ♥ ttr♥t♦♥ ♥ ♦ ♣r♦ss ♦ ♥rt♥ t♦st ♦r♥ s♣ ♦t ♦ t♦rs ♦rrs♣♦♥s t♦ tt♥ ♦♥ ♥♦♥tr ♦♦♣ ♥ ♦t ♦ t♦r ♥ st ♦♣♥ s t♦ t ♦tr ♦ t♦rs s r ♥ ts ② ♦♥ ♥ s♥ ①♣♥ ♦♥ ♥♦♥tr ♦♦♣ s ♦♠ ♦♥r ♥ t ♦tr t♦ ♥sr ♥♥ ♥② rt s♣ s t♦ ♥s ♦ ♦r♥ ♦♦♣ ♥t ♥ ♦♥♥ ♦ ♦ ♦♦♣ ♥t ♦ ♥♦t t② ♥ t ♥♠r ♦ ♥s ts♠ ♦♦♣ ♥t s t ♦r♥ ♦ t t ♠t ♣♦ss t♦ t ♥ t ♦♦♣s ♥ ♠♦r ♦♠♣t ② ♥ ♦rr t♦ ♦ ♥tr♦♥ ♥ s♦rt ♦♦♣s

r ♦♥strt♥ t♦st ♦r♥ s♣ ♦ t ♦ t♦rs ❬❪

s t ♣♣rs t t♦ ♦♥strt ♦r♥ s♣ ♥ ②s ♦ ♥t t♦ ♥ ♦ t♦♥② t ♦r♥ ♠♦tt♦♥ ♦ s♥ ♦r♥ s♣s ♥♠② ttt② r t♦♣♦♦② q♥t t♦ t ♦r♥ s♣ s ♥♦t ♥ ♥②♠♦r

Page 106: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

②♣r♦ s♣

♦♣s ♦ t ♥♠♥t ♦♠♥ ♥ H2

t F ♥♦t t ♥♠♥t ♦♠♥ ♦ G ♥tr t t ♦r♥ ♥ P ⊂ F ♥t

♣♦♥t st ♠tr ♦ F s ∆ := 2 sinh−1

(√2(1+

√2)

sin(π/8)

)≈ 4.90 s t ♠tr

♦ t rst ♣♦ss ♠♣t② r t rs♣t t♦ GP ♦ tr ♥♥♦t ♥② s♦♥r t♥ ∆ ♥ t ♥② tr♥t♦♥ ♦ GP s ♣♦♥ts tt r rtr ②t♥ 3

2∆ r♦♠ t ♦r♥ ♦ ♥♦t ♥② ♥♥ ♦♥ t s♠♣s ♦ DT (GP) tt♥trst F ♦ t♦ ♦♥sr t sst G ♦ tr♥st♦♥s g ∈ G s tt gF♥ t s ♦ rs 3

2∆ ♥tr t t ♦r♥ ♥♦♥♠♣t② ♥trst♦♥ ❲ ♥ s♥s ♦rt♠ ♥ ♦rr t♦ ♥t② t st G ❬②♥❪ ❲ t♥ ♦♠♣t t ♥②tr♥t♦♥ ♦ H

2 ♥ ② t ♣♦♥t st GP ♥ ①trt s♠♣s tt ♥trstF Pr♠♥r② st♠t♦♥s s♦ tt t ♥♠r ♦ ♥♠♥t ♦♠♥s t♦ ♦♥srs r ♦ s ts ♣♣r♦ tr♥s ♦t t♦ ♥♦t r② ♣rt

♥♦tr s t♦ ♥r③ t rst ♦ ❬❪ tt sr ♥ t♦♥ t♦ t ②♣r♦ ♣♥ ❯♥♦rt♥t② ♥♦s s♠s ♦ ♥♦t ①t♥ t♦ t ②♣r♦s rtss ♥ ♥ st tt s ♥♦♦s t♦ F (n) ♥ ②♣r♦ s♣ tF

(1)p ♥♦t t ❱♦r♦♥♦ ♦ p ♥ t ②♣r♦ ❱♦r♦♥♦ r♠ ♦ Gp ♥ F

(1)p s

♥♠♥t ♦♠♥ ♦ G ♦ ♥ F(n)p :=

⋃q∈Fp

F(n−1)q

♦r♠ t τ s♠♣① ♥ DT (GP) t t st ♦♥ rt① ♥ F(1)p ♥ τ

s ♦♠♣t② ♦♥t♥ ♥s F(3)p

Pr♦♦ ♣r♦♦ ♦rs ♥ t s♠ ② s t ♣r♦♦ ♦ ♠♠ ♥ ❬❪ t σ♥ τ ♥♦t s♠♣s ♥ DT (GP) s tt σ s p s ♦♥ ♦ ts rts ♥ τ s t

st ♦♥ rt① ♥ F(1)p

F(1)p ♦♥t♥s t ♥tr cσ ♦ t r♠sr♥ r ♦ σ s r s s

t♦ t ♦♥strt♦♥ ♦ F(1)p s ❱♦r♦♥♦ cσ s ♦ts ♦ F

(1)p t♥

♣♦♥t ♥ t ♦rt ♦ p ♦ ♦sr t♦ cσ t♥ p s ♦♥trt♦♥ t♦ tt tt cσ s t r♠♥tr ♦ s♠♣① t p s rt①

σ ⊂ F(2)p ♦t tt r♦♠ t ♥t♦♥ ♦ F

(1)p ♦♦s tt cσ ∈ F

(1)p t♥

p ∈ F(1)cσ ♥ s♦ σ ⊂ F

(1)cσ ⊂ F

(2)p ② ♥t♦♥ ♦ F

(2)p

t q ∈ F(1)p rt① ♦ τ r♦♠ t ♦ r♠♥tt♦♥ ♥♦ tt τ ⊂ F

(2)q

♥ ② ♥t♦♥ ♦ F(3)p t ♥s♦♥ F

(2)q ⊂ F

(3)p ♥ ts τ ⊂ F

(3)p ♦s

♥ ♦rr t♦ ♦r♠t rtr♦♥ t♦ tr ♣♦♥t st ♥s ♥②tr♥t♦♥ ♦ t ♦ t♦rs ♥ s♠r ♣♣r♦ s ♦r t t t♦rs

rtr♦♥ t ♠tr ♦ t rst r♠sr♥ r ♦ t tr♥s ♦ t

♥② tr♥t♦♥ ♦ GP∩F(3)p tt ♥trst F

(1)p s s♦rtr t♥ tanh−1

(√2

1+√

2

)≈

1.53 t♥ ♥② ♣♦♥t st Q t P ⊆ Q ♥s ♥② tr♥t♦♥ ♦ t ♦ t♦rs

Page 107: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥② tr♥t♦♥s ♦ ♦tr s♣s

