Lexicalized Tree-Adjoining Grammars (LTAG) - ad-teaching.infor...
Lexicalized Tree-Adjoining Grammars (LTAG) - ad-teaching.infor... Lexicalized Tree-Adjoining Grammars (LTAG) - ad-teaching.infor...
Our Goal We want to generate syntax trees like this: S NP VP D N often VP the penguin V NP chases D the N elephant 2 / 52
Context-Free Grammars Definition (Context-Free Grammar) A context-free grammar (CFG) is a 4-tuple G = (N, T , P, S) where: N is a finite set of non-terminal symbols. T is a finite set of terminal symbols, N ∩ T = ∅. P ⊆ N × (N ∪ T ) ∗ is a finite set of production rules. S ∈ N is a specific start symbol. Example G = (N, T , P, S) where: N = {S, NP, D, N, VP, V} T = {often, chases, helps, the, penguin, elephant} P : S → NP VP NP → D N D → the N → penguin ∣ ∣ elephant VP → often VP ∣ ∣ V NP V → chases ∣ ∣ helps 3 / 52
- Page 1: Lexicalized Tree-Adjoining Grammars
- Page 5 and 6: Tree-Substitution Grammars Example
- Page 7 and 8: Outline 1 Why CFGs are not enough (
- Page 9 and 10: Cross-Serial Dependencies Example (
- 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
Our Goal<br />
We want to generate syntax trees like this:<br />
S<br />
NP<br />
VP<br />
D<br />
N<br />
often<br />
VP<br />
the<br />
penguin<br />
V<br />
NP<br />
chases<br />
D<br />
the<br />
N<br />
elephant<br />
2 / 52
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