Lexicalized Tree-Adjoining Grammars (LTAG) - ad-teaching.infor...
Lexicalized Tree-Adjoining Grammars (LTAG) - ad-teaching.infor... Lexicalized Tree-Adjoining Grammars (LTAG) - ad-teaching.infor...
Outline 1 Why CFGs are not enough (for linguists) Generative capacity Lexicalization 2 Introduction to Tree-Adjoining Grammars 3 An Algorithm for Parsing TAGs 4 LTAG-Spinal Parser 8 / 52
Cross-Serial Dependencies Example (Swiss German; Shieber, 1985) b a b a . . . das mer em Hans es huus hälfed aastriiche . . . that we Hans DAT house ACC helped paint ‘. . . that we helped Hans paint the house’ a b a a b a . . . das mer d’chind em Hans es huus lönd hälfe aastriiche . . . that we the children ACC Hans DAT house ACC let help paint ‘. . . that we let the children help Hans paint the house’ This can be reduced to the copy language {ww | w ∈ {a, b} ∗ } which is not context-free. 9 / 52
- Page 1 and 2: Lexicalized Tree-Adjoining Grammars
- Page 3 and 4: Context-Free Grammars Definition (C
- Page 5 and 6: Tree-Substitution Grammars Example
- Page 7: Outline 1 Why CFGs are not enough (
- Page 11 and 12: Lexicalization Example (Lexicalized
- Page 13 and 14: Lexicalization Example (CFG which i
- Page 15 and 16: Outline 1 Why CFGs are not enough (
- Page 17 and 18: Initial Trees Definition (Initial T
- Page 19 and 20: Substitution Definition (Substituti
- Page 21 and 22: Adjunction Definition (Adjunction)
- Page 23 and 24: Adjunction Constraints Given TAG G
- Page 25 and 26: Lexicalization Example (strong lexi
- Page 27 and 28: Further Formal Properties of TAL Tr
- Page 29 and 30: TAG Parsing Parser: Given a string
- Page 31 and 32: Recognizing Adjunction But the algo
- Page 33 and 34: Dotted Tree We introduce the notion
- Page 35 and 36: Chart Items The algorithm stores in
- Page 37 and 38: Scan Operations Input string: c 1
- Page 39 and 40: Complete Operations 1 2 3 [γ, adr,
- Page 41 and 42: Recognizer Algorithm Algorithm (Rec
- Page 43 and 44: Complexity of Recognizer Given: n:
- Page 45 and 46: Recognizing Substitution Recognizer
- Page 47 and 48: LTAG-Spinal Parser LTAG-spinal: Rou
- Page 49 and 50: LTAG-Spinal Parser Graphical repres
- Page 51 and 52: Conclusion TAG: a grammar formalism
Outline<br />
1 Why CFGs are not enough (for linguists)<br />
Generative capacity<br />
Lexicalization<br />
2 Introduction to <strong>Tree</strong>-<strong>Adjoining</strong> <strong>Grammars</strong><br />
3 An Algorithm for Parsing TAGs<br />
4 <strong>LTAG</strong>-Spinal Parser<br />
8 / 52
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