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<Paper uid="C90-3050">
  <Title>Towards a Unification-Based Phonology</Title>
  <Section position="3" start_page="284" end_page="285" type="concl">
    <SectionTitle>
4 Conclusions
</SectionTitle>
    <Paragraph position="0"> The relationship between phonology and computational linguistics has various aspects. On one level, one might want to argue for a better treatment Of phonological knowledge in language-processing systems (see remarks in Wiese 1986). On another level, it is instructive to observe how phonological theory can be shaped by explicitly computational considerations.</Paragraph>
    <Paragraph position="1"> Rules in non-linear phonology are to a large extent not feature-changing, especially if underspeci- null fication theory is utilized as well. This observation constitutes additional motivation for the line of reasoning in this paper. We hope to have shown, first, that an analysis of FD without the invocation of a feature-changing rule is actually the preferred solution. Secondly, a large number of well-established rules, namely the members of the class of neutralization rules, can be analysed as particular instances of unification.</Paragraph>
    <Paragraph position="2"> However, the concept of generalization (as a formal interpretation of delinking as this concept is standardly used in non-linear phonology) cannot be avoided in an adequate treatment of these cases.</Paragraph>
    <Paragraph position="3"> It is in the very nature of neutralization that some information (here on the voicing of a consonant) is not retained under specific circumstances. In that sense, phonological rule applications cannot constitute a strictly monotonic system, unless we are willing to give up well-motivated linguistic generalizations. Finally, we take side with Hammond (1988) on the question of how association lines are to be interpreted: transitivity is a crucial property of these relations, since the feature structures are highly hierarchical.</Paragraph>
    <Paragraph position="4"> Future work in this area must also answer the question what principles determine and restrict the applicability of generalization. Generalization should not be applicable whenever unification fails. But it seems to be in the nature of phonology that linguistic items can be realized even if they violate some valid wellformedness conditions: Lexical entries in German end up being realized as words despite the fact that they contain an underlying voiced obstruent which violates FD. In numerous other cases, whole segments are deleted because they do not conform to phonotactic patterns or similar constraints. It is in this area that unification must be supplemented with generalization.</Paragraph>
    <Paragraph position="5"> Footnotes i) Theories with only one level of description, especially in the work of Vennemann, provide the major exception to this statement.</Paragraph>
    <Paragraph position="6"> 2) Application of FD to recent Ioan words such as orange in (i) shows first that this rule is totally productive, and, secondly, that it is indeed applicable to all segments marked as \[- sonorant\]. The native stock of German words does not display a phoneme /3/, but in orange this sound is readily devoiced to /f/.</Paragraph>
    <Paragraph position="7"> 3) Details of syllable structure are omitted, because they are irrelevant for present purposes.</Paragraph>
    <Paragraph position="8"> 4) The feature \[voiced\] used here in the description of FD is probably a short-hand notation fc~r a particular configuration of the laryngeal states. In (5) it is expressed as a particular configuration of glottal states.</Paragraph>
    <Paragraph position="9"> 5) This comes in two sub-eases: the spreading of a feature value to several nodes, as in the various harmony and assimilation rules, and the linking of a &amp;quot;floating&amp;quot; feature to a node.</Paragraph>
    <Paragraph position="10"> 6) The markings in (7) hold for all occurrences of /d/and/t/. Here lies the difference to the classical archiphonemie treatment of neutralization (Jakobson 1929, Trubetzkoy 1939), where an archiphoneme /D/ is postulated only in the context of neutralization.</Paragraph>
  </Section>
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