Development of Understanding System for Scientific and Technical Documents

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The goal of this project is to develop an understanding system for scientific and technical documents, such as INSPEC database. This goal requires us to develop techniquies of converting sentences into the first order formulas where the predicate symbols are verbs and the terms are noun phrases. We therefore addressed the problems of determination of structure of verb phrases and identification of ranges of noun phrases, and achieved the following resuls.(1) We developed a method of determining the verb phrases which is based on the ratio of the frequencies of a word in a abstract and key phrases.(2) Noun phrases can be considered to be composed of simple noun phrases, each of which consists of a head noun and its prepositional modifiers. We developed method of identifying head nouns and prepositional modifiers.(3) Traditionally the above mentioned identification was carried out by using parts-of-speech information which may contain lexical ambiguities. We showed the method of (2) is better than the traditional method by experments.(4) Using the identification method of (2) we developed a method of indetifying the ranges of simple noun phrases.