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<Paper uid="C00-1080">
  <Title>Chart Parsing and Constraint Programming</Title>
  <Section position="5" start_page="556" end_page="556" type="concl">
    <SectionTitle>
4 Conclusion
</SectionTitle>
    <Paragraph position="0"> In the paper, the similarity between parsing-as-deduction and constraint propagation is used to propose a llexible and simple system which is easy to implement and flmrefore offers itself as a tcstbed for different parsing strategies (such as top-down or bottom-up), for wu'ying modes * of processing (such as left-to-right or right-to-left) or for different types of grammars (such as for example minimalist grammars). Compared to the Shieber al)proach, the pure version see,ns to be lacking in efliciency. This can be remedied by providing an automatic compilation into more eflicient specialized parsers.</Paragraph>
    <Paragraph position="1"> While the paper has shown that existing constraint systems are powerful enough to allow chart parsing, more work has to be invested in the realization of such a larger system combining these techniques with constraint solvers lbr existing constraint-based natural language theories m see whether ft,rther benelils can be gotten from using parsing as constraint propagation. Dt, e to the tlexibility of the CHR system, one can now use the constraint propagation approach to drive other constraint solving or constraint resolution techniques (also implemented in CHR) resulting in a homogenous environment which combines both classical constraint solving with a more operational generator.</Paragraph>
    <Paragraph position="2"> Specifically, one can use each created edge to post other constraints, for example about the wdl-formedness of associated typed feature structures. By posting them, they become available for other constraint handling rules.</Paragraph>
    <Paragraph position="3"> In particular, systems directly implementing HPSG seem to suffer fi'om the problem how to drive the constraint resolution process efficiently. Some systems, as for example ALE (Carpenter and Penn, 1998) use a phrase structtH'e backbone to drive tile process. Tile p,oposal here would allow to use 111e ID/LP schemata directly as constraints, but nevertheless as the driving tbz'ce behind lhe other constraint satisfi~ction techniques. However, for the moment this remains speculative.</Paragraph>
  </Section>
class="xml-element"></Paper>