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<Paper uid="C88-2151">
  <Title>Using Constraints in a Constructive Version of GPSG</Title>
  <Section position="1" start_page="0" end_page="0" type="abstr">
    <SectionTitle>
Abstract
</SectionTitle>
    <Paragraph position="0"> Complex categories are caracteristic of unification grammars as for example GPSG \[Shieber86a\]. They are sets of pairs of feature.s and values. The unification, which can be applied to two or more categories, is the essential operation.</Paragraph>
    <Paragraph position="1"> The papers of \[Shieber85\], \[Barton85\] and \[Ristad86\] deal with the influence of complex categories on the efficiency of the parsing algorithm. This is one problem from using complex categories, another one arises when using a constructive version of GPSG (see \[Busemann/Hanensehild88\] in this volume). Namely that the application of admissibility conditions, e.g. LP statements and FCRs 1, to a local tree t is prevented because particular feature values of eategories in t are not yet specified, but they will be instantiated later somewhere else in the complete tree. Similar problems are described * in \[Karttunen86\] for D-PATR.</Paragraph>
    <Paragraph position="2"> This work describes the latter problem and will present a solution working with computation, evaluation and propagation of constraints within local trees (depth 1). The constraint evaluation will reject local trees if the constraints of the subtrees of the daughters are violated.</Paragraph>
  </Section>
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