System and method for parsing natural language by unifying lexical features of words
First Claim
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1. A method for recognizing a sentence having a plurality of words, performed by a computer and comprising the steps of:
- (a) accepting a predefined grammar having terminal and non-terminal elements for defining allowable sentence structues;
(b) accepting a predefined lexicon having entries for defining terminal elements of the grammar in terms of linguistic or semantic features;
(c) predicting valid next lexical entries for any current partial sentences according to the grammar;
(d) reading input words;
(e) comparing features of the input words with the features of the valid next lexical entries;
(f) rejecting input words which have features which do not match valid next lexical entries;
(g) accepting input words which have features which match a valid next lexical entry;
(h) generating partial sentences by combining accepted input words consistent with the grammar and lexicon;
(i) unifying the lexical features of the words forming the partial sentences so that the partial sentences are self-consistent with respect to such features; and
(j) repeating steps (c) through (i) until a complete sentence is formed as defined in the grammar.
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Abstract
A method for parsing for natural languages includes a grammar and a lexicon. A knowledge base may be used to define elements in the lexicon. A processor receives single words input by a user and adds them to a sentence under construction. Valid next words are predicted after each received input word. The preferred system has two major components: a parser and a predictor. The predictor accesses only the lexicon and the knowledge base, if one is used, to determine the valid next input words. The parser constructs sentences which are valid according to the grammar out of words accepted by the predictor.
248 Citations
19 Claims
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1. A method for recognizing a sentence having a plurality of words, performed by a computer and comprising the steps of:
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(a) accepting a predefined grammar having terminal and non-terminal elements for defining allowable sentence structues; (b) accepting a predefined lexicon having entries for defining terminal elements of the grammar in terms of linguistic or semantic features; (c) predicting valid next lexical entries for any current partial sentences according to the grammar; (d) reading input words; (e) comparing features of the input words with the features of the valid next lexical entries; (f) rejecting input words which have features which do not match valid next lexical entries; (g) accepting input words which have features which match a valid next lexical entry; (h) generating partial sentences by combining accepted input words consistent with the grammar and lexicon; (i) unifying the lexical features of the words forming the partial sentences so that the partial sentences are self-consistent with respect to such features; and (j) repeating steps (c) through (i) until a complete sentence is formed as defined in the grammar. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system, having a grammar and a lexicon, for recognizing a natural language sentence having a plurality of words, comprising:
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input means for reading words; a parser comprising; means for retrieving rules from said grammar for combining words into partial sentences, means for generating sets of a valid next elements for the partial sentences according to said rules, and means for determining whether the partial sentences are complete as defined by said rules; and a predictor coupled to said input means, comprising; means for retrieving features from said lexicon, means for predicting the features of said valid next elements, means for comparing words read by said input means with words in said lexicon, means for rejecting words having features supplied by said lexicon which are not consistent with said predicted features of a valid next element, and means for unifying lexical features of the words forming said partial sentences so that said partial sentences are self-consistent with respect to such lexical features. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A method for recognizing a sentence having a plurality of words, performed by a computer and comprising the steps of:
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(a) accepting lexical features for words; (b) predicting a set of valid next input words according to a grammar; (c) reading an input word; (d) for a valid input word, appending the input word to a partial sentence to generate a new partial sentence; (e) unifying the lexical features of the words forming the new partial sentence so that the new partial sentence is self-consistent with respect to such lexical features; and (f) repeating steps (b) through (e) until a complete sentence is formed according to the grammar. - View Dependent Claims (15)
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16. A system, having a grammar and a lexicon, for parsing a natural language sentence having a plurality of words, comprising:
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input means for reading words; means for retrieving rules from said grammar; means for retrieving features from said lexicon; means coupled to said input means and said feature retrieving means for instantiating the features of words read by said input means at a sentence creation time; and means for combining the words into sentences according to said rules retrieved from said grammar. - View Dependent Claims (17, 18, 19)
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Specification