Lexicalized Tree-Adjoining Grammars (LTAG) - ad-teaching.infor...
Lexicalized Tree-Adjoining Grammars (LTAG) - ad-teaching.infor... Lexicalized Tree-Adjoining Grammars (LTAG) - ad-teaching.infor...
Tree Traversal The algorithm will traverse every eligible derived tree (Euler tour) while scanning the input string from left to right. Start End A Left context, already traversed Right context, to be traversed B C D A E F G H I 30 / 52
Recognizing Adjunction But the algorithm never builds derived trees! It only uses the elementary trees of the input grammar. Suppose that the following adjunction took place: A A = A (α) (β) (γ) w 1 w 5 A A w 1 w 3 w 5 w 2 w w 4 2 w 4 w 3 We need to traverse the derived tree γ but only have α and β at our disposal. 31 / 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: TAG Parsing Parser: Given a string
- 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
<strong>Tree</strong> Traversal<br />
The algorithm will traverse every eligible derived tree (Euler tour)<br />
while scanning the input string from left to right.<br />
Start<br />
End<br />
A<br />
Left context,<br />
alre<strong>ad</strong>y traversed<br />
Right context,<br />
to be traversed<br />
B<br />
C<br />
D<br />
A<br />
E F G H I<br />
30 / 52
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