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<Paper uid="C88-2128">
  <Title>A Uniform Architecture for Parsing and Generation</Title>
  <Section position="3" start_page="0" end_page="0" type="intro">
    <SectionTitle>
1 Introduction
</SectionTitle>
    <Paragraph position="0"> the use of a single grammar for both parsing and generation is an idea ~ith a certain elegance, the desirability of which several researchers nave noted. Of course, judging the correctness of such a system requires a characterization of the meaning of grammars that is independent of their use by a particular processing, mechanism--that is, the brmalism in which the grammars are expressed must have an abstract ~emantics. As a paradigm example of such a formalism, we might take ~ny of the various logic- or unification-based grammar formalisms.</Paragraph>
    <Paragraph position="1"> As described by Pereira and Warren \[1983\], the parsing of strings ~ccording to the specifications of a grammar with an independent logcal semantics can be thought of as the constructive proving of the ;tring's grammaticality: parsing can he viewed as logical deduction.</Paragraph>
    <Paragraph position="2"> -3ut, given a deductive framework that can represent the semantics ff the formalism abstractly enough to be independent of processing, he generation of strings matching some criteria can equally well be hought of as a deductive process, namely, a process of constructive ~roof of the existence of a string that matches the criteria. The diference rests in which information is given as premises and what the ~oal is to be proved. This observation opens up the following possibility: not only can a single grammar be used by different processes ~ngaged in various &amp;quot;directions&amp;quot; of processing, but one and the same anguage-processing architecture can be employed for processing the grammar in the various modes. In particular, parsing and generatioa :an be viewed as two processes engaged in by a single parameterized ;heorem prover for the logical interpretation of the formalism.</Paragraph>
    <Paragraph position="3"> We will discuss our current implementation of such an architecture, ~hich is parameterized in such a way that it can be used either for ~arsing or generation with respect to grammars written in a particular ~rammar formalism which has a logical semantics, the PATR formalsm. Furthermore, the architecture allows fine tuning to reflect differmt l:':ocessing strategies, including parsing models intended to mimic )s~'cholinguistiC phenomena. This tuning allows the parsing system to )perate within the same realm of efficiency as previous architectures or parsing alone, but with much greater flexibility for engaging in ,ther processing regimes.</Paragraph>
    <Paragraph position="4"> *This research was sponsored by the Nippon Telegraph and Telephone Corpoation under a contract with SRI International.</Paragraph>
  </Section>
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