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<Paper uid="J88-2002">
  <Title>TENSE, QUANTIFIERS, AND CONTEXTS</Title>
  <Section position="2" start_page="0" end_page="0" type="abstr">
    <SectionTitle>
1 INTRODUCTION
</SectionTitle>
    <Paragraph position="0"> JANUS is a natural language understanding and generation system that allows the user to interface with several knowledge bases maintained by the U.S. Navy.</Paragraph>
    <Paragraph position="1"> The knowledge bases contain, among other things, information about the deployment schedules, locations, and readiness conditions of the ships in the Pacific Fleet.</Paragraph>
    <Paragraph position="2">  I. a. Did the admiral deploy the ship? b. List all ships as of 4-1-86.</Paragraph>
    <Paragraph position="3"> c. Which C3 ships are now C4? d. When will Vincent arrive in Hawaii? e. Who was Frederick's previous commander? f. Every admiral has to deploy a ship today.  As the sample queries in (1) demonstrate, much of this information is highly time-dependent: ships change locations in accordance with their deployment schedules. They can incur equipment failures or undergo personnel changes. Such events, in turn, can affect the ships' readiness ratings, which are expressed by codes such as C3 or C4. Much of the information that the JANUS user is trying to access is time-dependent in that an appropriate answer can be given only if the time of the query and/or the time of the events in question are taken into account. It is, therefore, imperative that at the level of semantic representation of the natural language input an adequate analysis can be provided for those linguistic expressions that carry time information: for example, tenses, temporal adverbials, and temporal adjectives. The rest of this paper is organized as follows: In Section 2, I will sketch the basic ideas of the framework of logical semantics, or more specifically, of Montague Grammar, the framework that I will use for my analysis. Section 2 also gives a brief overview of the conceptual modularity of the JANUS system, which demonstrates how Montague Grammar as a linguistic theory can be applied in natural-language processing research. In sections 3-8, I will address the subject matter of temporal semantics itself. My own analysis of temporal semantics is very much a response to the kinds of analyses that have been provided in classical tense logic. Section 3, therefore, provides a brief overview of analyses of the latter type. In Section 4, I will review some well-known problems that arise when one applies classical tense logics to the semantics of natural language. In Section 5, I will show how a logic with multiple indices that is based on Reichenbach's analysis of English tense can overcome most of the problems that standard tense logic cannot. While this richer logic will solve most of our problems, the issue of tense and noun-phrase (NP) Copyright 1988 by the Association for Computational Linguistics. Permission to copy without fee all or part of this material is granted provided that the copies are not made for direct commercial advantage and the CL reference and this copyright notice are included on the first page. To copy otherwise, or to republish, requires a fee and/or specific permission. 0362-613X/88/01003-14503.00 Computational Linguistics, Volume 14, Number 2, June 1988 3 Erhard W. Hinrichs Tense, Quantifiers, and Contexts quantification does require additional refinements of the analysis. Section 6 will show how giving narrow scope to tense quantifiers enables us to provide adequate scope relations with respect to NP quantifiers. In addition, I will show how a contextual analysis of nouns and noun phrases lets us account for the kind of temporal phenomena that were first discussed in Enc 1981, 1986.</Paragraph>
    <Paragraph position="4"> In Section 7, I argue that the context-dependent feature of the analysis does not add extra complexity to my treatment of time-dependent expressions, but is needed for purposes of discourse understanding in general.</Paragraph>
    <Paragraph position="5"> Finally, I will demonstrate in Section 8 how the narrow scope of tense also leads to a compositional syntax and semantics of tensed sentences in English.</Paragraph>
  </Section>
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