RETRIEVAL SYSTEM, INDEX PREPARATION APPARATUS, RETRIEVAL DEVICE, INDEX PREPARATION METHOD, RETRIEVAL METHOD, AND PROGRAM

摘要

PROBLEM TO BE SOLVED: To enable highly-accurate retrieval of string information stored in a computer.SOLUTION: A retrieval system 200 includes: a token division part 222 for dividing an input string to be retrieved into one or more tokens; a position definition part 232 for determining tokens registered as those to be excluded in calculating an appearance position to be excluded tokens, determining tokens not to be excluded to be headword tokens, and defining the appearance position with respect to the headword tokens; an information addition part 234 for adding positional information to the excluded tokens, the positional information of which the headword tokens followed by the excluded tokens are set as an original point; an indexing processing part 236 for, with respect to the tokens, identifying whether or not the excluded tokens follow thereto and indexing them. The retrieval system 200 additionally includes a retrieval processing part 250 for extracting a token array matching with not only a retrieval token array included in a phrase retrieval query but also the appearance position and the positional information therein, when retrieval processing considering the excluded tokens is required,.