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Encoding Linguistic Structures with Graph Convolutional Networks Diego Marcheggiani Joint work with Ivan Titov and Joost Bastings University of Amsterdam University of Edinburgh @South England NLP Meetup

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Page 1: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Encoding Linguistic Structures with Graph Convolutional Networks

Diego MarcheggianiJoint work with Ivan Titov and Joost Bastings

University of AmsterdamUniversity of Edinburgh

@South England NLP Meetup

Page 2: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Structured (Linguistic) Priors

Sequa makes and repairs jet engines.

creator

creation

entity repaired

repairer

SBJ COORD

OBJ

CONJ NMOD

ROOT

“I voted for Palpatine because he was

most aligned with my values,” she said.

2

Page 3: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Sequence to Sequence

3

[Sutskever et al., 2014]

the black cat

le chat noire <\s>

<s> le chat noire

Page 4: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Sequence to Sequence

} Language is not (only) a sequence of words} We have linguistic knowledge

4

[Sutskever et al., 2014]

the black cat

le chat noire <\s>

<s> le chat noire

Page 5: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Sequence to Sequence

} Language is not (only) a sequence of words} We have linguistic knowledge

Encode structured linguistic knowledge into NN using Graph Convolutional Networks

5

the black cat

le chat noire <\s>

<s> le chat noire

Page 6: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Outline

} Semantic Role Labeling} Graph Convolutional Networks (GCN)} Syntactic GCN for Semantic Role Labeling (SRL)} SRL Model} Exploiting Semantics in Neural Machine Translation with GCNs

Encoding Sentences with Graph Convolutional Networks for Semantic Role LabelingDiego Marcheggiani, Ivan Titov. In Proceedings of EMNLP, 2017.

Exploiting Semantics in Neural Machine Translation with Graph Convolutional NetworksDiego Marcheggiani, Joost Bastings, Ivan Titov. In Proceedings of NAACL-HLT, 2018.

6

Page 7: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Semantic Role Labeling

} Predicting the predicate-argument structure of a sentence

Sequa makes and repairs jet engines.Sequa makes and repairs jet engines.

7

Page 8: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Semantic Role Labeling

} Predicting the predicate-argument structure of a sentence} Discover and disambiguate predicates

8

Sequa makes and repairs jet engines.make.01 repair.01

Sequa makes and repairs jet engines.

Page 9: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

} Predicting the predicate-argument structure of a sentence} Discover and disambiguate predicates} Identify arguments and label them with their semantic roles

Sequa makes and repairs jet engines.make.01 repair.01

Creator

Semantic Role Labeling

9

Page 10: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

} Predicting the predicate-argument structure of a sentence} Discover and disambiguate predicates} Identify arguments and label them with their semantic roles

Sequa makes and repairs jet engines.make.01 repair.01

Creator

Creation

Semantic Role Labeling

10

Page 11: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

} Predicting the predicate-argument structure of a sentence} Discover and disambiguate predicates} Identify arguments and label them with their semantic roles

Sequa makes and repairs jet engines.make.01 repair.01

Creator

Creation

Entity repaired

Repairer

Semantic Role Labeling

11

Page 12: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Semantic Role Labeling

} Only the head of an argument is labeled} Sequence labeling task for each predicate} Focus on argument identification and labeling

12

Sequa makes and repairs jet engines.make.01 repair.01

Creator

Creation

Entity repaired

Repairer

Page 13: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Semantic Role Labeling

13

Question answeringNarayanan and Harabagiu 2004

Shen and Lapata 2007 Khashabi et al. 2018

Machine translationWu and Fung 2009

Aziz et al. 2011

Information extractionSurdeanu et al. 2003

Christensen et al. 2010

Page 14: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Related work

14

Tutorial on Semantic Role Labeling at EMNLP 2017

Page 15: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Related work

} SRL systems that use syntax with simple NN architectures} [FitzGerald et al., 2015]} [Roth and Lapata, 2016]

} Recent models ignore linguistic bias } [Zhou and Xu, 2014]} [He et al., 2017]} [Marcheggiani et al., 2017]

