Term Encoding of Typed Feature Structures

Abstract

This paper presents an approach to Prolog-style term encoding of typed feature structures. The type feature structures to be encoded are constrained by appropriateness conditions as in Carpenter's ALE system. But unlike ALE, we impose a further independently motivated closed-world assumption. This assumption allows us to apply term encoding in cases that were problematic for previous approaches. In particular, previous approaches have ruled out multiple inheritance and further specification of feature-value declarations on subtypes. In the present approach, these spececial cases can be handled as well, though with some increase in complexity. For grammars without multiple inheritance and specification of feature values, the encoding presented here reduces to that of previous approaches.