r cσ s ♥ F(1)p

Pr♦♦ r♦♠ t♦♥ ♥♦ tt t s♦rtst st♥ ② ♣♦♥t ♥

tr♥st ♥r G s t st 2 tanh−1(√

21+

√2

)≈ 3.06 ♦ r♠sr♥ rs ♦

tr♥s tt ♥trst F(1)p r s♦rtr t♥ ts ♦♥st♥t t♥ tr ♥♥♦t ②s

♦ ♥t t♦ ♥ tr ♥ ♥ ♣♦♥ts ♥ ts Q ♥s ♥② tr♥t♦♥♦ t ♦ t♦rs ♦r♥ t♦ ♦r♠

♦rt♠ srs ♦ t♦ ♦♠♣t ♥② tr♥t♦♥s ♦ t ♦ t♦rs ♣♦ss

♦rt♠ ♦♠♣t ♥② tr♥t♦♥ ♦ H2/G ♥ ② t ♣♦♥t st P

♥♣t t P ♦ ♣♦♥ts ♥ F(1)0

t♣t π(DT (GP)) t s tr♥t♦♥ ∅ ♦trs P ′ ⇐ P P♦♣ p r♦♠ P ′

P ⇐ p H ⇐ DT (GP ∩ F

(3)0 )

t ♦♥st ♥ H ∩ F(1)0 s ♦♥r t♥ tanh−1

(√2

1+√

2

)♦

P♦♣ p r♦♠ P ′ P ⇐ P ∪ p ♦r p′ ∈ Gp ∩ F

(3)0 ♦

♥srt p′ ♥t♦ H

♥ ♦r H = DT (GP ∩ F(3)0 )

P ′ = ∅ π(DT (GQ)) s tr♥t♦♥ ♦r ♥② Q ⊇ P t♥ ♦t♦ s ①t

♦♠♣t π(DT (GP)) r♦♠ H st t♦ ♦ t♦rs

♥srt ♣♦♥ts r♠♥♥ ♥ P ′ ♥t♦ π(DT (GP)) ♦♥ ② ♦♥ rtr♥ π(DT (GP))

♦rrt♥ss ♦ t ♦rt♠ ♦♦s r♦♠ ♦r♠s ♥ s srtr♦♥ ♥ s t ♥♣t st P ♦s ♥♦t ♥ ♥② tr♥t♦♥ ♦ H

2/G

Page 108: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

②♣r♦ s♣

tr r t② sr ♦♣t♦♥s ♣♦ss ♦r s♠♣t② ♦s t♦ rtr♥ ♥♦t♥ ♥♥ t ♠♣♠♥tt♦♥ t ♦ ♦ ♥trst t♦ rtr♥ t rr♥t strtr H t♦ s♦ ♣♦ss t♦ rtr♥ t s♠♣s r♦♠ H tt ♥trst F

(1)0 s tr ♠s

♥r π ♦r♠ ♣rtt♦♥ ♦ H2/G ♦r♥ t♦ ♦r♠

♠♥ t② s t♦ t② ♦♠♣t t ♣♦♥t st PG ∩ F(3)0 ♥ s

♣♣r♦ s t♦ ♦♠♣t t st G ♦ s♦♠trs ♥ G s tt GF(1)0 ⊇ F

(3)0 ❲

♥♦t ♦♥ ts ♦♠♣tt♦♥ t ♥ s♠♣ ♦r ♦♥ ♦♥ t r♥t② ♦ G❲ ♦♥sr t ♣rtt♦♥ ♦ t ②♣r♦ ♣♥ ♥t♦ ②♣r♦ ♦t♦♥s ♥ ② GF

(1)0

♦♥sr t ♠♥ts ♦ G tt ♠♣ F(1)p t♦ ♦♥ ♦ ts ♥♦rs ♥ t ♦t♦♥ ♣rtt♦♥

♦ H2 sr ♦ ♥♦♥ ♦ F

(1)0 ♥ ts ♥♦rs r② ♦r♠s sst ♦

F(3)p r s ♦♥ ♥♦r ♣r t ♥ ♠♦r ♥♦rs ♣r rt①

♦tr t t ♦r♥ ♦♣② F(1)p ts ♠s 1 + 8 + 40 = 49 ♦♣s t♦ ♦♥sr ♥

tt t ♥♠r ♦ ♦♣s s ♦♥② ♦r ♦♥ ♦♥ t rqr ♥♠r ♦ ♦♣s t♦♦♥sr ts ♣♣r♦ ♦s ♥♦t s♠ t♦ r② s ♥ ♣rt

♣♣r♦ sr ♦ s ♥rtss ♥ s t s ①t♥s t♦ ♦trsrt r♦♣s ♦r GP ∩ F

(3)0 ♥ ♦♠♣t

♠♠② ♣♦♥t st

♥ ts ♣♣r♦ strt t ♥ ♥t tr♥t♦♥ ♦ ♣♦♥t st PD tt s ♦s♥s tt ♥② ♣♦♥t st tt ♦♥t♥s PD ♥s ♥② tr♥t♦♥ ♦ H

2/G ss t s♠ ♣♣r♦ s sr ♥ t♦♥ ♦r t s ♦ t t t♦rs t♥♣t ♣♦♥t st ts ♥s ♥② tr♥t♦♥ t ♣♦♥ts ♦ PD ♥ r♠♦r♦♠ t tr♥t♦♥

t P ♣♦♥t st s tt PD ⊆ P ❲ ♥t t♦ ♣r♦ tt π(DT (GPD)) s ♥② tr♥t♦♥ ♦ H

2/G t s s♥t t♦ s♦ tt t rstrt♦♥ ♦ π ♦♥ t♦♥♦♥s♦♥t ss tt r ♠♣t② t rs♣t t♦ GPD s ♥t s ♠♣s tt trstrt♦♥ ♦ π ♦♥ ♥② t♦ ♠♣t② ss ♥ GP s ♥t t♦♦ ♥ tr ♥♥♦t ②s ♦ ♥t t♦ ♥ ts π(DT (GP)) s ♥② tr♥t♦♥ ♦ H

2/G ♦r♥t♦ ♦r♠

❲ ♣r♦♣♦s ♣♦♥t st PD ♦ ♣♦♥ts ♥ r ♣♦♥ts ♥s t ♥♠♥t♦♠♥ ♦♥ t ♦rr ♥ ♥ t ♦r♥r s ②♣r♦ r♠rs r ♥r♠rs t ♥ s♦♥ tt π(DT (P ∪ PD)) s ♥② tr♥t♦♥ ♦ H

2/Gs ♣♣r♦ ♣♣rs t♦ t ♠♦st ♣rt ♠♦♥ t ♣rs♥t ♦♥s r

s tt t ♥♣t ♣♦♥t st ♦s ♥♦t ♥ ♥② tr♥t♦♥ ♦ H2/G t

♥② tr♥t♦♥ ♥ ② ♠♦ ♥♣t ♣♦♥t st s rtr♥ s ♣♣r♦♥r③s t♦ ♦tr r♦♣s ♥ ♣♣r♦♣rt ♠♠② ♣♦♥t st ♥ ♥

sss♦♥

❲ ♣rs♥t tr ♣♣r♦s t♦ ♥ ss ♥ t ♥♣t ♣♦♥t st ♦s ♥♦t♥ ♥② tr♥t♦♥ ♦ t ♦ t♦rs ♥ t ②♣r♦ s t ♠♦tt♦♥♦r s♥ ♦r♥ s♣s s ♦♥ ♥ t s ♦ ♥ ♦r s♣r s♣s s ♥♦t ♥♥②♠♦r ♦r♥ s♣s r ♥♦t ♦♠♦♠♦r♣ t♦ t ♦r♥ s♣ s ♥ t t t♦rs♥ t ♥rs ♦r♥ s♣ s ♥♦t ♥t s ♥ s♣r ♦rt s♣s ♦ t ♥tr♣♣r♦ ♦ t♦ ♦♠♣t ♥ H

2 s♥ s ♠♥② ♦♣s ♦ t ♥♣t ♣♦♥t st s

Page 109: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♥② tr♥t♦♥s ♦ ♦tr s♣s

r Pr♦♣♦s ♠♠② ♣♦♥t st PD ♦ ♣♦♥ts ♦r t ♦ t♦rs

♥ssr② t♦ ①trt sst ♦ t tr♥t♦♥ ♦♥t♦ t ♥tt♦♥s ♥ ②t r♦♣ G ♥ ♣♣ s s ♣♦ss ♥ t♦ t ♥♠r ♦ rqr ♦♣str♥s ♦t t♦ r② r ♥ ♥② ♥st ♦ ♥♥ t s♣ ♣rs♥t ♥♣♣r♦ tt ♠♦s t ♣♦♥t st s ♣♣r♦ s r② ♣rt ♥ s t ♥t♥♣♣t♦♥ ♥ ♦♣ t ①tr ♣♦♥ts ♥ s ♦ s♠ ♦r ② strt ♥♣t ♣♦♥tsts

Page 110: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♣tr

♦♥s♦♥ ♥ tr ♦r

❲ ♣rs♥t ♥ ♣♣r♦ t♦ ♦♠♣t t ♥② tr♥t♦♥ ♦ T3c ♥ ②

♥ ♣♦♥t st P ♦♣ ♦rt♠ s ♠♣♠♥t ♥ s tr♦t ♦♣♥ s♦r rr② ①t♥s♦♥s ♥ ♣tt♦♥s ♦ ts ♣♣r♦ t♦ ♦tr t♥ s♣r ♦rt s♣s ♥ t♦ t ♦ t♦rs ♦ ♦♥st♥t ♥t rtr rsss r♥ t ♦rs ♦ ts ♦r s♦♠ ♠♦r ♥trst♥ qst♦♥s r♦s ♣rs♥t ♥ ts ♣tr

strt♦♥ t♦ s♠♣ ♦♠♣①s

♥ ts ♦r ♦♥♥trt ♦♥ ♦♠♣t♥ s♠♣ ♦♠♣①s ♦t ♦r t ♣r♣♦s ♦♠t♠t s♦♥♥ss ♦ t ♥t♦♥ ♦ t ♥② tr♥t♦♥s s s ♦r ♣rt ♦♥srt♦♥s ♥ t ♠♣♠♥tt♦♥ s s♦ t♦♥ rtss t♠t ♥trst♥ t♦ ♦♥sr tsst♦♥s tt t ♥② ♣r♦♣rt② t r ♥♦ts♠♣ ♦♠♣①s ♥♦t tr♥t♦♥s r r② sss t ♣r♦♠s rs♥♥ ♦♠♣t♥ t strtrs ♦tr t♥ s♠♣ ♦♠♣①s

① s♠♣ ♦♠♣①s

❲ ♦ r① ♦♥t♦♥ ♦ t s♠♣ ♦♠♣① ♥t♦♥ t♦ t ♦♦♥ t σ ♥ σ′ s♠♣s ♥ K ♥ t ♥trst♦♥ σ ∩σ′ s st ♦ s♠♣s ♥ K st♦♥ ♦ ts r① s♠♣ ♦♠♣① ♦ ♥♦♥tr ②s ♦ ♥tt♦ t ♥♦t ♦ ♥t ♦♥ ♦ ♦♥trt t s♠♣① ♥t♦♥ ♦t ♦♥st♥ts ♦♥ t ♥♠r ♦ rqr ♦♣s ♥ t ♥t ♦ ♠♣r♦s r t s♠s s t♦ s♥ ♥ ♥t t strtr ♦r r① s♠♣ ♦♠♣①s s♦ ts ♣♣r♦ ♠t ♥ ♥trst♥ rt♦♥ ♦r rtr ①♠♥t♦♥♥ sr r s tt ♦rt♠s tt rqr t t strtr t♦ s♠♣♦♠♣① ♠st ♠♦ ♦r♥② ♦r ♥st♥ ♥srt♥ ♥ ♣♦♥t t♦ t tr♥t♦♥ s♥ t str♦ ♣♣r♦ s sr ♥ t♦♥ rqrs t ♦ t♦ ♦♠♦♠♦r♣ t♦ d ① s♠♣ ♦♠♣①s ♦ ♥♦t ts ♣r♦♣rt②

∆♦♠♣①s

tr ♣rs♥ts ❲♦♠♣①s rst ♥tr♦ ② ❲t ♥ ♥ srs ♠♦r rstrt t②♣ ♦ ♦♠♣①s t s♦ ∆♦♠♣①s ❬t❪ ♥ t ∆♦♠♣①t s♠♣s r r♣rs♥t ② ♠♣s tt r ♥♦t ♥ssr② ♥t ♦♥ t s♠♣①

Page 111: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♦♥s♦♥ ♥ tr ♦r

r r① s♠♣ ♦♠♣① ♥ T2 tt s t ♥② ♣r♦♣rt②

♦♥rs tr ♥ s♦♦♣s ♥ ts ② T2 ♥ tsst ② t♦ tr♥s

tr s ♥ ♦♥ rt① ♦r t s ♥♦t sr ♦ t strtr st♦r♥ ∆♦♠♣①s ♦ ♠♣♠♥t r s ♦♥♦♥ ♦r ♦♥ ts t♦♣ ② ♦♥ ❱rèr♥ ❬❱❪

strt♦♥s ♦♥ s♣s

r rr♥t ♣♣r♦ s s♦♠ r ♠tt♦♥s ♦♥ t t②♣s ♦ s♣s t ♥ ♥ r ①♣♦r t rs♦♥s ♦ ts rstrt♦♥s ♥ tr② t♦ ♦♣ s ♦ t♦ ♥ sss

❯♥♦♥ ♥♠♥t ♦♠♥s ♥ t♦♥ ♦♥sr ♦♥② r♦♣s t♦♥ ♥♠♥t ♦♠♥ s♦ t r♦♣s ♦ t♦♥ ♥♥ t t t♦rs ♥ t♦ t♦rs s s r♦♣s ♦ s♦♠trs ♦♥ t s♣r ♦♥ ♥♠♥t♦♠♥s