15

Tutorial on Semantic Role Labeling at EMNLP 2017

Page 16: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Motivations

} Some semantic dependencies are mirrored in the syntactic graph

Sequa makes and repairs jet engines.

creator

creation

SBJ COORD

OBJ

CONJ NMOD

ROOT

16

Page 17: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Sequa makes and repairs jet engines.

creator

creation

entity repaired

repairer

SBJ COORD

OBJ

CONJ NMOD

ROOT

Motivations

} Some semantic dependencies are mirrored in the syntactic graph} Not all of them – syntax-semantics interface is not trivial

17

Page 18: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Outline

} Semantic Role Labeling} Graph Convolutional Networks (GCN)} Syntactic GCN for Semantic Role Labeling (SRL)} SRL Model} Exploiting Semantics in Neural Machine Translation with GCNs

18

Page 19: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Graph Convolutional Networks (message passing)

Undirected graph

[Gori et al. 2005 Scarselli et al. 2009Kipf and Welling, 2016]

19

Page 20: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Graph Convolutional Networks (message passing)

Undirected graph Update of the blue node

[Gori et al. 2005 Scarselli et al. 2009Kipf and Welling, 2016]

20

Page 21: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Graph Convolutional Networks (message passing)

Undirected graph Update of the blue node

[Kipf and Welling, 2016]

21

hi = ReLU

0

@W0hi +X

j2N (v)

W1hj

1

A

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NeighborhoodSelf loop

Page 22: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

GCNs PipelineHidden layer Hidden layer

Input Output

X = H(0)

H(1) H(2)

Z = H(n)

Initial feature representation of

nodes

Representation informed by nodes’

neighborhood

[Kipf and Welling, 2016]

… …

22

Page 23: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

GCNs PipelineHidden layer Hidden layer

Input Output

X = H(0)

H(1) H(2)

Z = H(n)

[Kipf and Welling, 2016]

… …

Extend GCNs for syntactic dependency trees

Initial feature representation of

nodes

Representation informed by nodes’

neighborhood

23

Page 24: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Outline

} Semantic Role Labeling} Graph Convolutional Networks (GCN)} Syntactic GCN for Semantic Role Labeling (SRL)} SRL Model} Exploiting Semantics in Neural Machine Translation with GCNs

24

Page 25: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Example

Lane disputed those estimates

NMOD

SBJ OBJ

[Marcheggiani and Titov, 2017]

25

Page 26: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Example

Lane disputed those estimates

NMOD

SBJ OBJ

⇥W

(1)

self

⇥W

(1)

self

⇥W

(1)

self

⇥W

(1)

self

ReLU(⌃·)ReLU(⌃·)ReLU(⌃·)ReLU(⌃·)

[Marcheggiani and Titov, 2017]

26

Page 27: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Example

Lane disputed those estimates

NMOD

SBJ OBJ

⇥W

(1)

self

⇥W

(1)

self

⇥W

(1)

self

⇥W

(1)

self

ReLU(⌃·)ReLU(⌃·)ReLU(⌃·)ReLU(⌃·)

⇥W(1)subj

⇥W(1)n

m

o

d

⇥W(1)

o

b

j

[Marcheggiani and Titov, 2017]

27

Page 28: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Example

Lane disputed those estimates

NMOD

SBJ OBJ

⇥W

(1)

self

⇥W

(1)

self

⇥W

(1)

self

⇥W

(1)

self

ReLU(⌃·)ReLU(⌃·)ReLU(⌃·)ReLU(⌃·)

⇥W(1)subj

⇥W(1)n

m

o

d

⇥W(1)

o

b

j

⇥W (1)o

b

j

0

⇥W(1)

n

m

o

d

0

⇥W(1)

subj

0

[Marcheggiani and Titov, 2017]

28

Page 29: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Example

Lane disputed those estimates

NMOD

SBJ OBJ

⇥W

(1)

self

⇥W

(1)

self

⇥W

(1)

self

⇥W

(1)

self

ReLU(⌃·)ReLU(⌃·)ReLU(⌃·)ReLU(⌃·)

⇥W(1)subj

⇥W(1)n

m

o

d

⇥W(1)

o

b

j

⇥W (1)o

b

j

0

⇥W(1)

n

m

o

d

0

⇥W(1)

subj

0

[Marcheggiani and Titov, 2017]

