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Large Scale Topic Detection using Node-Cut Partitioning on Dense Weighted-Graphs

Kambiz GhoorchianŠarūnas Girdzijauskas

ghoorian@kth.se22.06.2016

• Motivation

• Solution

• Results

• Conclusion

2

What is a Topic (Trending Topic)?

3

#ChewbaccaMom

What is a Topic (Trending Topic)?

4

#ChewbaccaMom #Aylan

#uselections2016

#susanboyle

#Apple

#Wimbledon

#FacebookIsDown

#Superbowl

#Politics

#JobMarket

#Stefanlöfven#Sport #Euro2016

#TweetDeck

#FindingDory

رمضان#

#IranElection

#Immigration

#Russia

#Trump

5

Why Topics (Trends) are Important?

6

Why Topics (Trends) are Important?

7

Why Topics (Trends) are Important?

Given a large number of documents (e.g., tweets), how can we extract the

most frequent (significant) topics (trends)?

8

What is Topic Detection?

Current Solutions

9

Current Solutions

10

• Statistical Topic Modeling

• Machine Learning

Current Solutions

11

• Statistical Topic Modeling

• Matrix Factorization

• Latent Dirichlet Allocation (LDA)[1]

• Hierarchical LDA (HLDA)

• Machine Learning

W1 W2 W3 W4 …D1 1 0 1 1 …D2 0 1 0 1 …D3 0 0 1 1 …

…Dn 1 1 0 1 …

Document-Term

T1 T2 T1 … TkW1 0.1 0.6 0.01 … 0.2W2 0.7 0.1 0.1 … 0.02W3 0.01 0.1 0.4 … 0.4

…Wm 0.2 0.4 0.4 … 0.0

Word-Topic

T1 T2 T1 … TkD1 0.1 0.6 0.01 … 0.2D2 0.7 0.1 0.1 … 0.02D3 0.01 0.1 0.4 … 0.4

…Dn 0.2 0.4 0.4 … 0.0

Document-Topic

1. David M. Blei, Andrew Y. Ng, Michael I. Jordan; “Latent Dirichlet Allocation” 3(Jan):993-1022, 2003.

Current Solutions

12

• Statistical Topic Modeling

• Matrix Factorization

• Latent Dirichlet Allocation (LDA)[1]

• Hierarchical LDA (HLDA)

• Machine Learning

1. Document Modeling

• Vector Modeling

• Graph Modeling

2. Topic Detection

• Unsupervised - Clustering

• Supervised - Classification

W1 W2 W3 W4 …D1 1 0 1 1 …D2 0 1 0 1 …D3 0 0 1 1 …

…Dn 1 1 0 1 …

Document-Term

T1 T2 T1 … TkW1 0.1 0.6 0.01 … 0.2W2 0.7 0.1 0.1 … 0.02W3 0.01 0.1 0.4 … 0.4

…Wm 0.2 0.4 0.4 … 0.0

Word-Topic

T1 T2 T1 … TkD1 0.1 0.6 0.01 … 0.2D2 0.7 0.1 0.1 … 0.02D3 0.01 0.1 0.4 … 0.4

…Dn 0.2 0.4 0.4 … 0.0

Document-Topic

1. David M. Blei, Andrew Y. Ng, Michael I. Jordan; “Latent Dirichlet Allocation” 3(Jan):993-1022, 2003.

Limitations

13

Limitations• Sparsity

• Short messages have Less informative co-occurrence patterns which results in[1]:

1. False segmentation of topics.

2. Difficulty in identification of ambiguous words (Apple, Computer vs Fruit).

14

[1] - Liangjie et al, “Empirical Study of Topic Modeling in Twitter. SOMA 2010”

[2] - http://www.statista.com/statistics/282087/number-of-monthly-active-twitter-users/

Limitations• Sparsity

• Short messages have Less informative co-occurrence patterns which results in[1]:

1. False segmentation of topics.

2. Difficulty in identification of ambiguous words (Apple, Computer vs Fruit).

• Dynamism

• Constant emergent of New phrases or Acronyms

• (e.g., Selfie, Unlike, Phablet, IAVS = I am very sorry, IWSN = I want sex now).

15

[1] - Liangjie et al, “Empirical Study of Topic Modeling in Twitter. SOMA 2010”

[2] - http://www.statista.com/statistics/282087/number-of-monthly-active-twitter-users/

Limitations• Sparsity

• Short messages have Less informative co-occurrence patterns which results in[1]:

1. False segmentation of topics.

2. Difficulty in identification of ambiguous words (Apple, Computer vs Fruit).

• Dynamism

• Constant emergent of New phrases or Acronyms

• (e.g., Selfie, Unlike, Phablet, IAVS = I am very sorry, IWSN = I want sex now).

