Patent Document ID: 7630992
Application ID: 11505654

Base Claim:
1. A method for generating a reduced rank approximation for information retrieval, comprising: forming on a computer a term-by-document matrix A, wherein the elements of the matrix A represent a plurality of terms within a plurality of documents, the documents related to a plurality of topics; estimating via the computer a plurality of singular values corresponding to at least one of the topics; identifying via the computer a plurality of actual singular values each having a corresponding singular vector associated with the matrix A; selecting via the computer a subset of the actual singular values based on actual singular values that correspond to at least one of the estimated singular values; and determining via the computer a set of singular vectors based on the selected singular values, wherein the singular vectors provide an index for use during information retrieval.

---

Claim 6:
6. The method of claim 1 , wherein the step of estimating singular values corresponding to a topic comprises the steps of: generating characteristic coefficients; forming a special characteristic polynomial based on the characteristic coefficients; and solving for the roots of the characteristic polynomial, wherein multiplying the roots by the number of documents related to the topic and then taking a square-root yields the estimated singular values.