29

Page 30: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Example

⇥W

(1)

self

Lane disputed those estimates

NMOD

SBJ OBJ

⇥W(1)subj

⇥W

(1)

self

⇥W

(1)

self

⇥W

(1)

self

⇥W (1)o

b

j

0

⇥W(1)n

m

o

d

⇥W(1)

n

m

o

d

0

⇥W(1)

o

b

j

⇥W(1)

subj

0

ReLU(⌃·)ReLU(⌃·)ReLU(⌃·)ReLU(⌃·)

[Marcheggiani and Titov, 2017]

30

Page 31: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Example

⇥W

(1)

self

Lane disputed those estimates

NMOD

SBJ OBJ

⇥W(1)subj

⇥W

(1)

self

⇥W

(1)

self

⇥W

(1)

self

⇥W (1)o

b

j

0

⇥W(1)n

m

o

d

⇥W(1)

n

m

o

d

0

⇥W(1)

o

b

j

⇥W(1)

subj

0

ReLU(⌃·)ReLU(⌃·)ReLU(⌃·)ReLU(⌃·)

ReLU(⌃·)ReLU(⌃·)ReLU(⌃·)ReLU(⌃·)

⇥W

(2)

self ⇥W

(2)

self

⇥W

(2)

self

⇥W

(2)

self

⇥W(2)subj⇥W

(2)

subj

0

⇥W (2)o

b

j

0

⇥W(2)

o

b

j

⇥W

(2)n

m

o

d

⇥W(2)

n

m

o

d

0

Stacking GCNs widens the syntactic neighborhood

[Marcheggiani and Titov, 2017]

31

Page 32: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Syntactic GCNs

h(k+1)v = ReLU

0

@X

u2N (v)

W (k)L(u,v)h

(k)u + b(k)L(u,v)

1

A

[Marcheggiani and Titov, 2017]

32

Page 33: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Syntactic GCNs

h(k+1)v = ReLU

0

@X

u2N (v)

W (k)L(u,v)h

(k)u + b(k)L(u,v)

1

A

Syntactic neighborhood

[Marcheggiani and Titov, 2017]

33

Page 34: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Syntactic GCNs

Syntactic neighborhood

h(k+1)v = ReLU

0

@X

u2N (v)

W (k)L(u,v)h

(k)u + b(k)L(u,v)

1

A

Message

[Marcheggiani and Titov, 2017]

34

Page 35: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Syntactic GCNs

Syntactic neighborhood Self-loop is included in NMessages are direction and

label specific

h(k+1)v = ReLU

0

@X

u2N (v)

W (k)L(u,v)h

(k)u + b(k)L(u,v)

1

A

Message

[Marcheggiani and Titov, 2017]

35

Page 36: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

} Overparametrized: one matrix for each label-direction pair}

Syntactic GCNs

Syntactic neighborhood

W (k)L(u,v) = V (k)

dir(u,v)

Self-loop is included in NMessages are direction and

label specific

h(k+1)v = ReLU

0

@X

u2N (v)

W (k)L(u,v)h

(k)u + b(k)L(u,v)

1

A

Message

[Marcheggiani and Titov, 2017]

36

Page 37: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Edge-wise Gates

} Not all edges are equally important for the final task

[Marcheggiani and Titov, 2017]

37

Page 38: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Edge-wise Gates

} Not all edges are equally important for the final task} We should not blindly rely on predicted syntax

[Marcheggiani and Titov, 2017]

38

Page 39: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Edge-wise Gates

} Not all edges are equally important for the final task} We should not blindly rely on predicted syntax} Gates decide the “importance” of each message

Lane disputed those estimates

NMOD

SBJ OBJ

ReLU(⌃·) ReLU(⌃·)ReLU(⌃·)ReLU(⌃·)

g g g g g g g g g g

[Marcheggiani and Titov, 2017]

39

Page 40: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Edge-wise Gates

} Not all edges are equally important for the final task} We should not blindly rely on predicted syntax} Gates decide the “importance” of each message

