Patent ID: 8583436

Claim:
A word category estimation apparatus comprising: a storage storing a word category model which includes a word model indicating relationships between features of arcs that form a word category graph and an occurrence frequency of a word category, and an utterance model indicating relationships between a feature of an entire word category graph and the occurrence frequency of the word category, relationships between features of the respective arcs and occurrence frequencies of corresponding word categories, and includes information indicating, as features of each of the arcs, relationships with respective arcs that form the word category graph; and a word category estimation unit implemented at least in hardware of the apparatus and which receives a word category graph of a speech recognition hypothesis to be processed, computes, by referring to said word category model, scores representing occurrence frequencies of word categories corresponding to the arcs and the features of said word category model of the arcs that form the words category graph and of the entire word category graph, and outputs a word category sequence candidate based on the scores, wherein the feature of the entire word category graph includes a number of arcs of the entire word category graph, and an average number of branches of arcs of the entire word category graph, wherein the feature of the arcs that form the word category graph includes position information in the entire word category graph.