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A New Semantic Computation While Parsing: Presupposition and Entailment

IP.com Disclosure Number: IPCOM000128330D
Original Publication Date: 1976-Dec-31
Included in the Prior Art Database: 2005-Sep-15
Document File: 23 page(s) / 69K

Publishing Venue

Software Patent Institute

Related People

Ralph M. Weischedel: AUTHOR [+3]

Abstract

This paper treats the computation of presupposition and entailment while parsing. We also discuss certain phenomena that presupposition and entailment exhibit, and the details of their computation via tree transformations. . In particular, we show how to organize an augnented transition network (ATN) and how to write lexical entries in order to compute presupposition and entailment,

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THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

A New Semantic Computation While Parsing: Presupposition and Entailment*

Ralph M. Weischedel'*

TECHNICAL REPORT #76

*The work was carried out while the author was in the Department of Computer and Information Science, University of Pennsylvania, Philadelphia, PA 19174. It was Dartially supported by NSF Grant SOC 72-0546AO1.

**Department of Information and Computer Science, University of California, Irvine, CA 92717.

ABSTRACT

This paper treats the computation of presupposition and entailment while parsing. We also discuss certain phenomena that presupposition and entailment exhibit, and the details of their computation via tree transformations. . In particular, we show how to organize an augnented transition network (ATN) and how to write lexical entries in order to compute presupposition and entailment,

Presupposition and entailment are a subclass of inferences that seem to be tied to the structure of language. Distinguishing presupposition and entailment from the general class of inferences enables this subclass to be computed while parsing. This subclass of inferences is further distinguished in that they appear to be relatively independent of context.

Introduction

Because natural languages exhibit complex interaction of syntax, semantics, and pragmatics, many computational models of natural languge have included certain semantic computations in a syntactic input component. Winograd (1972) incorporated a search for referents of noun phrases to guide parsing of noun phrases. Davies and Isard (1972) demonstrated the computation of semantic representations of sentences, without overtly computing syntactic structures for sentences. These are just a few among several examples.

This paper discusses the computation of a subclass o f inferences while parsing. We demonstrate the details of writing an augmented transition network (ATN) parser and its lexicon to compute the presuppositions and entailments of a sentence. Tree transformations are used in the computation.

Section 1 defines presupposition and entailment. Section 2 demonstrates several phenomena exhibited by presupposition and eatailment. Sections 2 and 3 show that the computation is more than a simple composition of the pieces of semantic representation stored in registers of the ATN. Sections 3, 4, and 5 detail the computation of presupposition, the computation of entailment, and their computation in compound sentences, respectively. Section 6 suggests a criterion for what semantic information belongs in a lexicon. Section 7 presents our conclusions.

University of California, Irvine Page 1 Dec 31, 1976

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A New Semantic Computation While Parsing: Presupposition and Entailment

Appendix A indicates the syntactic constructions of the system. Appendix B contains some sample terminal sessions.

1. Definitions

Several terms and assumptions should be made clear before proceeding further. We assume that the goa...