♥ ①♠♣ ♦ r♦♣ t ♥ ♥♦♥ ♥♠♥t ♦♠♥ s t r♦♣ GC ♥rt ② ♦♥ tr♥st♦♥ t♥ ♦♥ E

2 q♦t♥t s♣ E2/GC s t ②♥r t s

ss♠ tt GC s ♥rt ② t ♥t tr♥st♦♥ ♦♥ t x①s t P ♣♦♥t st♥ E

2 t♥ DT (GCP) t ♥② tr♥t♦♥ ♦ E2 ♥ ② GCP s t ♦♦♥

♣r♦♣rts

t pmax t ♣♦♥t ♥ P t rst y♦♦r♥t t t ∈ GC ♦♥ ♦ t♥rt♥ ♥t tr♥st♦♥s ♥ tr s ♥ t♥ pmax ♥ tpmax ♥DT (GCP)

♥♦♥ ♦ s♠♣s ♥ DT (GCP) s t ♦♥① ♦ GCP s ♥♦t qt♦ E

2 ♣♦♥ts ♦ rr y t♥ pmax ♦ ♥♦t ♥ t ♦♥①

❲♥ ♣r♦t♥ DT (GCP) ♦♥t♦ E2/GC t rst ♣r♦♣rt② ♠♣s tt tr s s

♦♦♣ ♥ pmax ♦♦♥② t st trst ♦r♥ s♣ s ♥ssr② t♦ ♦②s ♦ ♥t t♦ ♥♣♥♥t ♦ t ♣♦♥t st P s r

s♦♥ ♣r♦♣rt② ♠♣s tt t ♣r♦t tr♥t♦♥ s ♥♦t tr♥t♦♥ ♦ ②♥r t ♦♥② ♦ ♥ ♥♥s s ②s ♣r♦♠ ♦r t ♠♣♠♥tt♦♥ s trr♥t ♠♣♠♥tt♦♥ ♥♥♦t ♥ s♣s t ♦♥rs ♥ t s ♦ E

2

♥ E3 rt① t ♥♥t② s ♥ ♥tr♦ ♥ ♦rr t♦ r♣rs♥t tr♥t♦♥ ♦ t

♦♥ ♣♦♥t ♦♠♣tt♦♥s E2 ∪ ∞ ♥ E

2 ∪ ∞ rs♣t② s t♦♥ s

Page 112: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

②♣r♦ ♦rt s♣s

r ♥② tr♥t♦♥ ♦ GCP

s ♥♦t ♣♦ss ♦r t ②♥r s t s t♦ ♦♥rs ♥ rt① t ♥♥t② ♦ ♣rt ♦ ♣ ♦♥ ♦t ♦♥rs s ts ♥♦r♦♦ ♦ ♥♦t ♦♠♦♠♦r♣t♦ E

2 ♥ s♦ E2/GC ∪ ∞ ♦ ♥♦t ♠♥♦ ♦♣t♦♥ ♦ ♥ t♦ r♥trts t ♥♥t② ♦♥ ♦r t ♣♣r ♣ ♥ ♦♥ ♦r t ♦r ♣ s ♠♦r t t♦♥ ♥ tr♠s ♦ ♠♣♠♥tt♦♥

♥ tr ♠♥s♦♥s tr r t♦ r♥t t②♣s ♦ ②♥rs ♦rt s♣s E3/GC

♥ E3/G2C r G2C ♥♦ts t r♦♣ ♥rt ② t♦ r♥t ♥t tr♥st♦♥s

E3/GC s s♣ tt s ♣r♦ ♦♥ ♦♥ ①s E

3/G2C s ♣r♦ ♦♥ t♦ ①s ♦r♦t s♣s ♣rt ♣♣t♦♥s ①st s ❬r❪ s♦ ts s♦ ♥ ♥trst♥rt♦♥ ♦ rsr t♦ ♣rs

♠♦r ♥r ♦r♠t♦♥ ♦ t ♣r♦♠ ♦ ♦♥sr ♦rt s♣s ♦ Ed ♥r

t t♦♥ ♦ r r♦♣ ♦ ♠♥s♦♥ s♠r t♥ d

②♣r♦ ♦rt s♣s

❯♥ ♦r t s ♦ t ♥ s♣r ♦rt s♣s ♦ ♥♦t ②t ♥r ♣♣r♦♦r ②♣r♦ ♦rt s♣s ♥ t♦♥ s♦♠ ♣♣r♦s ♦r t ♦ t♦rstt r ①♣t t♦ ①t♥ t♦ ♦tr ♦rt s♣s ♦ H

2 ♥ ♥ ♦ Hd ♦r s t

ss ♦ srt r♦♣s ♦ ②♣r♦ s♦♠trs s ♠ rr t♥ ♦r t t ♦r ts♣r s tr r st ♠♥② ♦♣♥ qst♦♥s ♦♥ ts t♦♣ ♥ ♥①t st♣ t ♦ s t♦ ①t♥ ♦r ♥♥s t♦ srs ♦ r ♥s ♥♦tr t♦♣ t♦ ①♠♥ s♦rt s♣s ♦ r♠♥s♦♥ ②♣r♦ s♣s

Page 113: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♦♥s♦♥ ♥ tr ♦r

Page 114: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

♦r♣②

❬❪ ♥ ♠♥t ♦♠♥q tt ♥ r rs ♦♠♣①t② ♦ ♥② tr♥t♦♥ ♦r ♣♦♥ts ♦♥ ♦r♠♥s♦♥ ♣♦②r ♥ Pr♦♥s♦ t t ②♠♣♦s♠ ♦♥ srt ♦rt♠s ♣s

❬❪ r ♥ ♦♦♠♦♥② Pr♦ ♦rts ♦♥ t rr ②♣r♦♦t♦♥ P②s

❬s❪ r s♣♦ ♦♠♣t♥ ♦♠♦♦② ♦ s♦♠♣①s ♦ t t♦rstt♣sr♣ts♥♦r♥sr♣ts❲s♥

♦rs♣♦r❴s♣♦❴❲❴♣

❬❪ ♥ ♠♥t ♥ ♦ ♥ ü♥tr ♦t ♥r♠♥t ♦♥strt♦♥s♦♥ ♥ Pr♦♥s ♦ t t ♥♥ ②♠♣♦s♠ ♦♥ ♦♠♣tt♦♥♦♠tr② ♣s

❬❪ r♥③ r♥♠♠r ♥ ♦ ♥ ❱♦r♦♥♦ r♠s ♥ örür ♥ ♦r ❯rrt t♦rs ♥♦♦ ♦ ♦♠♣tt♦♥ ♦♠tr②♣s sr ♥ Psrs ❱ ♦rt♦♥ ♠str♠

❬❪ ①♥r♦ ♦ t♦rs strt♦♥ tt♣♥♣♦r

♦❴t♦rs❴strt♦♥♣♥

❬r♠❪ r r♠str♦♥ s ♦♣♦♦② ♣r♥r❱r

❬❪ r ♥♥② ♥ ♦♥q r♥t♥ t r ♣r♦t♣♥ ♥t♠t s♣ts ♦ ♦♠♣tr ♥ ♥♦r♠t♦♥ ♥s

❬r❪ r♥③ r♥♠♠r ❱♦r♦♥♦ r♠s sr② ♦ ♥♠♥t ♦♠tr t strtr ♦♠♣t♥ r②s ♣t♠r

❬s❪ tt str♥ ♥r Pr♦r♠♠♥ ♥ t ❯s♥ ♥ ①t♥♥ t t♥r ♠♣t rr② s♦♥❲s② ♦♥♠♥Ps♥ ♦ ♥ ♦st♦♥ ❯

❬P❪ ré rö♥♥♠♥♥ rst♦♣ r♥ ♥ ②♥ P♦♥ ♥tr rt♠t ②s ♥t ②♥♠ trs ♦r ♦♠♣tt♦♥ ♦♠tr② srt♣♣ t♠ts

