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<Paper uid="C86-1046">
  <Title>DEPENDENCY UNIFICATION GRAMMAR</Title>
  <Section position="3" start_page="0" end_page="0" type="intro">
    <SectionTitle>
1. Introduction
</SectionTitle>
    <Paragraph position="0"> The recent development of grammar theory exhibits convergencies among various approaches, such as Government-Binding Theory, Generalized Phrase Structure Grammar, Definite Clause Grammar, Lexical Functional Grammar, Functional Unification G~ammar, and others.</Paragraph>
    <Paragraph position="1"> To varying degrees these theories share the following principles: (i) They take into account dependency relations, using notions such as &amp;quot;head&amp;quot; or &amp;quot;governor&amp;quot;. Phenomena such as long distance dependencies are viewed as touC/:hstones for the formalisms.</Paragraph>
    <Paragraph position="2"> (ii) They pay attention to functional aspects.</Paragraph>
    <Paragraph position="3"> The representation of syntactic roles is seen to be a task.</Paragraph>
    <Paragraph position="4"> (iii) They agree that syntax must be lexically restricted and thus place a large portion of the grammatical information in the lexicon.</Paragraph>
    <Paragraph position="5"> (iv) They base their algorithms on the principle of unification, i.e. complex categories are brought into agreement in the syntactic context.</Paragraph>
    <Paragraph position="6"> These common features make it possible to compare the solutions of the different formalisms as well as their problems.</Paragraph>
    <Paragraph position="7"> The main difficulty for the computer application of unification grammars lies in their complexity.</Paragraph>
    <Paragraph position="8"> LFG, for example, bases its syntactic c-structures on the phrase structure principle, while the functional f-structures represent dependency relationships between functors and a~guments. This causes problems for the parser which needs information on both structures while it is creating them. The development of GPSG seems to be marked by the effort to introduce more and more types of rules so as to adequately constrain the formalism. As a result, the control of analysis is distributed over many resources and is, therefore, increasingly difficult. Since a large number of constraints are of a lexical nature, the lexicon becomes more and more unwieldy in all of the formalisms.</Paragraph>
    <Paragraph position="9"> Common advantages and common problems of unification grammars suggest examining strategies from still other frameworks. This is to be done here with respect to dependency grammar. DUG rearranges the available means of description. As a result, the benefits of the common principles are fully felt whereas the difficulties mentioned are largely avoided.</Paragraph>
  </Section>
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