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<Paper uid="E95-1013">
  <Title>Literal Movement Grammars</Title>
  <Section position="6" start_page="95" end_page="96" type="concl">
    <SectionTitle>
5 Conclusions
</SectionTitle>
    <Paragraph position="0"> We have presented the LMG formalism, examples of its application, and a complexity result for a constrained subclass of the formalism. Example 2.9 shows that an LMG can give an elegant account of movement phenomena. The complexity result 3.5 is primarily intended to give an indication of how the recognition problem for LMG relates to that for arbitrary context free grammars. It should be noted that the result in this paper only applies to non-combinatorial LMGs, excluding for instance the grammar of example 2.9 as presented here.</Paragraph>
    <Paragraph position="1"> There are other formalisms (HG and XG) which provide sensible accounts of the three movement phenomena sketched in section 1.3, but altogether do not seem to be able to model all phenomena at once. In (Groenink, 1995b) we give a more detailed analysis of what is and is not possible in these formalisms.</Paragraph>
    <Section position="1" start_page="95" end_page="96" type="sub_section">
      <SectionTitle>
Future Work
</SectionTitle>
      <Paragraph position="0"> 1. The present proof of polynomial complexity does not cover a very large class of literal movement grammars. It is to be expected that larger, Turing complete, classes will be formally intractable but behave reasonably in practice. It is worthwile to look at possible practical implementations for larger classes of LMGs, and investigate the (theoretical and practical) performance of these systems on various representative grammars.</Paragraph>
      <Paragraph position="1">  seems to restrict grammars to treatment of leftward extraposition. In reality, a smaller class of rightward movement phenomena will also need to be treated. It is shown in (Groenink, 1995b) that these can easily be circumvented in left-binding LMG, by introducing artificial, &amp;quot;parasitic&amp;quot; extraposition.</Paragraph>
    </Section>
  </Section>
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