• Scalability

• 310M active-users/month [2]

• 500M messages/day [2]

16

[1] - Liangjie et al, “Empirical Study of Topic Modeling in Twitter. SOMA 2010”

[2] - http://www.statista.com/statistics/282087/number-of-monthly-active-twitter-users/

Solution

17

Unsupervised learning: 1-Graph Modeling 2-Node-cut Partitioning

DocumentsD1D2D3D4D5D6…

18

SolutionUnsupervised learning: 1-Graph Modeling 2-Node-cut Partitioning

DocumentsD1D2D3D4D5D6…

19

1 - Graph Modeling

SolutionUnsupervised learning: 1-Graph Modeling 2-Node-cut Partitioning

Random Indexing Knowledge Base

Word RI VectorW1 V1W2 V2W3 V3W4 V4W5 V5W6 V6W7 V7W8 V8…. …

DocumentsD1D2D3D4D5D6…

20

1 - Graph Modeling

SolutionUnsupervised learning: 1-Graph Modeling 2-Node-cut Partitioning

Random Indexing Knowledge Base

Word RI VectorW1 V1W2 V2W3 V3W4 V4W5 V5W6 V6W7 V7W8 V8…. …

DocumentsD1D2D3D4D5D6…

2 - Node-Cut Partitioning

21

1 - Graph Modeling

SolutionUnsupervised learning: 1-Graph Modeling 2-Node-cut Partitioning

1 - Graph Modeling using Random Indexing

22

Random Indexing (RI)• Is a dimensionality reduction method (similar to hashing).

23 23

Random Indexing (RI)• Is a dimensionality reduction method (similar to hashing).

24 24

DocumentsD1 = {W1, W4, W8, …}

D2D3D4D5D6…

Random Indexing (RI)• Is a dimensionality reduction method (similar to hashing).

25 25

Random Indexing Knowledge Base

Word

RI VectorW1 V1 = {a1, b1, c1, d1, e1, f1}W2W3W4 V4 = {a4, b4, c4, d4, e4, f4}W5W6W7W8 V8 = {a8, b8, c8, d8, e8, f8}…. …

DocumentsD1 = {W1, W4, W8, …}

D2D3D4D5D6…

Random Indexing

Random Indexing (RI)• Is a dimensionality reduction method (similar to hashing).

26 26

Random Indexing Knowledge Base

Word

RI VectorW1 V1 = {a1, b1, c1, d1, e1, f1}W2W3W4 V4 = {a4, b4, c4, d4, e4, f4}W5W6W7W8 V8 = {a8, b8, c8, d8, e8, f8}…. …

DocumentsD1 = {W1, W4, W8, …}

D2D3D4D5D6…

Random Indexing

1. Unique

2. Fixed length

3. Captures Co-occurrence patterns of the words

Random Indexing (RI)• Is a dimensionality reduction method (similar to hashing).

27 27

Random Indexing Knowledge Base

Word

RI VectorW1 V1 = {a1, b1, c1, d1, e1, f1}W2W3W4 V4 = {a4, b4, c4, d4, e4, f4}W5W6W7W8 V8 = {a8, b8, c8, d8, e8, f8}…. …

DocumentsD1 = {W1, W4, W8, …}

D2D3D4D5D6…

Random Indexing

1. Unique

2. Fixed length

3. Captures Co-occurrence patterns of the words

Graph Modeling

28

Graph Modeling

29

Documents

D1 = {W1, W4, W8, …}

D2 = {W2, W3, W7, …}

D3 = {W4, W1, W3, …}

D4 = {W2, W6, W9, …}

D5 = {W3, W4, W8, …}

D6 = {W1, W3, W7, …}

RI - Knowledge Base

Word

RI VectorW1 V1 = {a1, b1, c1, d1, e1, f1}W2 V2 = {a2, b2, c2, d2, e2, f2}W3 V3 = {a3, b3, c3, d3, e3, f3}W4 V4 = {a4, b4, c4, d4, e4, f4}W5 V5 = {a5, b5, c5, d5, e5, f5}W6 V6 = {a6, b6, c6, d6, e6, f6}W7 V7 = {a7, b7, c7, d7, e7, f7}W8 V8 = {a8, b8, c8, d8, e8, f8}…. …

