tailieunhanh - Báo cáo khoa học: "A HYBRID APPROACH TO REPRESENTATION IN THE JANUS NATURAL LANGUAGE PROCESSOR"

In BBN's natural language understanding and generation system (Janus), we have used a hybrid approach to representation, employing an intensional logic for the representation of the semantics of utterances and a taxonomic language with formal semantics for specification of descriptive constants and axioms relating them. Remarkably, of 7,000 vocabulary items in our natural language applications could be adequately axiomatlzed in the taxonomic language. | A HYBRID APPROACH TO REPRESENTATION IN THE JANUS NATURAL LANGUAGE PROCESSOR Ralph M. Weischedel BBN Systems and Technologies Corporation 10 Moulton St Cambridge MA 02138 Abstract In BBN s natural language understanding and generation system Janus we have used a hybrid approach to representation employing an intensional logic for the representation of the semantics of utterances and a taxonomic language with formal semantics for specification of descriptive constants and axioms relating them. Remarkably of 7 000 vocabulary items in our natural language applications could be adequately axiomatized in the taxonomic language. 1. Introduction Hybrid representation systems have been explored before 9 24 31 but until now only one has been used in an extensive natural language processing system. KL-TWO 31 based on a propositional logic was at the core of the mapping from formulae to lexical items in the Penman generation system 28 . In this paper we report some of the design decisions made in creating a hybrid of an intensional logic with a taxonomic language for use in Janus BBN s natural language system consisting of the IRUS-II understanding components 5 and the Spokesman generation components. To our knowledge this is the first hybrid approach using an intensional logic and the first time a hybrid representation system has been used for understanding. In Janus the meaning of an utterance is represented as an expression in WML World Model Language 15 which is an intensional logic. However a logic merely prescribes the framework of semantics and of ontology. The descriptive constants that is the individual constants functions with no arguments the other function symbols and the predicate symbols are abstractions without any detailed commitment to ontology. We will abbreviate descriptive constants throughout the remainder of this paper as constants. Axioms stating the relationships between the constants are defined in NIKL 8 22 . We wished to explore whether a .