Leveraging back-off grammars for authoring context-free grammars
First Claim
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1. A method of refining a context-free grammar, the method comprising:
- generating backoff grammar rules from rules of an initial context-free grammar, each backoff grammar rule being generated based on at least one keyword identified from the initial context-free grammar; and
recursively modifying the initial context-free grammar using a computer processing unit, wherein recursively modifying comprises;
obtaining a relined context-free grammar by modifying the initial context-free grammar,during a first iteration, based at least in part on recognition of utterances using the backoff grammar rules;
determining a recognition efficiency of the refined context-free grammar and the hackoff grammar rules to the utterances; and
during each of at least one additional iteration, further modifying the refined context-free grammar based at least in part on recognition of utterances using the refined context free grammar and backoff grammar rules until the refined context-free grammar and the backoff grammar rules meet a threshold level of recognition efficiency.
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Abstract
A system and method of refining context-free grammars (CFGs). The method includes deriving back-off grammar (BOG) rules from an initially developed CFG and utilizing the initial CFG and the derived BOG rules to recognize user utterances. Based on a response of the initial CFG and the derived BOG rules to the user utterances, at least a portion of the derived BOG rules are utilized to modify the initial CFG and thereby produce a refined CFG. The above method can carried out iterativey, with each new iteration utilizing a refined CFG from preceding iterations.
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Citations
16 Claims
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1. A method of refining a context-free grammar, the method comprising:
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generating backoff grammar rules from rules of an initial context-free grammar, each backoff grammar rule being generated based on at least one keyword identified from the initial context-free grammar; and recursively modifying the initial context-free grammar using a computer processing unit, wherein recursively modifying comprises; obtaining a relined context-free grammar by modifying the initial context-free grammar,during a first iteration, based at least in part on recognition of utterances using the backoff grammar rules; determining a recognition efficiency of the refined context-free grammar and the hackoff grammar rules to the utterances; and during each of at least one additional iteration, further modifying the refined context-free grammar based at least in part on recognition of utterances using the refined context free grammar and backoff grammar rules until the refined context-free grammar and the backoff grammar rules meet a threshold level of recognition efficiency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An adaptive speech recognition system comprising:
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one or more computer processors; a language model component comprising a language model that includes a context-free grammar (CFG) and a plurality of back-off grammar (BOG) rules, the BOG rules each comprising a rule for producing a recognition result from a user utterance and being derived from one or more grammar rules of the CFG that specify words and patterns of words, wherein the language model component obtains recognition results, using at least one of the computer processors, for user utterances by processing the user utterances with the CFG during a first pass and then processing a portion of the use utterances that comprise out of grammar utterances with the BOG rules during a second pass; and a grammar refining component that iteratively modifies the language model, using at least one of the computer processors, based on a data indicator that identifies the most frequently occurring out of grammar utterances handled by the BOG rules, wherein modifying the language model comprises incorporating the most frequently occurring out of grammar utterances into the CFG. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification