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<Paper uid="E95-1011">
  <Title>A Tractable Extension of Linear Indexed Grammars</Title>
  <Section position="8" start_page="79" end_page="81" type="concl">
    <SectionTitle>
6 Conclusions
</SectionTitle>
    <Paragraph position="0"> In considering ways of extending LIG, this paper has introduced the notion of partial linearity and shown how it can be manifested in the form of a constrained unification-based grammar formalism. We have explored examples of the kinds of tree sets and string languages that this system can generate. We have also briefly outlined the sense in which partial linearity gives rise to &amp;quot;context-freeness&amp;quot; in derivations and sketched how this can  be exploited in order to obtain a tractable recognition algorithm.</Paragraph>
  </Section>
class="xml-element"></Paper>