Page 115: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

P❨

❬❪ ♥♥ ♦ss♦♥♥t r rs ♥ ♠ ♦r♥s ♥r♠♥t♦♥strt♦♥ ♦ t ♥② r♣ ♥ ♠♠ ♠♥s♦♥ ♥ Pr♦♥s♦ t t ♥♥ ②♠♣♦s♠ ♦♥ ♦♠♣tt♦♥ ♦♠tr② ♣s

❬r❪ r♥r ♦♠♣tt♦♥ strtr ♦♦② Pr♦ tr♥t♦♥s ♦r ♠♦r ②♥♠s tt♣s♦♣♥rr♦♠tr

♦♦rt♦♥sr♣r♦r♠t♠

❬❨❪ rs r♥ ♣♣st♥ ♥ r♥s ❨♦ ①♣t ①tr♠s ♥ ♥② tr♥t♦♥ ♥tr♥t♦♥ ♦r♥ ♦ ♦♠♣tt♦♥ ♦♠tr②♥ ♣♣t♦♥s

❬❪ r Ür ♥sr♣♣♥ s n♠♥s♦♥♥ s♥ ♠s ♠t ♥♠ ♥♥ ♥♠♥tr ött♥rrt♥

❬❪ ♦r♦ ♥ ♦ st ♥② tr♥t♦♥s ♥ tr ♠♥s♦♥s ♦♠♣tr t♦s ♥ ♣♣ ♥s ♥ ♥♥r♥ ♠r

❬P❪ ♦ ②♥ ♦t ♥ ♦♥ P♦rt r♠♥s♦♥ ♦r♦s♥ tr ♦♠tr strtrs ♦été ♠té♠tq r♥ Prs

❬❪ ♥♥ ♦ss♦♥♥t ♥ t ♦t Pr♦② ♦♦ s♠♣♥ ♥♠s♥ ♦ srs r♣ ♦s

❬♦❪ r♥ ♦②r ♦♠♣t♥ rt tsst♦♥s ♦♠♣tr ♦r♥

❬❪ ♥ ♥ ♦♥strt♥ ♥② tr♥t♦♥s ♦♥ s♣♥rs ♥ r♦♣♥ ②♠♣♦s♠ ♦♥ ♦rt♠s ♦♠ ♦ tr♦ts ♥ ♦♠♣tr ♥ ♣s

❬❨❪ ♥♥ ♦ss♦♥♥t ♥ rtt ❨♥ ♦rt♠ ♦♠tr② ♠r ❯♥rst② Prss ❯ r♥st ② ré rö♥♥♠♥♥

❬♠❪ ♥ q ♠♣②♦ ❱♦r♦♥♦ ♣rt ②♥♠s tt♣s♦♣♥rr♦♠tr♦♦rt♦♥sr

♣r♦r♠t♠

❬+❪ ♥ r♦ Pr♦ str♦ ést♥ ♦r♦t r ♦r♦♥q ♥ ♠ ❲♦r♠sr ♦st ♥ ♥t ♥② tr♥t♦♥s ♦ ♣♦♥ts ♦♥ ♦r ♦s t♦ s♣r ♥ t ♥tr♥t♦♥ ②♠♣♦s♠♦♥ ①♣r♠♥t ♦rt♠s ♦♠ ♦ tr ♦ts ♥ ♦♠♣tr ♥ ♣s

❬❪ ❲♥ ♥ ♠ ② ♥ ♦s ♥ ♣rt ♥②♠s♥ ♦rt♠ ♦r r ss ♦ ♦♠♥s ♥ Pr♦♥s ♦ t t♥tr♥t♦♥ s♥ ♦♥t ♣s

Page 116: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both

P❨

❬❪ ♥ r♦ ❱ssr♦♥ s♦♣♦♦s ♥ ♦♥q s♥ ♦tr♣②♣r♦ srs ♥ P♦str ♣rs♥tt♦♥ t ♥tr♥t♦♥ ♦♥r♥ ♦♥ rs ♥ rs

❬❪ ♦♠♣tt♦♥ ♦♠tr② ♦rt♠s rr② tt♣♦r

❬❪ P r♥tqt② ♠s ♥rt♦♥ ♦r r srs♥ Pr♦♥s ♦ t t ♥♥ ②♠♣♦s♠ ♦♥ ♦♠♣tt♦♥ ♦♠tr②♣s

❬❪ ♥ r♦ ♦ rt♦ ♥ ♦♥q ♦♣♥ t tr♥t♦♥s r♦♠ t ♥r②♥ s♣ ♥ ❲♦rs♦♣ ♦♥ ♦rt♠♥♥r♥ ♥ ①♣r♠♥ts ♣s

❬❪ ♦①tr ♥ ❲ ♦sr ♥rt♦rs ♥ t♦♥s ♦r srtr♦♣s ♣r♥r❱r r♥ r ❨♦r ♦②♦

❬♦①❪ ♦①tr r ♦♠♣① P♦②t♦♣s ♠r ❯♥rst② Prss♠r ♥♥ ♥ t♦♥

❬❪ ♥♥t rs♦♥ ♥ Ptr ❲ ♦r ♦rt♠s ♦r ♠tr ♣rs ♥♦♥① s tt r ♦♣t♠ r♥♦♠③ ♥ ♥r♠♥t ♥ Pr♦♥s♦ t t ♥♥ ②♠♣♦s♠ ♦♥ ♦♠♣tt♦♥ ♦♠tr② ♣s

❬❪ ♥ r♦ ♥ ♦♥q ❱♦ ♥ t ♦♠♣tt♦♥ ♦ ♣r♦ tr♥t♦♥s ♥ Pr♦♥s ♦ t t ♥♥ ②♠♣♦s♠ ♦♥♦♠♣tt♦♥ ♦♠tr② ♣s

❬❪ r r r ♥ r r r♠rs ♥ tr r③♦♣♦♠♣tt♦♥ ♦♠tr② ♦rt♠s ♥ ♣♣t♦♥s ♣r♥r❱rr♥ r♠♥② ♥ t♦♥

❬❪ ♥r♦ Prã♦ ♦ r♠♦ ♠♥♥♥ ♦♠tr② räsr ♦st♦♥

❬❪ ♦s ♥♦ ♥ rrt sr♥♥r ♥ ♥r♠♥t ♦rt♠♦r tt ♥♠rs ♦ s♠♣ ♦♠♣①s ♦♥ t s♣r ♦♠♣tr ♦♠tr s♥

❬❪ ♥ r ♠♥♥♦ ♥ ♦♥r♥ ♦ t ♦② ♦rt♠ ♦r ♦♠♣t♥ ♥tr♦ ❱♦r♦♥♦ tsst♦♥s ♦r♥ ♦♥♠r ♥②ss

❬❪ ♦rs ♥② r s♣èr ③st ♠ t♥t♠ts stst♥♥②

❬❪ rst♦♣ ♣t s♦rt♥ ♥ ❯sr ♥ r♥ ♥ t♦r ♦r t♦♥ tt♣♦r♥

tst♦❴t♠❴♠♥♣st♠P♣t♦rt♥

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❬❪ r rs ♥② rr② ♥tr♥t♦♥ ♦r♥ ♦ ♦♥t♦♥s ♦ ♦♠♣tr ♥