Gates depend on nodes and edges Lane disputed those estimates

NMOD

SBJ OBJ

ReLU(⌃·) ReLU(⌃·)ReLU(⌃·)ReLU(⌃·)

g g g g g g g g g g

[Marcheggiani and Titov, 2017]

40

Page 41: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Outline

} Semantic Role Labeling} Graph Convolutional Networks (GCN)} Syntactic GCN for Semantic Role Labeling (SRL)} SRL Model} Exploiting Semantics in Neural Machine Translation with GCNs

41

Page 42: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Our Model

} Word representation} Bidirectional LSTM encoder} GCN Encoder} Local role classifier

[Marcheggiani and Titov, 2017]

42

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Word Representation

} Pretrained word embeddings} Word embeddings} POS tag embeddings} Predicate lemma embeddings

Lane disputed those estimates

wordrepresentation

[Marcheggiani and Titov, 2017]

43

Page 44: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

BiLSTM Encoder

} Encode each word with its left and right context} Stacked BiLSTM

Lane disputed those estimates

wordrepresentation

J layers BiLSTM

[Marcheggiani and Titov, 2017]

44

Page 45: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

GCNs Encoder

} Syntactic GCNs after BiLSTM encoder} Add syntactic information} Skip connections} Longer dependencies are captured

Lane disputed those estimates

wordrepresentation

J layers BiLSTM

dobj

nmodnsubj

K layers GCN

[Marcheggiani and Titov, 2017]

45

Page 46: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Semantic Role Classifier

Lane disputed those estimates

wordrepresentation

J layers BiLSTM

dobj

nmodnsubj

K layers GCN

A1Classifier

predicate representation

candidate argument representation

} Local log-linear classifier

p(r|ti, tp, l) / exp(Wl,r(ti � tp))

46

Page 47: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Experiments

} Data} CoNLL-2009 dataset - English and Chinese} F1 evaluation measure

} Model} Hyperparameters tuned on English development set} State-of-the-art predicate disambiguation models

[Marcheggiani and Titov, 2017]

47

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Ablation Experiments (Dev set)

82.7

83.3

81

82

83

84

85

English SRL w/o predicate disambiguation

BiLSTM GCN

[Marcheggiani and Titov, 2017]

48

75.2

77.1

73

74

75

76

77

78

Chinese SRL w/o predicate disambiguation

BiLSTM GCN

Page 49: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

English Test Set

87.3

87.7 87.7

88

86

87

88

89

FitzGerald et al. (2015) (global)

Roth and Lapata (2016) (global)

Marcheggiani et al. (2017, CoNLL) (local)

Ours (Bi-LSTM + GCN) (local)

SRL with predicate disambiguation

[Marcheggiani and Titov, 2017]

49

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English Out of Domain

75.2

76.1

77.7

77.2

74

75

76

77

78

FitzGerald et al. (2015) (global)

Roth and Lapata (2016) (global)

Marcheggiani et al. (2017, CoNLL) (local)

Ours (Bi-LSTM + GCN) (local)

SRL with predicate disambiguation

[Marcheggiani and Titov, 2017]

50

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English Test Set (Ensemble)

87.787.9

89.1

86

87

88

89

90

FitzGerald et al. (2015) (ensemble) Roth and Lapata (2016) (ensemble) Ours (Bi-LSTM + GCN) (ensemble)

SRL with predicate disambiguation

[Marcheggiani and Titov, 2017]

51

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Chinese Test Set

77.7

78.6

79.4

82.5

76

77

78

79

80

81

82

83

Zhao et al. (2009) (global) Bjö̈rkelund et al. (2009) (global)

Roth and Lapata (2016) (global)

Ours (Bi-LSTM + GCN) (local)

SRL with predicate disambiguation

[Marcheggiani and Titov, 2017]

52

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Syntactic Graph Convolutional Networks

53

} Fast and simple} Can be seamlessly applied to other tasks

Page 54: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Syntactic Graph Convolutional Networks

54

} Fast and simple} Can be seamlessly applied to other tasks

Graph Convolutional Encoders for Syntax-aware Machine TranslationJoost Bastings, Ivan Titov, Wilker Aziz, Diego Marcheggiani, Khalil Sima'an. In Proceedings of EMNLP, 2017.

