<?xml version="1.0" standalone="yes"?>
<Paper uid="C90-2018">
  <Title>Feature Logic with Disjunctive Unification</Title>
  <Section position="7" start_page="0" end_page="0" type="concl">
    <SectionTitle>
5 Conclusion
</SectionTitle>
    <Paragraph position="0"> To summarize, we have presented a new unification method for tile full la.nguage of feature logic including variables, sorts and negation which avoids expansion to disjunctiw~ normal form, if possible. The basic principle is to minimize unnecessary interaction of dilt'erent disjunctions by keeph~g thenl local to those attributes which they specify different values for through the introduction of disjunction names. With this treatment we avoid expoimntial explosion in many practical cases. A precursor of this algorithm \[DSrre/Eisele 89\] has been implenlenled and is successfully used in a grammar development environment. Besides the obvious advantage of increased etliciency, our compact representation of disjunctive information also facilitates the comparison of ahernativc solulions with common parts, which has been proved to be a very valuable property in our application. Our algorithm is specified in a completely formalised way as a rewrite system for which a model-.theoretic semantics is given. It may seem that there are a lot of rules, but this can be explained by the following facts: we include a complete reduction from feature terms (like in t(asper/I/ounds logic) to feature descriptions (as used in Lt.&amp;quot;G); we handle all different types of constraints, inchlding sorts ~md negation in one framework; and our rules only involve few primitive operations for which sinrple and fast implementations exist.</Paragraph>
  </Section>
class="xml-element"></Paper>