DOCUMENT RETRIEVAL DEVICE, DOCUMENT RETRIEVAL METHOD, PROGRAM, AND RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To provide a document retrieval device capable of obtaining an appropriate retrieved result for a retrieval request while hardly generating problems of retrieval omissions and excessive retrieval compared to the conventional case. SOLUTION: The document retrieval device obtains an appearing set of the same character string as a notation of a word extracted from a retrieval condition for a plurality of documents composed of the character strings expressed in a natural language, simultaneously obtains the appearing set in which the same word as the word extracted from the retrieval condition appears, and obtains an appearing degree for each word on the basis of the appearing sets. By obtaining a sufficiency degree on the basis of the appearing degree obtained for all the words extracted from the retrieval condition and selecting and outputting the document of the retrieved result corresponding to the sufficiency degree, the appropriate retrieved result for the retrieval condition is obtained.