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<Paper uid="P87-1032">
  <Title>INCORPORATING INHERITANCE AND FEATURE STRUCTURES INTO A LOGIC GRAMMAR FORMALISM</Title>
  <Section position="9" start_page="231" end_page="231" type="concl">
    <SectionTitle>
IMPLEMENTATION
</SectionTitle>
    <Paragraph position="0"> We have implemented an IG development environment in Smalltalk on the Tektronix 4406. The IS-A statements are handled by an ordering package which dynamically performs the lattice extension and which allows interactive display of the ordering. Many of the techniques used in standard depth-first Prolog execution have been carried over to IG execution.</Paragraph>
    <Paragraph position="1"> To speed grammar execution, our system precompiles the grammar rules. To speed grammar development, incremental compilation allows individual rules to be compiled when modified. We are currently developing a large grammar using this environment.</Paragraph>
    <Paragraph position="2"> As in Prolog, top-down evaluation is not complete. Earley Deduction (Pereira and Warren, 1980; Porter, 1986), a sound and complete evaluation strategy for Logic programs, frees the writer of DCGs from the worry of infinite left-recursion. Earley Deduction is essentially a generalized form of chart parsing (Kaplan, 1973; Winograd, 1983), applicable to DCGs. We are investigating the application of alternative execution strategies, such as Earley Deduction and Extension Tables (Dietrich and Warren, 1986) to the execution of IGs.</Paragraph>
  </Section>
class="xml-element"></Paper>