Information retrieval system for retrieving a record of data including a

Abstract

A division code is added to both ends of a group of pieces of data registered in an item of a data record L and between each pair of adjacent data, so that a piece of code-added data is produced. Thereafter, a character chain pattern (C1,C2) of each pair of adjacent characters C1 and C2 in the code-added data is prepared, an occurrence frequency Fi of each character Ci in each piece of data H is calculated, and character chain information (F1,F2,H,L) corresponding to each character chain pattern (C1,C2) is prepared. Therefore, a index file in which pieces of character chain information prepared for the same item of a plurality of data records are listed is prepared. When a keyword is input by a user, the division code is added to both ends of the keyword to produce a code-added keyword, and a series of keyword character chain patterns is prepared from the code-added keyword in the same manner. Thereafter, a series of particular character chain information (F1,F2,H,L) corresponding to the series of keyword character chain patterns on condition that F2 of first information equals to F1 of second information following the first information and data numbers H and record numbers L are respectively the same value. Therefore, a particular data record L in which a piece of particular data H including the keyword is registered can be quickly retrieved.