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Syntactic Graph Convolutional Networks

55

} Fast and simple} Can be seamlessly applied to other tasks

Graph Convolutional Encoders for Syntax-aware Machine TranslationJoost Bastings, Ivan Titov, Wilker Aziz, Diego Marcheggiani, Khalil Sima'an. In Proceedings of EMNLP, 2017.

Improvements on English to German and

English to Czech translations

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Multi-document Question Answering

56

[De Cao et al., 2018]

• Nodes are entities and edges are co-reference links• Inference on a graph representing the documents collection

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Multi-document Question Answering

57

[De Cao et al., 2018]

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Syntactic Graph Convolutional Networks

58

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Syntactic Graph Convolutional Networks

59

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Syntactic Graph Convolutional Networks

60

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Outline

} Semantic Role Labeling} Graph Convolutional Networks (GCN)} Syntactic GCN for Semantic Role Labeling (SRL)} SRL Model} Exploiting Semantics in Neural Machine Translation with GCNs

61

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Motivations [Marcheggiani at al., 2018]

62

John gave his wonderful wife a nice present .

Giver

Thing given

Entity given to

John gave a nice present to his wonderful wife .

Giver

Entity given to

Thing given

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Motivations

SRL helps to generalize over different surface realizations of the same underlying “meaning”.

[Marcheggiani at al., 2018]

63

John gave his wonderful wife a nice present .

Giver

Thing given

Entity given to

John gave a nice present to his wonderful wife .

Giver

Entity given to

Thing given

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Motivations

64

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Motivations

65

Lost in translation

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Related work

} Semantics in statistical MT} [Wu and Fung, 2009]} [Liu and Gildea, 2010]} [Aziz et al., 2011]} ...

} Syntax in neural MT} [Sennrich and Haddow, 2016]} [Aharoni and Goldberg, 2017 ]} [Bastings et al., 2017]} …

} Semantics in neural MT} ???

[Marcheggiani at al., 2018]

66

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Predicate-argument encoding

67

John gave his wonderful wife a nice present

WA0

WA1WA2

WA0’ WA2’

WA1’

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Semantic GCN

Semantic GCN WA0

WA1WA2

WA0’ WA2’

WA1’

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Giver

Thing given

Entity given to

Page 68: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Our Model

} Standard sequence2sequence with attention} Semantic GCN encoder on top of a bidirectional RNN} RNN decoder

[Marcheggiani at al., 2018]

68

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Our model

John gave his wonderful wife a nice present

WA0

WA1WA2

WA0’ WA2’

WA1’

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

BiRNN/CNN

Semantic GCN

Semantic GCN WA0

WA1WA2

WA0’ WA2’

WA1’

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf<bos> John

John

+RNN

DECODERATTENTIONMECHANISM

[Marcheggiani at al., 2018]

69

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Our model

John gave his wonderful wife a nice present

WA0

WA1WA2

WA0’ WA2’

WA1’

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

BiRNN/CNN

Semantic GCN

Semantic GCN WA0

WA1WA2

WA0’ WA2’

WA1’

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf

Wse

lf<bos> John

John

+RNN

DECODERATTENTIONMECHANISM

[Marcheggiani at al., 2018]

70

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Experiments

} Data} WMT ‘16 English-German dataset (~4.5 million sentence pairs)} BLEU as evaluation measure

} Model} Hyperparameters tuned on News Commentary En-De (~226K sentence pairs)} GRU as RNN

[Marcheggiani at al., 2018]

71

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Results

23.323.9

20

21

22

23

24

25

26

BiRNN (Bastings et al. 2017)

BiRNN + Syntactic GCN

(Bastings et al. 2017)

BiRNN + Semantic GCN

BiRNN+Syntactic GCN +Semantic GCN

Full WMT 2016 English-German BLEU

[Marcheggiani at al., 2018]

72

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Results

23.323.9

24.5

20

21

22

23

24

25

26

BiRNN (Bastings et al. 2017)

BiRNN + Syntactic GCN

(Bastings et al. 2017)

BiRNN + Semantic GCN

BiRNN+Syntactic GCN +Semantic GCN

Full WMT 2016 English-German BLEU

[Marcheggiani at al., 2018]

