Document matching degree operating system, document matching degree operating method and document matching degree operating program

摘要

In the present invention, a document matching degree indicating a matching degree of a target document with one or more search terms is calculated based on information in a plural documents information storing part, by calculating a TF term reflecting a frequency of the input search term in the target document and an IDF term reflecting an importance of the input search term in the target document, and from the TF term and the IDF term for each search term. Then there is calculated an expectation value of a number of appearances of a search term t in a target document d, by approximating the document set σ(t) by an appearing document set κ(t), and there is reflected, in the TF term, a disagreement of the expectation value with an actual number of appearances of the search term t in the target document d.