LING 388: Language and Computers

Sandiway FongLecture 13

Administrivia

• Another Homework on recursion– Homework 5 – due next Wednesday by midnight…

Left to Right Recursive Transformation

1. np --> np, pp.2. np --> det, nn.

x --> [z], v.v --> [y], v.v --> [y].x --> [z].

x(x(z,V)) --> [z], v(V).v(v(y,V)) --> [y], v(V).v(v(y)) --> [y].x(x(z)) --> [z].

np --> det, nn, v.v --> pp, v.v --> pp.np --> det, nn. np(np(D,N,V)) --> det(D), nn(N), v(V).

v(v(PP,V)) --> pp(PP), v(V).v(v(PP)) --> pp(PP).np(np(D,NN)) --> det(D), nn(NN).

Last TimeWe developed the following rules:1. sentence(s(X,Y)) --> np(X), vp(Y).2. pp(pp(X,Y)) --> in(X), np(Y).3. np(np(X)) --> prp(X).4. np(np(nnp(mary))) --> [mary].5. np(np(nnp(john))) --> [john].6. np(np(nnp(bill))) --> [bill].7. np(np(D,NN)) --> det(D), nn(NN).8. np(np(D,NN,V)) --> det(D), nn(NN), v(V).9. v(v(PP,V)) --> pp(PP), v(V).10. v(v(PP)) --> pp(PP).11. v2(v2(PP,V2)) --> pp(PP), v2(V2).12. v2(v2(PP)) --> pp(PP).13. vp(vp(V,NP,V2)) --> verb(V), np(NP), v2(V2).14. vp(vp(V,X)) --> verb(V), np(X).15. vp(vp(V,X)) --> verb(V), sbar(X).16. sbar(sbar(X,S)) --> c(X), sentence(S).

17. c(in(that)) --> [that].18. in(in(with)) --> [with].19. a(jj(big)) --> [big].20. a(jj(shiny)) --> [shiny].21. a(jj(red)) --> [red].22. prp(prp(i)) --> [i].23. prp(prp(me)) --> [me].24. nn(nn(boy)) --> [boy].25. nn(nn(limp)) --> [limp].26. nn(nn(telescope)) --> [telescope].27. nn(nn(bus)) --> [bus].28. nn(nn(A,NN)) --> a(A), nn(NN).29. verb(vbd(noticed)) --> [noticed].30. verb(vbd(saw)) --> [saw].31. det(dt(the)) --> [the].32. det(dt(a)) --> [a].

Left recursive np np, pp and vp vp, pp adjunction rules transformed into right recursive rules involving v and v2, respectivelygrammar-transformed.pl

Last Time1. sentence(s(X,Y)) --> np(X), vp(Y).2. pp(pp(X,Y)) --> in(X), np(Y).3. np(np(X)) --> prp(X).4. np(np(nnp(mary))) --> [mary].5. np(np(nnp(john))) --> [john].6. np(np(nnp(bill))) --> [bill].7. np(np(D,NN)) --> det(D), nn(NN).8. np(np(np(X,Y),Z)) --> det(X), nn(Y),

pp(Z).9. vp(vp(V,X)) --> verb(V), np(X).10. vp(vp(V,NP,PP)) --> verb(V), np(NP),

pp(PP).11. vp(vp(V,X)) --> verb(V), sbar(X).12. sbar(sbar(X,S)) --> c(X), sentence(S).

13. c(in(that)) --> [that].14. in(in(with)) --> [with].15. a(jj(big)) --> [big].16. a(jj(shiny)) --> [shiny].17. a(jj(red)) --> [red].18. prp(prp(i)) --> [i].19. prp(prp(me)) --> [me].20. nn(nn(boy)) --> [boy].21. nn(nn(limp)) --> [limp].22. nn(nn(telescope)) --> [telescope].23. nn(nn(bus)) --> [bus].24. nn(nn(A,NN)) --> a(A), nn(NN).25. verb(vbd(noticed)) --> [noticed].26. verb(vbd(saw)) --> [saw].27. det(dt(the)) --> [the].28. det(dt(a)) --> [a].

Quick Fix grammargrammar-quickfix.pl

Step 4

• Step 4:– Compare the transformed grammar parses with

those obtained using the “Quick Fix” grammar on the NP• a boy with a telescope with a limp• number of parses?• attachment of the PPs?

Last TimeModification Relations Quick Fix PP adjunction to NP/PP

telescope boy, limp boy ✅

telescope see, limp see ✅

telescope boy, limp see ✅ ✅

telescope see, limp telescope ✅ ✅

telescope boy, limp telescope ✅ ✅

Example: I saw the boy with a telescope with a limp

Left to Right Recursive Transformation

Structures are right branchingThey have extra v and v2 nodes

Step 5

• Step 5:– in step 4, we obtained a

right recursive parse– Modify your natural

language grammar to produce a left recursive parse following the template on the right…

– Test your grammar

• Example:– x(x(z,V)) --> [z], v(V).– v(v(y,V)) --> [y], v(V).– v(v(v)) --> [y].– x(x(z)) --> [z].

• Modified grammar:

Homework 5

• Regular sentence:– the rat ate the cheese

• Object relative clause construction:– object of the sentence is missing– "moves" to become a new head noun– the cheese (that) the rat ate– [NP [NP the cheese] [SBAR [S [NP the rat][VP[VBD

ate] ____ ]]]]

Homework 5

• Subject relative clause construction:– subject "moves" to become a new head noun– the rat that ate the cheese– [NP [NP the rat] [SBAR that [S ____ [VP[VBD ate] [NP the

cheese]]]]]

Homework 5

• Implement another kind of recursion:– Object relative clauses• the cat that saw the rat that saw the cheese that …• [NP the cat [SBAR that [S saw [NP the rat [SBAR that [S saw [NP

the cheese that … ]]]]]]]• the cheese that the rat ate• the cheese that the rat that the cat saw ate• the cheese that the rat that the cat that the dog chased

saw ate

Homework 5

• Other kinds of recursion, e.g.– Object relative clauses

• the cheese that the rat ate

Homework 5

• Other kinds of recursion, e.g.– Object relative clauses

• the cheese that the rat that the cat saw ate

Homework 5

• the cheese that the rat that the cat saw ate was rotten .

Homework 5• the cheese that the rat that the cat that the dog chased saw ate was rotten .

Homework 5

• Use grammar.pl as the starting point• Submit your revised grammar.• Submit your runs