73

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Results

23.323.9

24.5

20

21

22

23

24

25

26

BiRNN (Bastings et al. 2017)

BiRNN + Syntactic GCN

(Bastings et al. 2017)

BiRNN + Semantic GCN

BiRNN+Syntactic GCN +Semantic GCN

Full WMT 2016 English-German BLEU

[Marcheggiani at al., 2018]

74

+ 1.2 BLEU

Page 75: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Results

23.323.9

24.5

20

21

22

23

24

25

26

BiRNN (Bastings et al. 2017)

BiRNN + Syntactic GCN

(Bastings et al. 2017)

BiRNN + Semantic GCN

BiRNN+Syntactic GCN +Semantic GCN

Full WMT 2016 English-German BLEU

Semantics is helpful

[Marcheggiani at al., 2018]

75

+ 1.2 BLEU

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Results

23.323.9

24.524.9

20

21

22

23

24

25

26

BiRNN (Bastings et al. 2017)

BiRNN + Syntactic GCN

(Bastings et al. 2017)

BiRNN + Semantic GCN

BiRNN+Syntactic GCN +Semantic GCN

Full WMT 2016 English-German BLEU

[Marcheggiani at al., 2018]

76

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Results

23.323.9

24.524.9

20

21

22

23

24

25

26

BiRNN (Bastings et al. 2017)

BiRNN + Syntactic GCN

(Bastings et al. 2017)

BiRNN + Semantic GCN

BiRNN+Syntactic GCN +Semantic GCN

Full WMT 2016 English-German BLEU

[Marcheggiani at al., 2018]

77

+ 1.6 BLEU

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Results

23.323.9

24.524.9

20

21

22

23

24

25

26

BiRNN (Bastings et al. 2017)

BiRNN + Syntactic GCN

(Bastings et al. 2017)

BiRNN + Semantic GCN

BiRNN+Syntactic GCN +Semantic GCN

Full WMT 2016 English-German BLEU

Syntax and semantics are

complementary

[Marcheggiani at al., 2018]

78

+ 1.6 BLEU

Page 79: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

Analysis

John sold the car to Mark .

Seller Thing sold Buyer

The boy sitting on a bench in the park plays chess .

Thing sitting Location Player GameAM-LOC

The boy walking down the dusty road is drinking a beer .

Walker AM-DIR Drinker Liquid

SOURCE

SEM GCN

BiRNN John verkaufte das Auto nach Mark .

John verkaufte das Auto an Mark .

SEM GCN

BiRNN Der Junge zu Fuß die staubige Straße ist ein Bier trinken .

Der Junge , der die staubige Straße hinunter geht , trinkt ein Bier .

SEM GCN

BiRNN Der Junge auf einer Bank im Park spielt Schach .

Der Junge sitzt auf einer Bank im Park Schach .

SOURCE

SOURCE

[Marcheggiani at al., 2018]

79

BiRNN mistranslates “to” as “nach” (directionality)

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Analysis

John sold the car to Mark .

Seller Thing sold Buyer

The boy sitting on a bench in the park plays chess .

Thing sitting Location Player GameAM-LOC

The boy walking down the dusty road is drinking a beer .

Walker AM-DIR Drinker Liquid

SOURCE

SEM GCN

BiRNN John verkaufte das Auto nach Mark .

John verkaufte das Auto an Mark .

SEM GCN

BiRNN Der Junge zu Fuß die staubige Straße ist ein Bier trinken .

Der Junge , der die staubige Straße hinunter geht , trinkt ein Bier .

SEM GCN

BiRNN Der Junge auf einer Bank im Park spielt Schach .

Der Junge sitzt auf einer Bank im Park Schach .

SOURCE

SOURCE

[Marcheggiani at al., 2018]

80

BiRNN mistranslates “to” as “nach” (directionality)

Page 81: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

John sold the car to Mark .

Seller Thing sold Buyer

The boy sitting on a bench in the park plays chess .

Thing sitting Location Player GameAM-LOC

The boy walking down the dusty road is drinking a beer .

Walker AM-DIR Drinker Liquid

SOURCE

SEM GCN

BiRNN John verkaufte das Auto nach Mark .

John verkaufte das Auto an Mark .

