tailieunhanh - Báo cáo khoa học: "Guiding an HPSG Parser using Semantic and Pragmatic Expectations"

1 Efficient natural language generation has been successfully demonstrated using highly compiled knowledge about speech acts and their related social actions. A design and prototype implementation of a parser which utilizes this same pragmatic knowledge to efficiently guide parsing is presented. Such guidance is shown to prune the search space and thus avoid needless processing of pragmatically unlikely constituent structures. INTRODUCTION The use of purely syntactic knowledge during the parse phase of natural language understanding yields considerable local ambiguity (consideration of impossible subeonstituents) as well global ambiguity (construction of syntactically valid parses not applicable to the socio-pragmatic context) | Guiding an HPSG Parser using Semantic and Pragmatic Expectations Jim Skon Computer and Information Science Department The Ohio State University Columbus OH 43210 USA Internet skon@ Abstract 1 Efficient natural language generation has been successfully demonstrated using highly compiled knowledge about speech acts and their related social actions. A design and prototype implementation of a parser which utilizes this same pragmatic knowledge to efficiently guide parsing is presented. Such guidance is shown to prune the search space and thus avoid needless processing of pragmatically unlikely constituent structures. INTRODUCTION The use of purely syntactic knowledge during the parse phase of natural language understanding yields considerable local ambiguity consideration of impossible subconstituents as well global ambiguity construction of syntactically valid parses not applicable to the socio-pragmatic context . This research investigates bringing socio-pragmatic knowledge to bear during the parse while maintaining a domain independent grammar and parser. The particular technique explored uses knowledge about the pragmatic context to order the consideration of proposed parse constituents thus guiding the parser to consider the best wrt the expectations solutions first. Such a search may be classified as a best-first search. The theoretical models used to represent the pragmatic knowledge in this study are based on Halliday s Systemic Grammar and a model of the pragmatics of conversation. The model used to represent the syntax and domain independent semantic knowledge is HPSG - Head-driven Phrase Structure Grammar. BACKGROUND Patten Geis and Becker 1992 demonstrate the application of knowledge compilation to achieve the rapid generation of natural language. Their mechanism is based on Halliday s systemic networks and on Geis theory of the pragmatics of conversation. A model of conversation using principled compilation of pragmatic knowledge and .