Development of a Full Text Retrieval System based on Logical Structure of Documents

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The investigators have conducted research and development of a system with which users can retrieve documents from a full text database containing full documents such as academic papers. Results obtained were as follows: 1. Based on detailed analysis of retrieval requests for full text databases, they made detailed design of a formal notation DQL (Document Query Language) for describing retrieval and display requests efficiently according to the document type definition of SGML. 2. They designed a user system software which displays document structures and let users select elements with pointing devices and specify retrieval conditions and display instructions. The system w as developed on work-stations using graphical user interface systems. 3. They developed a server system software on a main frame computer which stores documents in a relational database management system by expressing the structure as binomial relations among elements and processes retrieval requests described in DQL. 4. They developed a communication method between sever and user systems and confirmed the functionality by experiments using LAN and ISDN. 5. They evaluated the overall performance, usability, retrieval precision and so on and considered on the problems and their solutions toward the practical use.Through evaluation, the necessity of performance improvement of the server system was revealed. Further investigation has made it clear that including referenced record identifiers within the binomial relation records is effective. It is the future issue to implement this method. The necessity for the user system to represent specified retrieval requests more understandably was also revealed. Several methods already proposed should be studied by experiments.As the result of the research, feasibility of the design concept and the implementation method of this system was confirmed, the approach to the existing problems was presented, and the reality of the full-fledged system was shown.