Patent ID: 7243092

Claim:
A computer-implemented method comprising: extracting terms from a plurality of electronic documents; ranking the extracted terms using two or more term ranking algorithms; aggregating rankings of the ranked extracted terms to produce first aggregate rankings, each of the rankings resulting from one of the two or more ranking algorithms; selecting terms from the extracted terms, the selected terms having the first aggregate rankings above a pre-determined threshold; generating term pairs from the selected terms; ranking terms in each term pair based on a relative specificity of the selected terms using two more term pair ranking algorithms; aggregating the ranks of the terms in each term pair to produce second aggregate rankings, each of the ranks resulting from the two or more term pair ranking algorithms; selecting term pairs having the second aggregate rankings above a pre-determined threshold; generating a term hierarchy from the selected term pairs; assigning documents to nodes of the term hierarchy based on a number of terms within a branch of the term hierarchy associated with each node that match terms extracted from each document; and storing assignments of the documents to the nodes to a memory for retrieval of one or more documents responsive to a search query.