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<Paper uid="P89-1028">
  <Title>TREE UNIFICATION GRAMMAR</Title>
  <Section position="9" start_page="234" end_page="235" type="concl">
    <SectionTitle>
SUMMARY
</SectionTitle>
    <Paragraph position="0"> In TUG, the phonological, syntactic, semantic and antecedent information describing linguistic expressions is contained in signs which are organised into FA structures. These FA structures are binary ores which encode the functor-argurnent dependencies between the signs corresponding to components of a complex expression. Partial specifications of FA structures are associated with individual lexical entries and these FA specifications are combined by a single grammar role. Dependencies between information associated with different linguistic constituents that.</Paragraph>
    <Paragraph position="1"> are traditionally captured by grammar roles are captured explicitly in the TUG lexical entries. TUG can in some sense be viewed as a 'lexicalised' UCG, where 'lexicelised' is.used in the sense discussed in (Schabes, Abeille and Joshi, 1988).</Paragraph>
    <Paragraph position="2"> However, the FA structures described by a TUG analysis of a sentence are difficult to obtain as derivation trees in UCG. As discussed earlier, the UCG grammar roles require the semantic attributes of the root-sign and fonctor-sign of any subtree to be the same. Additional grammar rules would be needed by UCG to allow the diffenmt relationShil~S between semantic infonmation  and to allow the three different relations between the R-antecedent information of a root-sign and functor-sign. The R-antecedent information of a functor-sign can either be the same as that of the mot-sign (non-predicative functors), or it can consist of the semantic index of its argument in addition to the R-antecedent information of the mot-sign (po-.dicative functors), or it can contain only the sanantic index of its argument (generalised predicative functors).</Paragraph>
    <Paragraph position="3"> The R-antecedent information contained in FA specifications is treated on a level equal to the other forms of information; there is no need to invoke special mechanisms for passing this information. Its distribution is governed by the predication command and generalised predicative constraints. The reflexive attribute of the sign contains information that m/ght be needed by a reflexive pronoun. So if a sign for a reflexive pronoun appears in an FA specification, the possible anteee_aen_ ts for the reflexive are easily accessible. During ~ unification, if the sign associated with a reflexive pronoun contains no variables of the appropriate son in its reflexive store, then the use of the pronoun is ungrammatical md tree unification fails. Since an FA specification is associated with each potential antecedent of a reflexive proneen, failure of anaphora resolution can constrain possible analyses; if there is no possible antecedent for a reflexive, there will not be an FA specification.</Paragraph>
  </Section>
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