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<Paper uid="C02-1153">
  <Title>Generating the XTAG English grammar using metarules</Title>
  <Section position="8" start_page="19" end_page="19" type="concl">
    <SectionTitle>
6 Conclusions
</SectionTitle>
    <Paragraph position="0"> The ideas of compact representation of the lexicon are certainly not new, with well known concrete proposals for diverse frameworks (Bresnan, 1982; Gazdar et al., 1985; Pollard and Sag, 1997). For LTAGs, in particular, there has been quite a few proposals, as we have already mentioned (Vijay-Shanker and Schabes, 1992; Becker, 1993; Candito, 1996; Evans et al., 1995; Xia, 2001), and even large-scale grammars built with them, e.g., the French grammar in (Abeille and Candito, 2000) and an English one in (Xia, 2001).</Paragraph>
    <Paragraph position="1"> The work we described in this paper evaluates a particular approach to grammar generation from compact representation. On the one hand, it tests the hypothesis that Becker's tree-transformation rules, the 'metarules', fit well the LTAG formalism and can be effectively and efficiently used to build large-scale such grammars. On the other hand, the facility with which a natural partial ordering of such rules is obtained (here simplified as a total order for practical reasons), dismisses the debate concerning freegeneration, unboundedness, and also weakens the arguments concerning the non-directionality of the metarules, suggesting that they might be more of an academic nature.</Paragraph>
    <Paragraph position="2"> A major strength of the approach is to have set a target grammar with which to compare. A detailed qualitative evaluation of the mismatches between the existing and generated grammars was obtained that allows us to access not only the weaknesses of the generation process but also the problems of the original grammar development: e.g., the inconsistency in the treatment of the interface between the lexicon and the tree templates.</Paragraph>
    <Paragraph position="3"> Future work in the XTAG group includes the construction of a graph based interface for metarules that allows the application of metarules according 10Of course, this may not reflect Becker's view.</Paragraph>
    <Paragraph position="4"> to a partial order, as well as distinct treatment for different families.11 We are also interested in aspects of the use of metarules to enhance extracted grammars (Kinyon and Prolo, 2002).</Paragraph>
  </Section>
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