Graph Modeling

30

Documents

D1 = {W1, W4, W8, …}

D2 = {W2, W3, W7, …}

D3 = {W4, W1, W3, …}

D4 = {W2, W6, W9, …}

D5 = {W3, W4, W8, …}

D6 = {W1, W3, W7, …}

RI - Knowledge Base

Word

RI VectorW1 V1 = {a1, b1, c1, d1, e1, f1}W2 V2 = {a2, b2, c2, d2, e2, f2}W3 V3 = {a3, b3, c3, d3, e3, f3}W4 V4 = {a4, b4, c4, d4, e4, f4}W5 V5 = {a5, b5, c5, d5, e5, f5}W6 V6 = {a6, b6, c6, d6, e6, f6}W7 V7 = {a7, b7, c7, d7, e7, f7}W8 V8 = {a8, b8, c8, d8, e8, f8}…. …

Graph Modeling

31

Documents

D1 = {W1, W4, W8, …}

D2 = {W2, W3, W7, …}

D3 = {W4, W1, W3, …}

D4 = {W2, W6, W9, …}

D5 = {W3, W4, W8, …}

D6 = {W1, W3, W7, …}

RI - Knowledge Base

Word

RI VectorW1 V1 = {a1, b1, c1, d1, e1, f1}W2 V2 = {a2, b2, c2, d2, e2, f2}W3 V3 = {a3, b3, c3, d3, e3, f3}W4 V4 = {a4, b4, c4, d4, e4, f4}W5 V5 = {a5, b5, c5, d5, e5, f5}W6 V6 = {a6, b6, c6, d6, e6, f6}W7 V7 = {a7, b7, c7, d7, e7, f7}W8 V8 = {a8, b8, c8, d8, e8, f8}…. …

a b

c

e

b

f c

d

a b

f

e d

Graph Modeling

32

Documents

D1 = {W1, W4, W8, …}

D2 = {W2, W3, W7, …}

D3 = {W4, W1, W3, …}

D4 = {W2, W6, W9, …}

D5 = {W3, W4, W8, …}

D6 = {W1, W3, W7, …}

RI - Knowledge Base

Word

RI VectorW1 V1 = {a1, b1, c1, d1, e1, f1}W2 V2 = {a2, b2, c2, d2, e2, f2}W3 V3 = {a3, b3, c3, d3, e3, f3}W4 V4 = {a4, b4, c4, d4, e4, f4}W5 V5 = {a5, b5, c5, d5, e5, f5}W6 V6 = {a6, b6, c6, d6, e6, f6}W7 V7 = {a7, b7, c7, d7, e7, f7}W8 V8 = {a8, b8, c8, d8, e8, f8}…. …

a b

c

e

b

f c

d

a b

f

e d

a b

f c

e d

Graph Modeling

a

f

e d

33

e

b

f c

d

a b

f c

e d

a

e

c

d

Documents

D1 = {W1, W4, W8, …}

D2 = {W2, W3, W7, …}

D3 = {W4, W1, W3, …}

D4 = {W2, W6, W9, …}

D5 = {W3, W4, W8, …}

D6 = {W1, W3, W7, …}

RI - Knowledge Base

Word

RI VectorW1 V1 = {a1, b1, c1, d1, e1, f1}W2 V2 = {a2, b2, c2, d2, e2, f2}W3 V3 = {a3, b3, c3, d3, e3, f3}W4 V4 = {a4, b4, c4, d4, e4, f4}W5 V5 = {a5, b5, c5, d5, e5, f5}W6 V6 = {a6, b6, c6, d6, e6, f6}W7 V7 = {a7, b7, c7, d7, e7, f7}W8 V8 = {a8, b8, c8, d8, e8, f8}…. …

Graph Modeling

34

Documents

D1 = {W1, W4, W8, …}

D2 = {W2, W3, W7, …}

D3 = {W4, W1, W3, …}

D4 = {W2, W6, W9, …}

D5 = {W3, W4, W8, …}

D6 = {W1, W3, W7, …}

RI - Knowledge Base

Word

RI VectorW1 V1 = {a1, b1, c1, d1, e1, f1}W2 V2 = {a2, b2, c2, d2, e2, f2}W3 V3 = {a3, b3, c3, d3, e3, f3}W4 V4 = {a4, b4, c4, d4, e4, f4}W5 V5 = {a5, b5, c5, d5, e5, f5}W6 V6 = {a6, b6, c6, d6, e6, f6}W7 V7 = {a7, b7, c7, d7, e7, f7}W8 V8 = {a8, b8, c8, d8, e8, f8}…. …

