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<Paper uid="C92-1030">
  <Title>An Empirical Study on Rule Granularity and Unification Interleaving Toward an Efficient Unification-Based Parsing System</Title>
  <Section position="6" start_page="0" end_page="0" type="evalu">
    <SectionTitle>
5 Experiment
</SectionTitle>
    <Paragraph position="0"> Tile effectiveness of the strategies proposed in this paper call be judged by observing their behavior in practice. We have tested the time behavior of parslug with respect to rule granularity and interleaving strategy of CFG parsing and unification. 85 sample sentences are used. These are selected from the sample subcorpus of ATR's dialogue corpus whose teu~k dornain is the &amp;quot;secretarial service of an international conference&amp;quot;. The average length of the sample sentences is 11.0 characters, and their maximum and minimum length are 2 and 28 characters, respectively.</Paragraph>
    <Paragraph position="1"> We have developed two 3 al)anese grammars of different granularity with ahnost the same coverage.</Paragraph>
    <Paragraph position="2"> The coarse-grained rules consist of 22 generalized phrase structure rules with detailed ti~.ature description ill their annotations, while the medium-grained rules consist of 164 detailed phra.se structure rules with less detailed feature descriptions. Both grammars use the same lexicon with about 400 lexical cn tries. We haw: ,also implemented two different fca ture descrilrtion evaluation modes in tile active chart parser. 'file early unificalion cwdurdion mode evah&gt; ates tile feature descriptions at each rule application (tile step-by-step strategy). The late uniJica*io, cvalualio~ mode, on the other hand, delays unification until a CUlnl)lete syntactic structure is tk~und lly using the atomic phrase structure rules only (tile pipelin,~ strategy).</Paragraph>
    <Paragraph position="3"> The average parsing tilne is shown ill Table :1 It shows that, on average, tile m(~diun&gt;grained glum Sin o/u. implelnentation, for e|liciency l'e~ualls, w~: gellotal~&amp;quot; all the approl)fiate combinations of sul)cat and sl:tsl~ in ~ul V&amp;IICe, atld kee I) thertl ~.s a disjunctive fe~tttll'e st rttcLiil'O</Paragraph>
    <Section position="1" start_page="0" end_page="0" type="sub_section">
      <SectionTitle>
Medimn-(-;rained Rules
</SectionTitle>
      <Paragraph position="0"> mar rules are 1.7 times more elllcient than the coarse grained rules ill the early unit|cation mode, and that tile late unification mode is 2.0 times more etncient than tile early unilieation mode with the medium~ grained gramniar. Moreover, when tile mediuulgrained grauunar rules and tile late unification mode m'e combined, tile new parser runs 3.5 times fmqter than till', l/revklus olle using the coarse-grained grammar rules and the early unities|ion. 4</Paragraph>
    </Section>
  </Section>
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