## Two monolingual parses are better than one (synchronous parse (2010)

Venue: | In Proc. of HLT-NAACL |

Citations: | 4 - 2 self |

### BibTeX

@INPROCEEDINGS{Dyer10twomonolingual,

author = {Chris Dyer},

title = {Two monolingual parses are better than one (synchronous parse},

booktitle = {In Proc. of HLT-NAACL},

year = {2010}

}

### OpenURL

### Abstract

We describe a synchronous parsing algorithm that is based on two successive monolingual parses of an input sentence pair. Although the worst-case complexity of this algorithm is and must be O(n6) for binary SCFGs, its average-case run-time is far better. We demonstrate that for a number of common synchronous parsing problems, the two-parse algorithm substantially outperforms alternative synchronous parsing strategies, making it efficient enough to be utilized without resorting to a pruned search. 1

### Citations

477 | Stochastic inversion transduction grammars and bilingual parsing of parallel corpora
- Wu
- 1997
(Show Context)
Citation Context ...cells involves considering two split points (one source, one target), it is not hard to see that this algorithm runs in time O(n 6 ). 3 Generalizing the algorithm to higher rank grammars is possible (=-=Wu, 1997-=-), as is converting a grammar to a weakly equivalent binary form in some cases (Huang et al., 2009).2.2 Parsing, intersection, and composition We motivate an alternative conception of the synchronous... |

413 | Hierarchical phrase-based translation
- Chiang
- 2007
(Show Context)
Citation Context ...peration is carried out using a standard monolingual parsing algorithm, such as Earley’s or CKY. In the experiments below, since we use ɛ-free grammars, we use a variant of CKY for unrestricted CFGs (=-=Chiang, 2007-=-). Once the first composition is done, the resulting parse forest must be converted into a CFG representation that the second parser can utilize. This is straightforward to do: each node becomes a uni... |

122 |
On formal properties of simple phrase structure grammars
- Bar-Hillel, Perles, et al.
- 1964
(Show Context)
Citation Context ...d composition We motivate an alternative conception of the synchronous parsing problem as follows. It has long been appreciated that monolingual parsing computes the intersection of an FSA and a CFG (=-=Bar-Hillel et al., 1961-=-; van Noord, 1995). That is, if S is an FSA encoding some sentence s, intersection of S with a CFG, G, results in a parse forest which contains all and only derivations of s, that is L(S) ∩ L(G) ∈ {{s... |

84 |
An improved context-free recognizer
- GRAHAM, HARRISON, et al.
- 1980
(Show Context)
Citation Context ...mar during this traversal as well. Analysis. Monolingual parsing runs in worst case O(|G| · n3 ) time, where n is the length of the input being parsed and |G| is a measure of the size of the grammar (=-=Graham et al., 1980-=-). Since the grammar term is constant for most typical parsing applications, it is generally not considered carefully; however, in the two-parse algorithm, the size of the grammar term for the second ... |

76 |
Syntax-directed transduction
- Lewis, Stearns
- 1968
(Show Context)
Citation Context ...zed without resorting to a pruned search. 1 Introduction Synchronous context free grammars (SCFGs) generalize monolingual context-free grammars to generate strings concurrently in pairs of languages (=-=Lewis and Stearns, 1968-=-) in much the same way that finite state transducers (FSTs) generalize finite state automata (FSAs). 1 Synchronous parsing is the problem of finding the best derivation, or forest of derivations, of a... |

55 | Forest Rescoring: Faster Decoding with Integrated Language Models
- Huang, Chiang
- 2007
(Show Context)
Citation Context ... with the two-parse algorithm but required more than 1 week with the baseline algorithm. 13 “Hiero” grammars. An alternative approach to computing a synchronous parse forest is based on cube pruning (=-=Huang and Chiang, 2007-=-). While more commonly used to integrate a target m-gram LM during decoding, Blunsom et al. (2008), who required synchronous parses to discriminatively train 10 How tight these bounds are depends on t... |

37 | Better word alignments with supervised ITG models
- Haghighi, Blitzer, et al.
- 2009
(Show Context)
Citation Context ...rge-scale learning applications infeasible. The usual solution is to use a heuristic search that avoids exploring edges that are likely (but not guaranteed) to be low probability (Zhang et al., 2008; =-=Haghighi et al., 2009-=-). In this paper, we derive an alternative synchronous parsing algorithm starting from a conception of parsing with SCFGs as a composition of binary relations. This enables us to factor the synchronou... |

29 | Hierarchical phrase-based translation with weighted finite state transducers - Iglesias, Gispert, et al. - 2009 |

24 | Binarization of synchronous context-free grammars. Computational Linguistics
- Huang, Zhang, et al.
- 2008
(Show Context)
Citation Context ...see that this algorithm runs in time O(n 6 ). 3 Generalizing the algorithm to higher rank grammars is possible (Wu, 1997), as is converting a grammar to a weakly equivalent binary form in some cases (=-=Huang et al., 2009-=-).2.2 Parsing, intersection, and composition We motivate an alternative conception of the synchronous parsing problem as follows. It has long been appreciated that monolingual parsing computes the in... |

24 | Bayesian learning of non-compositional phrases with synchronous parsing
- Zhang, Quirk, et al.
- 2008
(Show Context)
Citation Context ... ) run-time makes large-scale learning applications infeasible. The usual solution is to use a heuristic search that avoids exploring edges that are likely (but not guaranteed) to be low probability (=-=Zhang et al., 2008-=-; Haghighi et al., 2009). In this paper, we derive an alternative synchronous parsing algorithm starting from a conception of parsing with SCFGs as a composition of binary relations. This enables us t... |

23 | Some computational complexity results for synchronous context-free grammars
- Satta, Peserico
- 2005
(Show Context)
Citation Context ...escribes a bottom-up O(n 6 ) synchronous parsing algorithm for ITGs, a binary SCFG with a restricted form. For general grammars, the situation is even worse: the problem has been shown to be NP-hard (=-=Satta and Peserico, 2005-=-). Even if we restrict ourselves to binary ITGs, the ∗ This work was supported in part by the GALE program of DARPA, Contract No. HR0011-06-2-001. The author wishes to thank Philip Rensik, Adam Lopez,... |

21 | The intersection of finite state automata and definite clause grammars - Noord - 1995 |

20 |
Probabilistic inference for machine translation
- Blunsom, Osborne
- 2008
(Show Context)
Citation Context ...ing as two composition operations has both conceptual and practical benefits. The two-parse strategy can outperform both the ITG parsing algorithm (Wu, 1997), as well as the ‘cube-parsing’ technique (=-=Blunsom et al., 2008-=-). The latter result points to a connection with recent work showing that determinization of edges before LM integration leads to fewer search errors during decoding (Iglesias et al., 2009). Our resul... |

3 | N-way composition of weighted finite-state transducers - Allauzen, Mohri - 2009 |