Index of papers in Proc. ACL 2009 that mention

**subtrees**

Conclusion | The system reuses standard techniques for building projective trees by combining adjacent nodes (representing subtrees with adjacent yields), but adds a simple mechanism for swapping the order of nodes on the stack, which gives a system that is sound and complete for the set of all dependency trees over a given label set but behaves exactly like the standard system for the subset of projective trees. |

Introduction | This is not the case for the tree in Figure l, where the subtrees rooted at node 2 (hearing) and node 4 (scheduled) both have discontinuous yields. |

Transitions for Dependency Parsing | The fact that we can swap the order of nodes, implicitly representing subtrees , means that we can construct non-projective trees by applying |

Transitions for Dependency Parsing | LEFT-ARC; or RIGHT-ARC; to subtrees whose yields are not adjacent according to the original word order. |

subtrees is mentioned in 4 sentences in this paper.

Topics mentioned in this paper:

- dependency trees (16)
- dependency parsing (13)
- time complexity (7)

Model | This algorithm proceeds in top-down fashion by sampling individual split points using the marginal probabilities of all possible subtrees . |

Model | To do so directly would involve simultaneously marginalizing over all possible subtrees as well as all possible alignments between such subtrees when sampling upper-level split points. |

Model | For every pair of nodes n1 6 T1,n2 6 T2, a table stores the marginal probability of the subtrees rooted at m and 712, respectively. |

subtrees is mentioned in 4 sentences in this paper.

Topics mentioned in this paper:

- word-level (14)
- parallel sentences (12)
- part-of-speech (10)

The Acquisition of Bracketing Instances | From a binary bracketing instance, we derive a unary bracketing instance ((9,710,119)), ignoring the subtrees 7(cz-nj) and flog-+1.19). |

The Syntax-Driven Bracketing Model 3.1 The Model | These features are to capture the relationship between a source phrase 3 and 7(3) or 7(3)’s subtrees . |

The Syntax-Driven Bracketing Model 3.1 The Model | There are three different scenarios3: l) exact match, where 3 exactly matches the boundaries of 7(3) (figure 3(a)), 2) inside match, where 3 exactly spans a sequence of 7(3)’s subtrees (figure 3(b)), and 3) crossing, where 3 crosses the boundaries of one or two subtrees of 7(3) (figure 3(c)). |

The Syntax-Driven Bracketing Model 3.1 The Model | The source phrase 32 exactly spans two subtrees VV and AS of VP, therefore CBMF is “VP-I”. |

subtrees is mentioned in 4 sentences in this paper.

Topics mentioned in this paper:

- parse tree (14)
- phrase-based (14)
- BLEU (8)