Patent ID: 7653623

Claim:
An information searching apparatus for searching documents arranged in a hierarchical manner, the apparatus comprising: an index memory storing indexes of documents to be searched, each index containing keywords extracted from the corresponding document in association with a locator of that document; at least one processing device executing a first search module that searches the index memory upon receipt of a search request specifying a plurality of search keywords from a client device, to find documents whose corresponding indexes contain at least one of the specified search keywords, and identifies the found documents as tentative search results; a categorizer that determines to which group the tentative search result should belong, according to predefined rules; a second search module that searches an upper hierarchical level in the same group of the tentative search result to find a document containing at least one of the specified search keywords; a group order determiner that gives a higher display priority to the group in which the second search module has found the upper-level document; a third search module that determines display priorities of the documents within each of the groups according to rarity of the search keywords in the documents by giving a higher display priority to a document containing a rarer search keyword, wherein the third search module calculates a rarity score of each search keyword as a product of a total number of instances of each search keyword and a number of documents containing that search keyword, a search keyword with a smaller rarity score having a higher rarity; and a search result sender that extracts the locator of each search result from the index memory and, based on association between the groups and the extracted locators, rearranges the locators in descending order of the display priority before sending the locators to the client device for being displayed.