Natural language processing and knowledge

Summary form only given. Natural language processing (NLP) requires varieties of knowledge. When we consider about man-machine dialogue we have to prepare lots of knowledge, and also strong inference functions such as logical inference and common sense reasoning. In this paper the author explains some new developments in knowledge for computational linguistics, then discuss about what kind of knowledge is required for a dialogue system. Information retrieval on the Web is an important technology. Estimating the confidence degree of information is a very difficult problem. The author discusses some possible ways of estimating the confidence degree of information. Natural language processing technologies as well as logical and common sense reasoning are involved in the estimation.