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<Paper uid="C00-1011">
  <Title>Parsing with the Shortest Derivation</Title>
  <Section position="7" start_page="73" end_page="73" type="concl">
    <SectionTitle>
5. Conclusion
</SectionTitle>
    <Paragraph position="0"> Commou wisdom has it that tile bias o1' stochastic grammars ill favor of shorter derivations is harnfful and should be redressed. We have shown that the common wisdom is wrong for stochastic treksubstitution grammars that use elementary trees (11' flexible size. For such grammars, a non-probabilistic metric based on the shortest derivation outperforms a probabilistic metric on tile ATIS and OVIS corpora, while it obtains competitive results on tile Wall Street Journal corpus. We have seen that a non-probabilistic version o1' DOP performed especially well on corpora for which collecting sublree statistics is difficult, while sentences can still be parsed by relatively large chunks. We have also seen that probabilistic DOP obtains very competitive results on the WSJ corpus. Finally, we conjecture thai any stochastic grammar which uses elementary treks rather than context-free rules can be turned into an accurate non-probabilistic version (e.g. Tree-Insertion Grammar and Tree-At\[joining Grammar).</Paragraph>
  </Section>
class="xml-element"></Paper>