Keyword extraction apparatus, keyword extraction method, and computer readable recording medium storing keyword extraction program

Abstract

Disclosed is a keyword extraction apparatus and method capable of overcoming a problem in the conventional automatic keyword extraction wherein character strings in a sentence to be processed are employed, as they are, to assign a document with an index in terms of keywords; hence words having the similar meaning but different expressions in written language cannot be retrieved. The keyword extraction apparatus comprises technical term storage means for storing technical terms with proper expressions and different expressions thereof, and basic word storage means for storing general basic words of high frequency. Technical-term segmentation point setting means cuts out a range of any of the technical terms stored in technical term storage means from an input sentence. When the cut-out technical term is written in a different expression, the different expression is replaced by a corresponding proper expression in proper expression replacing means. Character-type segmentation point setting means detects a difference in character type in the input sentence. Basic-word segmentation point setting means cuts out, from the input sentence, a range of any of the basic words stored in the basic word storage means. Partial character string cutting means cuts out, as keywords, all relevant partial character strings based on segmentation points set by the technical-term segmentation point setting means, the character-type segmentation point setting means and the basic-word segmentation point setting means.