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This paper describes the structure and e v a l u a t i o n of the s y n t a c t i c o - s e m a n t i c lexicon (SSL) of the German Natural Language Understanding System VIE-LANG [3]. VIE-LANG uses an SI-Net [2] as internal r e p r e s e n t a t i o n . The SSL c o n t a i n s the rules according to which the mapping between net-structures and surface s t r u c t u r. | RELATING SYNTAX AND SEMANTICS THE SYNTACTICO-SEMANTIC LEXICON OF THE SYSTEM VIE-LANG Ingeborg steinacker Ernst Buchberger Department of Medical Cybernetics University of Vienna Austria ABSTRACT This paper describes the structure and evaluation of the syntactico-semantic lexicon SSL of the German Natural Language Understanding System VIE-LANG 3 . VIE-LANG uses an Si-Net 2 as internal representation. The SSL contains the rules according to which the mapping between net-structures and surface structures of a sentence is carried out. This information Is structured in a way that it can be evaluated from two sides. The parser interprets it as production-rules that control the analysis. Syntactic and semantic features of the input sentence are evaluated and individuals are created in the semantic net. The generator uses the same rules to express selected net-structures in adequate natural language expressions. It is shown how both processes can make effective use of the SSL. The different possibilities for evaluating the SSL are explained and illustrated by examples. I OVERVIEW OF THE SYSTEM VIE-LANG A. Representation In the system VIE-LANG real world knowledge is represented within a semantic net SN which is realized in the formalism of an Si-Net 2 . The net is organized in two layers. The generic layer contains the static knowledge of the system. At the generic level real world knowledge is represented in the form of concepts and roles. A concept is defined by its attributes which consist of two parts role and value restriction. The value restriction is a concept which defines the range of possible fillers for the attribute the role defines the relation of the filler to the concept being defined. Generic concepts are organized in a hierarchy of super- and subconcepts in which a subconcept inherits all attributes of its superconcepts. The second layer of the net contains the dynamic knowledge which consists of individualized concepts. The parser creates individuals of .
