Patent ID: 7225120

Claim:
A method of extracting an important term from an input document including one or plural document segments, comprising the steps of: (a) generating, for the respective document segments, document segment vectors having values relating to occurrence frequencies of terms occurring in the document segments as component values; (b) generating a square sum matrix from the document segment vectors to calculate eigenvectors and eigenvalues of the square sum matrix; (c) selecting and outputting a definite number of eigenvectors and eigenvalues of the square sum matrix; (d) generating, with respect to the terms in the input document, term vectors in which only components corresponding to the terms included in the items have a first binary value and the other components have a second binary value; (e) obtaining a measure of the importance of the terms by using the definite number of eigenvectors, the definite number of eigenvalues, and the term vectors; (f) selecting and outputting the important term of the input document by using the importance; (g) the square sum matrix is calculated as; S = ∑ m = 1 M ⁢ d m ⁢ d m T where: M=the number of the document segments, an m-th document segment vector is d m =(d m1 , . . . , d mN ) T and (m=1, . . . , M), and N=the number of terms, T denotes transpose of a vector, and d mn denotes a value relating to an occurrence frequency of an n-th term occurring in the document segments.