Matsushita Electric Industrial Co., Ltd.

Hirobumi Shinoki

Takamasa Oyama

Chuichi Kikuchi

Tetsuya Kinoshita

Tomoko Fujita

Noriyuki Enomoto

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.

Information retrieval system for retrieving a record of data including a

A plurality of characters arranged in a text are numbered in order of occurrence for each character type, and an occurrence number table in which one or more occurrence numbers are listed for each character type is prepared in an occurrence number preparing unit. Also, a set of two character types is defined as a character pattern, and a set of two occurrence numbers of two adjacent characters of which types correspond to one character pattern is defined as an occurrence number pattern. One or more occurrence number patterns respectively corresponding to one character pattern are arranged for each character pattern, and a list of occurrence number patterns is prepared as an index file in an index file preparing unit. Thereafter, a series of specified character patterns indicated by a key word is prepared, and a series of particular occurrence number patterns corresponding to the series of specified character patterns is selected on condition that a series of particular characters indicated by the series of particular occurrence number patterns agrees with the particular character stream. Therefore, because the characters of the text is converted to the occurrence number patterns and all occurrence number patterns are not searched, a searching operation can be performed at a high speed.

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Yokohama, Japan

Hirobumi Shinoki