tailieunhanh - Báo cáo khoa học: "Growing Semantic Grammars"

A criticalpath in the development of natural language understanding (NLU) modules lies in the difficulty of defining a mapping from words to semantics: Usually it takes in the order of years of highly-skilled labor to develop a semantic mapping, the form of a semantic grammar, that is comprehensive enough for a given domain. Yet, due to the very nature of h u m a n language, such mappings invariably failto achieve fullcoverage on unseen data. | Growing Semantic Grammars Marsal Gavaldà and Alex Waibel Interactive Systems Laboratories Carnegie Mellon University Pittsburgh PA 15213 . marsal@ Abstract A critical path in the development of natural language understanding NLƯ modules lies in the difficulty of defining a mapping from words to semantics Usually it takes in the order of years of highly-skilled labor to develop a semantic mapping . in the form of a semantic grammar that is comprehensive enough for a given domain. Yet due to the very nature of human language such mappings invariably fail to achieve full coverage on unseen data. Acknowledging the impossibility of stating a priori all the surface forms by which a concept can be expressed we present Gsg an empathic computer system for the rapid deployment of NLU front-ends and their dynamic customization by non-expert end-users. Given a new domain for which an NLU front-end is to be developed two stages are involved. In the authoring stage Gsg aids the developer in the construction of a simple domain model and a kernel analysis grammar. Then in the run-time stage Gsg provides the enduser with an interactive environment in which the kernel grammar is dynamically extended. Three learning methods are employed in the acquisition of semantic mappings from unseen data parser predictions hidden understanding model and end-user paraphrases. A baseline version of Gsg has been implemented and preliminary experiments show promising results. 1 Introduction The mapping between words and semantics be it in the form of a semantic grammar 1 or of a set of rules that transform syntax trees onto say a frame-slot structure is one of the major bottlenecks in the development of natural language understanding NLU systems. A parser will work for any domain but the semantic mapping is domain-dependent. Even after the domain model has been established the daunting task of trying to come up with all the possible surface forms by which each concept can 1 .