Patent ID: 7509314

Claim:
A document retrieval system for retrieving a document from a set of documents according to one or more terms received as search conditions submitted by a user, the terms that can be received including both numeric terms, which include numeric values, and non-numeric terms, which do not include numeric values, the document retrieval system comprising: a first processor for generating at least one item of index information for each document in the set of documents, the index information generated for the documents including both numeric term index information and non-numeric term index information, the non-numeric term index information including information about frequency of occurrence of non-numeric terms in the document, the numeric term index information including information about types and numeric values of numeric terms in the document; a memory unit for storing the index information generated by the first processor; a second processor for examining each numeric term received as a search condition, determining its type, and generating numeric search information indicating the type and numeric value of the numeric term; a third processor for using the non-numeric term index information generated by the first processor to calculate, for each document in the set of documents including a non-numeric term received as a search condition, a first numeric quantity having a single numeric value indicating a goodness of fit between the non-numeric term and the document; a fourth processor for using the numeric term index information generated by the first processor and the numeric search information generated by the second processor from a numeric term received as a search condition to calculate, for each document in the set of documents including a numeric term of the same type as the numeric term received as the search condition, by comparing numeric values of the numeric terms, a second numeric quantity having a single numeric value indicating a goodness of fit between the numeric term received as the search condition and the document, closer numeric values indicating better fits; a fifth processor for calculating, for a document in the set of documents, a third numeric quantity indicating a goodness of fit between the document and the one or more terms received as search conditions, the third numeric quantity being calculated from the first and second numeric quantities; and an output unit for sending information for displaying a list of documents from the set of documents to the user according to the third numeric quantity.