Patent ID: 7194461

Claim:
A method of retrieving at least one of a desired document item and an information item from at least one of a plurality of document items and information items, items being identified by item index vectors, the method being performed in response to a query including plural query terms, the query terms being related to each other in Boolean logic form, the method comprising: transforming the query terms in Boolean logic form into a transformed vector form; retrieving the desired item information in response to similarity measurements of the transformed vector form of the query terms and the item index vectors; and outputting the retrieved desired item information to an output unit, wherein the transforming step comprises: (a) calculating a square sum matrix by the using a plurality of first index vectors, the first index vectors having components indicating the presence or absence of each of the plural query terms, the square matrix being calculated on the basis of all the first index vectors which are generated from said query; and (b) calculating eigenvectors and eigenvalues of the square sum matrix.