Patent ID: 7392175

Claim:
A method of evaluating a document set commonality for a document set including a plurality of documents each having one or more document segments, the commonality indicating a degree to which topics of the individual documents of the document set are common, the method comprising: (a) generating for each of the document segments, a document segment vector in which components corresponding to terms appearing in the document segment assume a value “1” (one), and the other components assume a value “0” (zero); (b) generating for each of the documents of the document set a co-occurrence matrix from the document segment vectors; (c) generating a common co-occurrence matrix having rows and columns in which components have values defined as products of values of components of the same rows and the same columns of the co-occurrence matrices; and (d) evaluating the document set commonality on the basis of a sum of either all the components or diagonal components of the common co-occurrence matrix.