Patent ID: 7010519

Claim:
An computer apparatus for expanding a character string comprising: a character string dividing device to divide an entered character string into a plurality of partial character strings each having a plurality of characters, the character string being entered in order to search image information of documents; a similarity table previously storing groups of similar partial character strings, each of the groups of similar partial character strings each consisting of a plurality of characters and arranged in an order of magnitude of emergence probabilities in each group, each of the groups of similar partial character strings being derived from each of the plurality of partial character strings obtained from the character string dividing device by changing at least one of characters of each partial character string to a different character which is similar in shape; a referring device that refers to the similarity table to obtain each of the groups of the similar partial character strings; a search term expansion device to combine a plurality of similar partial character strings given by the referencing device into expanded words, each having a product of the emergence probabilities of the similar partial character strings, and store them in an expanded word table.