Symbol string conversion methods and speech recognition method using the symbol string conversion method, and speech recognition apparatus using the symbol string conversion unit and its symbol string conversion equipment

摘要

PPROBLEM TO BE SOLVED: To reduce computational quantity for performing the minimum cost search in a symbol string transduction method. PSOLUTION: A symbol string transduction method is disclosed for outputting an output symbol string corresponding to the state transition process of a WFST of a post stage in which the cumulative value of weights to state transitions which are to be applied respectively to the WFSTs of the preceding stage and the post stage of a symbol string transducing part become the minimum. A state transition process in which the cumulative weights become the minimum in possible state transition processes in the WFST of the post stage at the time when cumulative weights to hypothesis which expresses one state transition process of the WFST of the preceding stage and the output symbol string in the state transition process of the hypothesis are made the input symbol string of the WFST of the post stage is calculated while reading symbols one by one. The cumulative weights are corrected by adding the cumulative weights to the cumulative weights of the hypothesis and, at the point of time when all of input symbol strings are read, when the hypothesis in which the cumulative weights are the minimum and an output symbol string corresponding to the state transition process of the hypothesis are made the input symbol string of the WFST of the post stage, the output symbol string to the state transition process in which the cumulative weights become the minimum in possible state transition processes in the WFST of the post stage is made a transduced result. PCOPYRIGHT: (C)2005,JPO&NCIPI