❬❪ ♥♥ rts ♥ Ptr ❱ ♦♥② ②♥♠ ♦♠tr② ♦r ♠ts ss♣t ♣rt ②♥♠s tt♣①①①♥♦s♦♥♠t

❬❪ ♦ rrs ♥ ♥ s♦♥ r♦ tr♥t♦♥s ♥r②st♦r♣ r♦♣s Pr♦ t♠t ♥r

❬❪ ♦ P ♦♥ ♥ ♥ s♦♥ Pr♦ ♦♥ t♥s Pr♦t♠t ♥r

❬❪ rs sr ♥ ② ②♥♠ ♥② tr♥t♦♥ ♥ ♦rt♠ ①♣t t♠ ♣r ♦♣rt♦♥ ♦♠♣tt♦♥ ♦♠tr②♦r② ♥ ♣♣t♦♥s

❬❪ r rs t♥ sr ♥ ♦♥q s♣ ♦ s♣rs ♦♠tr t♦♦ t♦ ♥② t② rsts ♦♥ ❱♦r♦♥♦ r♠s ♥ Pr♦♥s♦ t t ♥♥ ♦♥r♥ ♦♥ ♦♠♣tt♦♥ ♦♠tr② ♣s rs♦♥ s sr ♣♦rt tt♣♥rr♥r

❬P❪ r rs ♥ ②♥ P♦♥ ♥t ①t ♦♠tr ♣rts ♦r♥② tr♥t♦♥s ♥ Pr♦♥s ♦ t t ❲♦rs♦♣ ♦♥ ♦rt♠♥♥r♥ ♥ ①♣r♠♥ts ♣s

❬P❪ r rs ②♥ P♦♥ ♥ ♦♥q ❲♥ ♥ tr♥t♦♥ ♥tr♥t♦♥ ♦r♥ ♦ ♦♥t♦♥s ♦ ♦♠♣tr ♥

❬❪ ♦rt r♠♥ ♥ r r t♦rs ♥♦♦ ♦ ♦♠tr♦♣♦♦② sr ♠str♠ ♦♥♦♥ Prs

❬❪ r rs ♥ ♦♥q Prtrt♦♥s ♥ rt① r♠♦♥ ♥② tr♥t♦♥ ♥ Pr♦♥s ♦ t t ②♠♣♦s♠ ♦♥ srt ♦rt♠s ♣s

❬❪ r rs ♥ ♦♥q Prtrt♦♥s ♥ rt① r♠♦♥ ♥② ♥ rr tr♥t♦♥s sr ♣♦rt

❬❪ r rs ♥ ♦♥q Prtrt♦♥s ♥ rt① r♠♦♥ ♥② ♥ rr tr♥t♦♥s ♦ ♣♣r ♥ sr♣♦rt

❬❪ ♦r♥s ♠♦♥ t tr♥sr s♥ ♥strtr rstt♣♦r♥tsPr♦♣s❲♦rs♦♣

❬q❪ ♥ q ♠♣②♦ ♦ ♦♥r② ♦♥t♦♥s tt♣

s♦♦r♦❲♥①♣♣♦♥r②❴♦♥t♦♥s

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❬r❪ r♥♦ r♥ ts ♠♥s ♦ r♥r ♠trs tt♣

♦r♥tsPr♦♣s❲♦rs♦♣

❬❱❪ r ♦♥ ❱rèr ♥ ♦♥q ♥t r♣rs♥tt♦♥s ♦tr♥t♦♥s ♦ rtrr② ♠♥s♦♥ Prs♦♥ ♦♠♠♥t♦♥

❬②❪ ① ②r str ♥♦♥qr ♦rt♠ ♦r ♦♥strt♥ ♥② tr♥t♦♥s ♦rt♠

❬❨❪ r♥ r♥ ♥ rtt ❨♥ ♣ s♣s ♥ ❯sr ♥ r♥ ♥ t♦r ♦r t♦♥ tt♣♦r♥tst♦❴t♠❴♠♥

♣st♠P♣♣s

❬❪ rrt sr♥♥r r♣tr ♥ ♠♥ ♥ ts♣ ♦ st ♦ ♣♦♥ts ♥ t ♣♥ r♥st♦♥s ♦♥ ♥♦r♠t♦♥♦r②

❬❪ rrt sr♥♥r ♥ r♥st P ü r♠♥s♦♥ ♣ s♣s r♥st♦♥s ♦♥ r♣s ♥r②

❬❪ rrt sr♥♥r ♥ ♠s ♥r♠♥t t♦♣♦♦ ♣♣♥♦rs ♦r rr tr♥t♦♥s ♦rt♠

❬❪ rrt sr♥♥r ♥ ♠s r♥t♥ t♦♣♦♦ s♣s♥tr♥t♦♥ ♦r♥ ♦ ♦♠♣tt♦♥ ♦♠tr② ♥ ♣♣t♦♥s

❬♦r❪ t♥ ♦rt♥ s♣♥ ♦rt♠ ♦r ❱♦r♦♥♦ r♠s ♦rt♠

❬P❪ ♥rs r ♥ ②♥ P♦♥ ♥r ③② t♦♥ s♠ ♦r ①t♦♠tr ♦♠♣tt♦♥s ♥ Pr♦♥s ♦ t ♥ rr②♥tr ♦trs♥

❬❪ ♦ ♥ ♦♥q ♥r ♣r♦r♠♠♥ ♥ t rr② ♥ ♥♥ ♦ss♦♥♥t ♥ ♦♥q t♦rs t♦♠♣tt♦♥ ♦♠tr② ♦r rs ♥ rs ♣r♥r❱r t♠ts ♥ ❱s③t♦♥

❬❱❪ t♥ ♦rt♥ ♥ rst♦♣r ❱♥ ❲② tt ♥②ss ②s ♥t ①t ♥tr rt♠t ♦r ♦♠♣tt♦♥ ♦♠tr② r♥st♦♥s ♦♥ r♣s ②

❬❲❪ ❳ ♥ ❳♥t♦ ❲♥ s♦♠trs ♥ srt s♦♠tr② sr♦♣s ♦②♣r♦ s♣s s♦ t♠t ♦r♥

❬❪ r♦ r ♥ ♦♥tr①♠♣ t♦ ♥s ♦♥tr ♦♥ ♠♥♠ srs P♦s♦♣ ③♥ ttrs

❬♣❪ ♣ r♦♣s ♦rt♠s ♣r♦r♠♠♥ s②st♠ ♦r ♦♠♣tt♦♥ srt r tt♣♣s②st♠♦r

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❬❪ ♦♥ r♠ rt♥ röts ♥ ás③ó ♦ás③ t♦rs ♥♦♦♦ ♦♠♥t♦rs sr ♠str♠ s♥♥ ❨♦r

❬❱❪ r ♠♠ r ♠ ♣ ♦♥s♦♥ ♥ ♦♥ ❱sss s♥Pttr♥s s♦♥❲s② ♥

❬❪ ♦♥s s ♦♥ ♥t ♥ rr ♥♦♠③ ♥r♠♥t ♦♥strt♦♥ ♦ ♥② ♥ ❱♦r♦♥♦ r♠s ♦rt♠

❬❪ r r♠ ♥ rt♦ árq③ ♦♠♣tt♦♥ ♦♠tr② ♦♥ rsr ♠ Psrs

❬♦❪ ♦r ❲t r② ♦♠♣tr s♥tst s♦ ♥♦ ♦t ♦t♥♣♦♥t rt♠t ♦♠♣t♥ r②s r

❬r❪ ♦♥ rts♦r♥ r ♦♠tr② ♦♠ ♦ rt t①ts ♥t♠ts ♣r♥r❱r ❨♦r

❬t❪ ♥ tr r ♦♣♦♦② ♠r ❯♥rst② Prss

❬♥❪ ♥ ♦♠♥t♦r ♥tr♦t♦♥ t♦ ♦♣♦♦② ❲ r♠♥♥ r♥s♦

❬❲❪ ❲ ♥t③s ♥ ❲♥t r♠♥s♦♥ s ♠♦r♠♥t♠ts ♥♥♥

❬❪ t♥r ♦r ♥r② ♦t♥ ♣♦♥t rt♠t t 754 −1985 ❨♦r ❨ ♣r♥t ♥ P ♦ts

❬❪ s P t♥r ♦r ♦t♥P♦♥t rt♠t ❨♦r ❨ ❯ st

❬t❪ t♥ t♦ s♥ r♦♣s ❯♥rst② ♦ ♦ Prss ♦♥ ♦♥♦♥

❬❪ ❲♠ ♦ t♦ ①② ♦r♠t♦♥ ♣r♥r Pr①s Ps♥ str ❯

❬♣❪ ♥r ♣rt tr♥t ♦♥②♦♠ tt♣♥♣

♦rr♥t❴♦tr♣

❬❪ ❲♦♥ ü♥ ♥ ♥tr ss♠♥♥ r♦♠♦r tsst♦♥ ♦ s♣ ♥ ♣rtr rt① tr♥t♦♥ ♦ t ♠♥s♦♥t♦rs ♠♥sr♣t ♠t♠t

❬P+❪ t③ tt♥r rt ♦r♥ ②♥ P♦♥ t♥ rr ♥ ❨♣ssr♦♦♠ ①♠♣s ♦ r♦st♥ss ♣r♦♠s ♥ ♦♠tr ♦♠♣tt♦♥s ♥Pr♦♥s ♦ t t r♦♣♥ ②♠♣♦s♠ ♦♥ ♦rt♠s ♦♠ ♦tr ♦ts ♥ ♦♠♣tr ♥ ♣s ♣r♥r❱r

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❬r❪ s P r②t sst♦♥s ♥ r♥r ♠trs tt♣

s♦♣♥rr♦♠tr♦♦rt♦♥sr♣r♦r♠t♠

❬❪ ♦♥ ♥tr♦t♦♥ t♦ ♦♣♦♦ ♥♦s ♣r♥r❱r ❨♦r

❬♦❪ trt P ♦② st sqr q♥t③t♦♥ ♥ P r♥st♦♥s ♦♥♥♦r♠t♦♥ ♦r②

❬❪ ♥ tr ♦ ♦rt♠s ♦r ♦♥strt♥ ♥② tr♥t♦♥s ♥tr♥t♦♥ ♦r♥ ♦ ♦♠♣tr ♥ ♥♦r♠t♦♥ ♥s

❬②♥❪ ♦r ②♥♦♥ ♥ ♥s ♦rt♠ t♠ts ♥♥♥

❬❪ s ♥ t ♦♠♦♥♦s ♣♥r P♦ss♦♥ ♣♦♥t♣r♦ss t♠t♦s♥s

❬ö❪ st ös tt♥♥ s ös ss ❩r ♦r rP♦②ër ♥ r ♠♥trr♥tst s♠♠t ❲r ♣s

❬♦❪ rt♥ ♦s♥ Pr♦t② ♥ t s♥ ♦ ♦♥ s♦s tt♣♦r♥tsPr♦♣s❲♦rs♦♣

❬❪ rs ③ó♥ ♥ ♦♠ás ♦ ❱♦r♦♥♦ r♠s ♦♥ ♦r♦s ♦♠♣tt♦♥ ♦♠tr② ♦r② ♥ ♣♣t♦♥s

❬❪ ②års ♥ Ptr ♠♥s♦♥ r♠♥s♦♥ ♣r♦❱♦r♦♥♦ r♥ ♠♦s ♥ ♠r♦♠♥ s♠t♦♥s ♦ t♦♣sst ♦♠♣tt♦♥ trs ♥

❬❪ ②♦♥ ♥♠ ♥ tr ♦♥ ❱♦r♦♥♦ r♠s ♦♥t s♣r ♦♠♣tt♦♥ ♦♠tr② ♦r② ♥ ♣♣t♦♥s

❬❪ r♥ s♥ ♥ r ♦ ②♣r♦ ❱♦r♦♥♦ r♠s ♠ s②♦♠♣t♥ sr ♣♦st♦r② ♦ s

❬♣❪ P♦♥r s ②♣r♦ ♣r ♥s tt♣♥♣♦r

P♦♥r❴s❴②♣r♦❴♣r❴♥ss

❬P❪ ②♥ P♦♥ ♥ ♦♥q tr♥t♦♥ t strtr ♥ ❯sr ♥ r♥ ♥ t♦r ♦r t♦♥ tt♣♦r♥tst♦❴t♠❴♠♥♣st♠P

❬P❪ ②♥ P♦♥ ♥ ♦♥q tr♥t♦♥s ♥ ❯sr ♥ r♥ ♥ t♦r ♦r t♦♥ tt♣♦r♥tst♦❴t♠❴♠♥

♣st♠Pr♥t♦♥

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❬♦❪ ❱♥ss ♦♥s tt ♥♠r s♥trs ♦ ♦♠♦♥♦s P♦ss♦♥ ♣♦♥t♣r♦sss P②s

❬❨❪ r♥t ♥ té♣♥ ② ♥ rtt ❨♥ ♠s ♥rt♦♥ ♥ ❯sr ♥ r♥ ♥ t♦r ♦r t♦♥ tt♣♦r♥tst♦❴t♠❴♠♥♣st♠Ps❴

