Semantic Interpretation Using KL-ONE

Semantic Interpretation Using KL-ONE 1 Norman K. Sondheimer USC/Information Sciences Institute Marina del Rey, California 90292 USA Ralph M. Weischedel Dept. of Computer & Information Sciences University of Delaware Newark, Delaware 19716 USA Robert J. Bobrow Bolt Beranek and Newman, Inc. Cambridge, Massachusetts 02238 USA Abstract This paper presents extensions to the work of Bobrow and Webber [Bobrow&Webber 80a, Bobrow&Webber 80b] on semantic interpretation using KL-ONE to represent knowledge. The approach is based on an extended case frame formalism applicable to all types of phrases, not just clauses. The frames are used to recognize semantically acceptable phrases, identify their structure, and, relate them to their meaning representation through translation rules. Approaches are presented for generating KL-ONE structures as the meaning of a sentence, for capturing semantic generalizations through abstract case frames, and for handling pronouns and relative clauses. 1. Introduction Semantic interpretation is the process of relating the syntactic analysis of an utterance ",o its meaning representatioh. Syntactic analyses associate immediate constituents with their syntactic function in a matrix constituent, e.g., the sentence "Send him the message that arrived yesterday.", has a syntactic analysis in RUS [Bobrow 78] as shown in Figure 1.2 The elements of the meaning representation are the objects, events, and states of affairs perceived by the speaker. The relationships between these entities will be called semantic functions. The basis for our semantic processing scheme is a familiar one based on that of case frames used to describe clausa structure [Bruce 75]. Our case frames are used for all phrase types: clauses, noun phrases, prepositional phrases, etc. We choose to represent both the syntactic and semantic analyses in the knowledge representation language KL-ONE [Brachman&Schmolze 82, Schmolze&Lipkis 83, Moser 83]. The essential properties for the meaning representations constructed are that each concept represents a semantic constituent and each of its roles identifies the semantic function of one of its immediate constituents. Figure 23 gives an analysis of the example sentence above. We have picked a constituent structure and names for semantic functions fitting the computer mail application of .the the Consul project at USC/Information Sciences Institute [Kaczmarek 83]. The exact details of the analysis are not critical; the essential point is that 1This material is based upon work supported in part by the Defense Advanced Research Projects Agency under Contract Numbers MDA 903-81-C-0335, ARPA Order No. 2223, and N00014-77-C-0378, ARPA Order No. 3414. Views and conclusions contained in this paper are the authors' and should not be interpreted as representing the official policies of DARPA, the U.S, Government, or any person or agency connected with them. 2We use this sentence to illustrate many of the points in this paper. Assume that "yesterday" modifies "arrived". 3All of the KL-ONE diagrams in this paper are simplified for expository purposes, semantic interpretation relates a' phrase's analysis based on syntactic criteria to one based on semantic criteria. Clause Head: Send Indire~-I Object: Noun Phrase Head: Him Direct Object Noun Phrase Head: Message Article: The Relative: Clause Head: Arrive Subject: That Time: Yesterday …

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