A* parsing: Fast exact Viterbi parse selection.

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A* parsing: Fast exact Viterbi parse selection. (2002)

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by Dan Klein , Christopher D Manning

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95 - 4 self

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@TECHREPORT{Klein02a*parsing:,
    author = {Dan Klein and Christopher D Manning},
    title = {A* parsing: Fast exact Viterbi parse selection.},
    institution = {},
    year = {2002}
}

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Abstract

Abstract We present an extension of the classic A* search procedure to tabular PCFG parsing. The use of A* search can dramatically reduce the time required to find a best parse by conservatively estimating the probabilities of parse completions. We discuss various estimates and give efficient algorithms for computing them. On average-length Penn treebank sentences, our most detailed estimate reduces the total number of edges processed to less than 3% of that required by exhaustive parsing, and a simpler estimate, which requires less than a minute of precomputation, reduces the work to less than 5%. Unlike best-first and finite-beam methods for achieving this kind of speed-up, an A* method is guaranteed to find the most likely parse, not just an approximation. Our parser, which is simpler to implement than an upward-propagating best-first parser, is correct for a wide range of parser control strategies and maintains worst-case cubic time.

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