The document search device, the ngram index which designates ngram which

摘要

PROBLEM TO BE SOLVED: To provide a document retrieving device capable of expanding retrieval conditions even when an n-gram index is used.;SOLUTION: To a retrieval condition 10 to become a retrieval character string inputted from a user by a retrieval condition input part 21, a document ranking part 22 selects the set of suited documents out of a document file 23a in a document database 23. A word extracting part 24 extracts a word in the suited document by morpheme analysis or the like. A word ranking part 25 selects a word in the suited document corresponding to the degree of relation by an n-gram index 23b of the document database 23 and prepares new retrieval conditions by adding such words to the original retrieval conditions as words related to the retrieval conditions. On such new retrieval conditions, a suited document 30 is selected out of the document database 23 by the document ranking part 22 again and outputted by a document output part 26.;COPYRIGHT: (C)2002,JPO