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<Paper uid="P85-1022">
  <Title>A Computational Semantics for Natural Language</Title>
  <Section position="1" start_page="0" end_page="172" type="abstr">
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Abstract
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    <Paragraph position="0"> In the new Head-driven Phrase Structure Grammar (HPSG) language processing system that is currently under development at Hewlett-Packard Laboratories, the Montagovian semantics of the earlier GPSG system (see \[Gawron et al. 19821) is replaced by a radically different approach with a number of distinct advantages. In place of the lambda calculus and standard first-order logic, our medium of conceptual representation is a new logical forrealism called NFLT (Neo-Fregean Language of Thought); compositional semantics is effected, not by schematic lambda expressions, but by LISP procedures that operate on NFLT expressions to produce new expressions. NFLT has a number of features that make it well-suited {'or natural language translations, including predicates of variable arity in which explicitly marked situational roles supercede order-coded argument positions, sortally restricted quantification, a compositional (but nonextensional) semantics that handles causal contexts, and a princip\[ed conceptual raising mechanism that we expect to lead to a computationally tractable account of propositional attitudes. The use of semantically compositional LiSP procedures in place of lambda-schemas allows us to produce fully reduced translations on the fly, with no need for post-processing. This approach should simplify the task of using semantic information (such as sortal incompatibilities) to eliminate bad parse paths.</Paragraph>
    <Paragraph position="1"> I. Introduction Someone who knows a natural language is able to use utterances of certain types to give and receive information about the world, flow can we explain this? We take as our point of departure the assumption that members of a language community share a certain mental system -- a grammar -- that mediates the correspondence between utterance types and other things in the world, such as individu~ds, relations, and states of ~ffairs, to a large degree, this system i~ the language. According to the relation theory of meaning (Barwise &amp; Perry !1983!), linguistic meaning is a relation between types of utterance events and other aspects of objective reality. We accept this view of linguistic meaning, but unlike Barwise and Perry we focus on how the meaning relation is mediated by the intersubjective psychological system of grammar.</Paragraph>
    <Paragraph position="2"> \[n our view, a computational semantics \['or a natural language has three essential components:  a. a system of conceptual representation for internal use as a computational medium in processes of information retrieval, inference, planning, etc.</Paragraph>
    <Paragraph position="3"> b. a system of linkages between expressions of the natural language and those of the conceptual representation, and c. a system of linkages between expressions in the conceptual representation and objects, relations, and states of affairs in the external world.</Paragraph>
    <Paragraph position="4"> \[n this paper, we shall concentrate almost exclusively on the first two components. We shall sketch our ontological commitments, describe our internal representation language, explain how our grammar (and our computer implementation) makes the connection between English and the internal representations, and finally indicate the present status and future directions of our research.</Paragraph>
    <Paragraph position="5"> Our internal representation language. NFLT. is due to Creary 119831. The grammatical theory in which the present research is couched is the theory of head grammar (HG) set forth in \[Pollard 1984\] and \[Pollard forthcoming i and implemented as the front end of the HPSG (Head-driven Phrase Structure Grammar) system, an English \[auguage database query system under development at Hewlett-Packard Laboratories. The non-semantic aspects of the implementation are described in IFlickinger, Pollard, &amp; Wasow t9851 and \[Proudian &amp; Pollard 1.9851.</Paragraph>
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