❬♣❪ ♣♣rt ♥② r♥♠♥t ♦rt♠ ♦r qt② ♠♥s♦♥ ♠s♥rt♦♥ ♦r♥ ♦ ♦rt♠s

❬❱❪ ü♥tr ♦t ♥ rt ❱tr ♦♠♣tt♦♥ t♦♣♦♦② ♥ ♥tr♦t♦♥♥ ♥♥ ♦ss♦♥♥t ♥ ♦♥q t♦rs t ♦♠♣tt♦♥ ♦♠tr② ♦r rs ♥ rs ♣r♥r❱r t♠ts♥ ❱s③t♦♥

❬❨❪ r♥t ♥ ♥ rtt ❨♥ s♥ ♦♠♥s ♦♥ ②♣s s♠♦♦t srs ♥ Pr♦♥s ♦ t t ♥tr♥t♦♥ s♥♦♥t ♣s

❬❨❪ r♥t ♥ ♥ rtt ❨♥ sr ♠s ♥rt♦♥♥ ❯sr ♥ r♥ ♥ t♦r ♦r t♦♥ tt♣♦r♥tst♦❴t♠❴

♠♥♣st♠Prsr

❬♥❪ s ♥tó ♥tr ♦♠tr② ♥ ♦♠tr Pr♦t② s♦♥❲s② ♥

❬❪ ♥ ♦♥ ♥♥t ♣r♦ ♠♥♠ srs t♦t s♥trst♦♥♥ ♦t

❬❪ ♦♥t♥ ♦♥t♦♥ r♥t♥ t ①st♥ ♦ r♠♥s♦♥ ♦♥str♥ ♥② tr♥t♦♥s ♥ Pr♦♥s ♦ t t♥♥ ②♠♣♦s♠ ♦♥ ♦♠♣tt♦♥ ♦♠tr② ♣s

❬❪ ♦♥t♥ trr ♠s ♥rt♦♥ ② ♥② r♥♠♥t ♥ Pr♦♥s ♦ t t ♥♥ ②♠♣♦s♠ ♦♥ ♦♠♣tt♦♥ ♦♠tr② ♣s

❬❪ ♦♥t♥ ♣ ♦rt♠s ♦r ♦♥strt♥ r♠♥s♦♥ ♦♥str♥ ♥② tr♥t♦♥s ♥ Pr♦♥s ♦ t t♥♥ ②♠♣♦s♠ ♦♥ ♦♠♣tt♦♥ ♦♠tr② ♣s

❬♠❪ rs ♠s ♦♠♣t♥ t ♥t② Prs♥t r♦♣s ♠r❯♥rst② Prss ♠r ❯

❬♦❪ ♦♥ ♦♥♥ ♥②♦♣ ♦ ♥tr sq♥s tt♣

rsrtt♦♠⑦♥ssq♥s

❬♦❪ rr② ♦s ♣rsst♥t ♦s♠ ♥ ts ♠♥t strtr ♦r② ♥ ♠♣♠♥tt♦♥ r❳

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❬♣❪ ♥ ♣♥r r ♦♣♦♦② r ♦♦ ♦♠♣♥② ❨♦r

❬♣r❪ ❱♦r ♣r♥ ♦♠♣tt♦♥ ②♥♠s ♥ ❱♦r♦♥♦ tsst♦♥s tt♣s♦♣♥rr♦♠tr♦♦rt♦♥sr

♣r♦r♠t♠

❬♣r❪ ❱♦r ♣r♥ ♣r s ♠♦ ♥♥r♥t ♦s♠♦♦ ②r♦②♥♠ s♠t♦♥s ♦♥ ♠♦♥ ♠s ♦♥t② ♦ts ♦ t ♦②str♦♥♦♠ ♦t②

❬t❪ ♦♥ t ♦♠tr② ♦ rs ♣r♥r❱r ❨♦r

❬❪ ♦♥ ♥ s tt♣t♦rs♠t♠ss♦tr

❬♦❪ ❲♠ ♦♠s♦♥ ♥ t s♦♥ ♦ s♣ t ♠♥♠♠ ♣rtt♦♥ rP♦s♦♣ ③♥

❬♦❪ rst♥ ♦♠♣s♦♥ st ♥ r♦st ♥② tsst♦♥ ♥ ♣r♦♦♠♥s ♥tr♥t♦♥ ♦r♥ ♦r ♠r t♦s ♥ ♥♥r♥

❬r❪ ❲♠ r r♣♣♥r ♥♥♥ r äss♥ ♠r ❲ss♥st♥ t♠tsP②ss ss

❬❪ ❲♠ rst♦♥ r♠♥s♦♥ ♦♠tr② ♥ ♦♣♦♦② ❱♦♠ Pr♥t♦♥ ❯♥rst② Prss rs②

❬❪ ❲♠ P rst♦♥ ♦♠tr② ♥ ♦♣♦♦② ♦ r♥♦s tt♣♠sr♦r♣t♦♥s♦♦st♠

❬♦❪ ♥ ♦r♥♦s ♣t♠st♦♥ ♠s ès ♦t♦rt ♥ s♥s❯♥rsté ♦♣♥t♣♦s r♥

❬❱❪ ést♥ ❱tt Prs♦♥ ♦♠♠♥t♦♥ tt♣rts

♥s②♦♥r⑦tt

❬❲❪ ♥ ♥ ❲rt ♥ ❲♠ ♣ ♦s♠ ♦♠tr ♥②ss tt♣str♦r♥⑦②rtt♠♣t♦♥

②♣

❬❲❱P+❪ ♥ ♥ ❲rt rt ❱tr r♥ Pt♥ ♦ r♥ ♥ ♦rt♦ ♣ s♣ t♦♣♦♦② ♦ t ♦s♠ r❳❱

❬❱❨❪ rt ❱tr ♥ ❨♣ ♦♠♣tt♦♥ ♦♠♣①t② ♦ ♦♠♥t♦rsrs ♥ Pr♦♥s ♦ t t ♥♥ ②♠♣♦s♠ ♦♥ ♦♠♣tt♦♥♦♠tr② ♣s

❬❲t❪ ❲ts♦♥ ♦♠♣t♥ t n♠♥s♦♥ ♥② tsst♦♥ t♣♣t♦♥s t♦ ❱♦r♦♥♦ ♣♦②t♦♣s ♦♠♣tr ♦r♥

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❬❲❪ ❲ss ♦ ②r♦♣♦ ♠♥strr♥ ts srr♦♥♥ tr strtr ♦♠tr ♠♥r tt♣s♦♣♥rr♦♠tr r

❬❲❪ P ❲s♦♥ r ♣s ♠r ❯♥rst② Prss ♠r

❬❨❪ rtt ❨♥ tr♥t♦♥s ♥ ❯sr ♥ r♥ ♥ t♦r ♦r t♦♥ tt♣♦r♥

tst♦❴t♠❴♠♥♣st♠Pr♥t♦♥

❬❩♦♠❪ r ❩♦♠♦r♦♥ ♦♣♦♦② ♦r ♦♠♣t♥ ♠r ❯♥rst② Prss♠r

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Page 125: Triangulating Point Sets in Orbit Spaces · 2020-05-21 · iii Abstract In this work we discuss triangulations of di erent topological spaces for given point sets. We propose both