An Efficient Natural Language Processing System Specially Designed for the Chinese Language

In this paper an efficient natural language processing system specially designed for the Chinese language is presented. The center of the present system is a bottom-up chart parser with head-driven operation; i.e., phrases are built up by starting with their heads and adjoining constituents to the left or right of the heads instead of strictly from left to right. In this way many more unnecessary searching actions can be effectively eliminated. The present system also includes several efficient approaches such as a direction-selective chart to simplify the control of the head-driven operation; a heuristic scheduling policy and a bidirectional look-ahead approach to eliminate many unnecessary searching actions, and an improved raise-bind mechanism combined with check rules to treat the difficult problems of movement transformations and empty categories and to simplify the design of grammar rules. The present design is based on careful consideration of some special syntactic phenomena of the Chinese language, such as head-final and head-initial structures and empty categories. A prototype of the present system has been successfully implemented and extensive experiments have been performed. In the test results significant improvement in the efficiency in processing many very complicated Chinese sentences has been observed. The detailed discussion on the various approaches, the overall system design, and the experimental results will all be presented in this paper.