Patent ID: 6678690
Filing Date: 2004-01-13
Classification: G06F,Y10S

Abstract:
A method for retrieving and/or ranking documents in a database, the documents including attribute data, said method comprising steps of:providing a document matrix from said documents, said matrix including numerical elements derived from said attribute data; providing a covariance matrix from said document matrix; executing singular value decomposition of said covariance matrix so as to obtain the following formula: K=VÂ·&Sgr;Â·VT, wherein K represents said covariance matrix, V represents the matrix consisting of eigenvectors, &Sgr; represents a diagonal matrix, and VT represents a transpose of the matrix V;reducing a dimension of said matrix V using predetermined numbers of eigenvectors included in said matrix V, said eigenvectors including an eigenvector corresponding to the largest singular value; reducing a dimension of said document matrix using said dimension reduced matrix V; and retrieving and/or ranking said documents in said database by computing a scalar product between said dimension reduced document matrix and a query vector, wherein said covariance matrix is computed by the following formula: K=Bâˆ’XbarÂ·XbarT, wherein K represents said covariance matrix, B represents a momentum matrix, Xbar represents a mean vector and XbarT represents a transpose of said mean vector.