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Parallel Tools for Natural Language Processing Mark Brigham Melanie Goetz Andrew Hogue 6.338 / 18.337 - March 16, 2004
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Consider the sentence: “John ate the cookie on the table” We want to: –Tag the sentence with parts of speech –Group the words by phrase Sentence Parsing
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… Context Free Grammars Recursive set of rules Defines what syntactic structure can be applied to a phrase or word Top-level rule S defines the sentence S→NP VP NP→Det N NP→NP PP VP→VP PP VP→V NP N→‘cookie’ N→‘table’ Det→‘the’ V→‘ate’
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Context Free Grammars Applying a CFG to a sentence creates a parse-tree for that sentence
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Context Free Grammars Top-down parse
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Context Free Grammars Bottom-up parse Parallelizable!
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Ambiguity More than one parse for a single sentence!
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Parallelization Bottom-up rule application appropriate for parallel processing Ambiguous parses also parallelizable Long, complex sentences may be most interesting Proust?
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Chart Parsing Create a matrix where entries correspond to words/phrases If there is a valid CFG parse of a phrase [i,j], add it to that matrix cell A cell [i,j] may only depend on other cells [m,n] where m < i and n < j.
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John ate the cookie on the table John ate the cookie on the table
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John ate the cookie on the table John ate the cookie on the table
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John ate the cookie on the table John ate the cookie on the table
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John ate the cookie on the table John ate the cookie on the table
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John ate the cookie on the table John ate the cookie on the table
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John ate the cookie on the table John ate the cookie on the table
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John ate the cookie on the table John ate the cookie on the table
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John ate the cookie on the table John ate the cookie on the table
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John ate the cookie on the table John ate the cookie on the table
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John ate the cookie on the table John ate the cookie on the table
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John ate the cookie on the table John ate the cookie on the table
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John ate the cookie on the table John ate the cookie on the table
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John ate the cookie on the table John ate the cookie on the table
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John ate the cookie on the table John ate the cookie on the table
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John ate the cookie on the table John ate the cookie on the table
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John ate the cookie on the table John ate the cookie on the table
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John ate the cookie on the table John ate the cookie on the table
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John ate the cookie on the table John ate the cookie on the table
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Other Tools Considering parallelizing other NLP tools Word-stemming: Multiple finite state automata applied to a single word in parallel Automated part-of-speech recognition on large corpora
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