Graph Modeling

35

Documents

D1 = {W1, W4, W8, …}

D2 = {W2, W3, W7, …}

D3 = {W4, W1, W3, …}

D4 = {W2, W6, W9, …}

D5 = {W3, W4, W8, …}

D6 = {W1, W3, W7, …}

RI - Knowledge Base

Word

RI VectorW1 V1 = {a1, b1, c1, d1, e1, f1}W2 V2 = {a2, b2, c2, d2, e2, f2}W3 V3 = {a3, b3, c3, d3, e3, f3}W4 V4 = {a4, b4, c4, d4, e4, f4}W5 V5 = {a5, b5, c5, d5, e5, f5}W6 V6 = {a6, b6, c6, d6, e6, f6}W7 V7 = {a7, b7, c7, d7, e7, f7}W8 V8 = {a8, b8, c8, d8, e8, f8}…. …

2 - Node-Cut Partitioning

2 - Node-Cut Partitioning

36

Node-Cut PartitioningJa-Be-Ja-VC[1]

balanced,

k-way partitioning

for un-weighted graphs

based on node-cut minimization.

37

1. F Rahimian, AH Payberah, S Girdzijauskas, S Haridi: Distributed Vertex-cut Partitioning, in Distributed Applications and Interoperable Systems, 186-200, 2014.

Node-Cut Partitioning

38

39

Random Initialization

k = 2

Node-Cut Partitioning

40

Random Initialization Iteration

e e’

k = 2

HeatGain

C = BlueC’ = Red

Node-Cut Partitioning

41

Random Initialization Iteration

e e’e e’

k = 2

HeatGain

C = BlueC’ = Red

Node-Cut Partitioning

42

Random Initialization Iteration Iteration

e e’e e’e

e’e

e’

k = 2

HeatGain

C = BlueC’ = Red

Node-Cut Partitioning

43

Random Initialization Iteration Iteration

e e’e e’e

e’e

e’

k = 2

HeatGain

C = BlueC’ = Red Minimum Cut Size

Node-Cut Partitioning

• Same Utility Function

• Weighted Gain factor

• Weighted Cut

Modifications

44 44

HeatGain

Modifications

45 45

5 , 5

e e’e

5 , 5Un-Weighted Graph

11 , 11

e1

133 1 1

1

5

1

3

3

13 , 9

e e’1

133 1 1

1

5

1

3

3

Weighted Graph

Modifications

46 46

5 , 5

e e’e

5 , 5Un-Weighted Graph

11 , 11

e1

133 1 1

1

5

1

3

3

11 , 11

ee’

1

13

3 1 11

5

1

3

3

Weighted Graph

11 , 11

e1

133 1 1

1

5

1

3

3

13 , 9

e e’1

133 1 1

1

5

1

3

3

Weighted Graph

Modifications

47 47

5 , 5

e e’e

5 , 5Un-Weighted Graph

11 , 11

e1

133 1 1

1

5

1

3

3

13 , 9

e e’1

133 1 1

1

5

1

3

3

Weighted Graph

1. Scalability

2. Convergence

11 , 11

e1

133 1 1

1

5

1

3

3

11 , 11

ee’

1

13

3 1 11

5

1

3

3

Weighted Graph

Modifications

48 48

11 , 11

13 , 9e

1

1

3

3

1

11

5

1

3

3

e e’

1

1

3

3

1

11

5

1

3

3

Modifications

49 49

11 , 11

13 , 9e

1

1

3

3

1

11

5

1

3

3

e e’

1

1

3

3

1

11

5

1

3

3

12 , 10

ee’1

1

1

3

3

1

11

5

1

3

3

e’2

Experiments

50

Experiments1. Accuracy (Quantitative)

• SNAP Twitter Trending Topics from 2009 [1]

• EXP1 - 3 Topics

• 2531 Documents

• K = 100

• Sam = 20%

• EXP2 - 8 Topics

• 23175 Documents

• K = 100

• Sam = 20%

A. Scalability (Qualitative)

• TREC Tweets 2011 - 16M Tweets [2]

• EXP3

• 275336 Documents

51

SNAP Twitter 2009

Topic Acronym EXP1 EXP2

Harry Potter (HP) HP 1457 —

American Idol (AI) AI — 4241

Dollhouse (DH) DH — 1262

Slumdog Milliner (SM) SM — 280

Susan Boyle (SB) SB 555 992

Swine Flue (SF) SF 519 1944

Tiger Wood (TW) TW — 2242

Tweetdeck (TD) TD — 5860

Wimbledon (WI) WI — 6354

1. https://snap.stanford.edu/data/ 2. http://trec.nist.gov/data/tweets/

Experiments

52

• Comparison

• GibsLDA - baseline [1]

• BiTerm - Best known solution[2]

1. David M. Blei, Andrew Y. Ng, Michael I. Jordan; “Latent Dirichlet Allocation” 3(Jan):993-1022, 2003. 2. Yan, Xiaohui and Guo, Jiafeng and Lan, Yanyan and Cheng, Xueqi, “A Biterm Topic Model for Short Texts”, WWW ’13.

