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<Paper uid="C88-1009">
  <Title>Feature Graphs and Abstract Data Types: A Unifying Approach</Title>
  <Section position="7" start_page="44" end_page="44" type="concl">
    <SectionTitle>
7. Conclusions
</SectionTitle>
    <Paragraph position="0"> We have presented a mathematical semantics of feature graphs and feature graph unification in terms of ADT specifications. It supports various consistency concepts used for feature graphs. The important notion of partiality (\[Pe 87\]) in the sense that arbitrary new features may be unified into a feature graph is supported since any feature graph specification can be extended by arbitrary features, atoms, and equations; there exists no &amp;quot;largest&amp;quot; feature graph specification (unless of course, one adds an artificial &amp;quot;largest&amp;quot; element, e.g. as the $F$-specification in the STUF formalism as described in \[BPU 88\]).</Paragraph>
    <Paragraph position="1"> Another approach bringing together initial ADT spec, i fications and feature graphs is given ill \[SA 87\]. ~t uses an order-sorted approach:, where the set of atoms and features must be fixed in advance, and where every element of a supersort must be in one of its subsorts Compared to the order- sorte%l approach of \[SA 87\] a drawback of the work presented here is the asymetric treatment of the tool; of a feature graph (giving rise to the &amp;quot;se,i&amp;quot; sort) and the other nodes (being mapped t;o thE; &amp;quot;universe&amp;quot; sort ) . We are currently extending out work in order to overcome this disadvantage (\[BP 88\]). Other a:C/eas of future work are the treatment of disjunctJ ons and of functional uncertainty (\[KR 86\], \[Jo 86\]).</Paragraph>
  </Section>
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