SEM GCN

BiRNN Der Junge zu Fuß die staubige Straße ist ein Bier trinken .

Der Junge , der die staubige Straße hinunter geht , trinkt ein Bier .

SEM GCN

BiRNN Der Junge auf einer Bank im Park spielt Schach .

Der Junge sitzt auf einer Bank im Park Schach .

SOURCE

SOURCE

81

BiRNN mistranslates “to” as “nach” (directionality)

Analysis [Marcheggiani at al., 2018]

Page 82: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

John sold the car to Mark .

Seller Thing sold Buyer

The boy sitting on a bench in the park plays chess .

Thing sitting Location Player GameAM-LOC

The boy walking down the dusty road is drinking a beer .

Walker AM-DIR Drinker Liquid

SOURCE

SEM GCN

BiRNN John verkaufte das Auto nach Mark .

John verkaufte das Auto an Mark .

SEM GCN

BiRNN Der Junge zu Fuß die staubige Straße ist ein Bier trinken .

Der Junge , der die staubige Straße hinunter geht , trinkt ein Bier .

SEM GCN

BiRNN Der Junge auf einer Bank im Park spielt Schach .

Der Junge sitzt auf einer Bank im Park Schach .

SOURCE

SOURCE

Analysis [Marcheggiani at al., 2018]

82

Both translations are wrong,but the BiRNN’s one is grammatically correct

Page 83: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

John sold the car to Mark .

Seller Thing sold Buyer

The boy sitting on a bench in the park plays chess .

Thing sitting Location Player GameAM-LOC

The boy walking down the dusty road is drinking a beer .

Walker AM-DIR Drinker Liquid

SOURCE

SEM GCN

BiRNN John verkaufte das Auto nach Mark .

John verkaufte das Auto an Mark .

SEM GCN

BiRNN Der Junge zu Fuß die staubige Straße ist ein Bier trinken .

Der Junge , der die staubige Straße hinunter geht , trinkt ein Bier .

SEM GCN

BiRNN Der Junge auf einer Bank im Park spielt Schach .

Der Junge sitzt auf einer Bank im Park Schach .

SOURCE

SOURCE

Analysis [Marcheggiani at al., 2018]

83

Both translations are wrong,but the BiRNN’s one is grammatically correct

Page 84: Encoding Linguistic Structures with Graph Convolutional Networks · 2019-11-10 · @South England NLP Meetup. Structured (Linguistic) Priors ... 2017. Exploiting Semantics in Neural

John sold the car to Mark .

Seller Thing sold Buyer

The boy sitting on a bench in the park plays chess .

Thing sitting Location Player GameAM-LOC

The boy walking down the dusty road is drinking a beer .

Walker AM-DIR Drinker Liquid

SOURCE

SEM GCN

BiRNN John verkaufte das Auto nach Mark .

John verkaufte das Auto an Mark .

SEM GCN

BiRNN Der Junge zu Fuß die staubige Straße ist ein Bier trinken .

Der Junge , der die staubige Straße hinunter geht , trinkt ein Bier .

SEM GCN

BiRNN Der Junge auf einer Bank im Park spielt Schach .

Der Junge sitzt auf einer Bank im Park Schach .

SOURCE

SOURCE

Analysis [Marcheggiani at al., 2018]

84

Both translations are wrong,but the BiRNN’s one is grammatically correct

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Conclusion

} GCNs for encoding linguistic structures into NN} Semantics, coreference, discourse} Fast} Cheap

} State-of-the-art model for dependency-based SRL

} First to exploit semantics in NMT

85

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Roadmap

86

Including structured bias into neural NLP models

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Roadmap

87

Including structured bias into neural NLP models

Low-resource setting

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Roadmap

88

Including structured bias into neural NLP models

Low-resource settingLong-range dependencies

Document levelCross-document level

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Roadmap

89

Including structured bias into neural NLP models

Low-resource settingLong-range dependencies

Document levelCross-document level

Integrating external knowledge i.e., knowledge graphs

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Roadmap

90

Including structured bias into neural NLP models

Low-resource settingLong-range dependencies

Document levelCross-document level

Integrating external knowledge i.e., knowledge graphs

Thanks for your attention!