Experiments - Evaluation• F1-Score (Quantitative)

• Average Coherence Score (Qualitative)

53

= [0 1]

= [Log(k/n) Log(1+k/n)]= [- ∞ 0.000001]

54

EXP1 - SNAP 3 Topics - F-ScoreBi

Term

LDA

Our

’s

55

EXP2 - SNAP 8 Topics - F-ScoreLD

ABi

Term

Our

’s

• Tweets 300K

• Edges 7,9M

• Vertices 4000

• Avg_Deg 3948

• Partitions 500

• Duration

• LDA 1684s

• BiTerm 1973s

• Our Algorithm 7000s (Centralized)

56

EXP3 - Twitter Large Large Dataset - Average Coherence Score - K=500

Num Top Words 20 10 5

LDA -637.75 -162.96 -41.52

BiTerm -597.5 -143.45 -34.3

Our Algorithm -582.0 -166.15 -49.59

EXP3 - TREC - Coherency

57

EXP1 - Twitter 3 Topics - Average Coherency Score - K=100

Num Top Words 20 10 5

LDA -37.94 -15.85 -5.3

BiTerm -32.05 -12.57 -4.32

Our Algorithm -20.62 -9.12 -3.25

EXP1 - SNAP 3 Topics - Coherency

• Tweets 2K

• Edges 2.3M

• Vertices 3994

• Avg_Deg 1175

• Partitions 100

• Duration

• LDA 1.3s

• BiTerm 2s

• Our Algorithm 6000s (Centralized)

58

EXP1 - Twitter 8 Topics - Average Coherence Score - K=100

Num Top Words 20 10 5

LDA -162.89 -52.52 -13.88

BiTerm -141.37 -42.16 -11.15

Our Algorithm -124.67 -37.24 -9.18

EXP2 - SNAP 8 Topics - Coherency

• Tweets 2K

• Edges 7,5M

• Vertices 4000

• Avg_Deg 3779

• Partitions 100

• Duration

• LDA 7S

• BiTerm 24S

• Our Algorithm 6000s (Centralized)

59

Scalability

Duration Growth RatePe

rcen

tage

• Achievements

• Efficient and scalable solution for topic detection.

• Solves Sparsity and Dynamism using RI Knowledge-base

• Meets Scalability using Graph Partitioning

• Future work

• Enhance initialization and language modeling

• Extend the algorithm to an streaming model since Graph construction is incremental

60

Conclusion

Thank You

Questions?

Bibliography1. Sahlgren, M. (2005) An Introduction to Random Indexing, Proceedings of the Methods and Applications of Semantic Indexing Workshop at the 7th

International Conference on Terminology and Knowledge Engineering, TKE 2005, August 16, Copenhagen, Denmark. 2. Kanevara, P: Sparse Distributed Memory and Related Models. Associative Neural Memories, Oxford University Press, 1993. 3. Kanerava, P., Kristoferson, J., and Holst, A. (2000). Random indexing of text samples for latent semantic analysis. In Gleitman, L. R. and Josh, A. K.,

editors, Proceedings of the 22nd Annual Conference of the Cognitive Science Society, page 1036, Mahwah, New Jersey. Erlbaum. 4. Johnson, W. and Lindenstrauss, J. (1984). Extensions of Lipschitz mappings into a Hil- bert space. In Beals, R., Beck, A., Bellow, A., and Hajian, A.,

editors, Conference on Modern Analysis and Probability (1982: Yale University), volume 26 of Con- temporary Mathematics, pages 189–206. American Mathematical Society.

5. K Ghoorchian, F Rahimian, S Girdzijauskas: Semi Supervised Multiple Disambiguation, Trustcom/BigDataSE/ISPA, 2015 IEEE 2, 88-95.

img1. Img 1 - http://www.studerasmart.nu/wp-content/uploads/2012/04/jobb-och-cv.png 2. Img 2 - http://gfx2.aftonbladet-cdn.se/image/19456728/485/normal/efc46e3660c6c/hedenmo3.jpg 3. Img 3 - http://cdn01.nyheter24.se/c4ab6c0402fa00a700/2014/04/03/941973/Sk%C3%A4rmavbild%202014-04-03%20kl.%2020.54.47.png 4. Img 4 - http://ericagelfandlaw.com/wp-content/uploads/2015/12/immigration.jpg

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