DOCUMENT RETRIEVING METHOD, ITS EXECUTING DEVICE AND MEDIUM RECORDING ITS PROCESSING PROGRAM

摘要

PROBLEM TO BE SOLVED: To speed up the retrieval performance and also to minimize the increase of the total index sizes by producing an expanded partial character string adding a character string to a partial character string and an index corresponding to it when such a possibility that the partial character string corresponding to an index is retrieved is high. SOLUTION: An index size comparing program 116 compares the size of an index corresponding to the partial character string with a reference index size. A reference frequency comparing program 117 compares a reference frequency corresponding to an index in a reference frequency table 123 with a standard reference frequency. And, it is decided whether the possibility that the partial character string corresponding to the index is retrieved by an index retrieving program 120 is high. When the possibility that the partial character string is retrieved by the index retrieving program 120 is high, an n-gram increment program 118 produces an expanded partial character string adding a character string to the partial character string and an index corresponding to the expanded partial character string.