Patent ID: 7769771

Claim:
A document search apparatus comprising a processor coupled to a memory, and further comprising: a search request input to input a search request including a keyword set; a user interface to cause a display to display an initial search result to a user, the initial search result comprising a first retrieved document set retrieved from a plurality of documents stored in a document database using the keyword set of the search request; an extension word extractor to extract an extension word set from a seed document set, the seed document set being selected by the user from the first retrieved document set of the initial search result; a database manager to search through the plurality of documents stored in the document database for a second retrieved document set using the keyword set of the search request and the extension word set, wherein a first retrieved document of the first retrieved document set is displayed as a symbol having a position on a coordinate system, the position being defined by a relevance value of the first retrieved document of the first retrieved document set, and at least one attribute value of the first retrieved document of the first retrieved document set being converted to a numerical value when the at least one attribute value of the first retrieved document of the first retrieved document set is not expressed in a form of the numerical value; and wherein the first retrieved document is classified into a group of a plurality of groups according to the relevance value, and a weighting factor is assigned to each group of the plurality of groups.