Lexicalized Tree-Adjoining Grammars (LTAG) - ad-teaching.infor...

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LTAG-Spinal Parser - Tests Test data: 2401 sentences from section 23 of the Penn Treebank Test system of Shen and Joshi (2005): 2 × 1.13 GHz Pentium III, 2 GB RAM By varying some settings of their algorithm, they get: sen/sec f-score (%) 0.79 88.7 . . 0.07 94.2 Our test system (stromboli): 16 × 2.80 GHz Xeon X5560, 35 GB RAM I performed two series of measurements: • default settings • settings closer to S&J sen/sec f-score (%) 10.20 3.22 50 / 52
Conclusion TAG: a grammar formalism related to CFG, but more powerful Very interesting from the theoretical point of view (mathematical and linguistical) Parsable in polynomial time, but with a high exponent: O(n 6 ) Some recent research focuses on a subset, LTAG-spinal. 51 / 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 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: LTAG-Spinal Parser Graphical repres

Lexicalized Tree-Adjoining Grammars (LTAG) - ad-teaching.infor...

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