EVALUATION OF DOCUMENT DIFFICULTY

A system and computer implemented method for estimating difficulty of a document includes retrieving a subject document from a storage, setting difficulty of each keyword included in the subject document to locality of the keyword in the subject document as an initial value, estimating, by a processor, difficulty of each subject document by a statistical processing of the difficulties of keywords included in the subject document, and updating the difficulty of each keyword based on the difficulty of each subject document depending on a significance value of the keyword in the subject document.