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<Paper uid="W05-1522">
  <Title>Vancouver, October 2005. c(c)2005 Association for Computational Linguistics From Metagrammars to Factorized TAG/TIG Parsers</Title>
  <Section position="3" start_page="0" end_page="0" type="intro">
    <SectionTitle>
1 Introduction
</SectionTitle>
    <Paragraph position="0"> Large coverage Tree Adjoining Grammars (TAGs) tend to be very large, with several thousands of tree schemata, i.e., trees with at least one anchor node. Such large grammars are difficult to develop and maintain. Of course, their sizes have also a strong impact on parsing efficiency. The size of such TAGs mostly arises from redundancies, due to the extended domain of locality provided by trees.</Paragraph>
    <Paragraph position="1"> Recently, Meta-Grammars (Candito, 1999) have been introduced to factorize linguistic information through a multiple inheritance hierarchy of small classes, each of them grouping elementary constraints on nodes. A MG compiler exploits these bits of information to generate a set of trees. While MGs help reducing redundancies at a descriptive level, the resulting grammars remain very large.</Paragraph>
    <Paragraph position="2"> We propose to exploit the fact that MGs are already factorized to get compact grammars through the use of factorized trees, as provided by system DYALOG (Thomasset and Villemonte de la Clergerie, 2005).</Paragraph>
    <Paragraph position="3"> This proposal has been validated by quickly developing and testing a large coverage French MG.</Paragraph>
  </Section>
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