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<Paper uid="J94-1003">
  <Title>One-Level Phonology: Autosegmental Representations and Rules as Finite Automata</Title>
  <Section position="4" start_page="57" end_page="58" type="intro">
    <SectionTitle>
5. Well-Formedness Condition:
</SectionTitle>
    <Paragraph position="0"> All vowels are associated with at least one tone; all tones are associated with at least one vowel.</Paragraph>
    <Paragraph position="1"> Association lines do not cross.</Paragraph>
    <Paragraph position="2"> The reader can ascertain that the above charts are well-formed according to (5). However, (5) is insufficiently restrictive on its own, and a further stipulation is required. , Association Convention: Only the rightmost member of a tier can be associated to more than one member of another tier.</Paragraph>
    <Paragraph position="3">  Steven Bird and T. Mark Ellison One-Level Phonology When (5) and (6) are combined, we achieve the effect of one-to-one left-to-right association, where multiple association (or SPREADING) occurs only at the right-hand end. Observe also that the charts in (4) do not contain adjacent identical tones. For example, there is no HH tone melody. This is expressed by a principle attributable to Leben (1973).</Paragraph>
    <Paragraph position="4"> . Obligatory Contour Principle: At the melodic level of the grammar, any two adjacent \[autosegments\] must be distinct. Thus HHL is not a possible melodic pattern; it automatically simplifies to HL.</Paragraph>
    <Paragraph position="5"> Although nonlinear models like autosegmental phonology represent a major advance on the linear model of SPE in the area of explanatory adequacy, it has sometimes been pointed out (e.g., Bird and Ladd 199l) that the formal explicitness of the SPE model has not been matched by these more recent proposals. Before we can begin to compute with autosegmental representations and rules, they need to be given a formal semantics. Our starting point here is the temporal semantics of Bird and Klein (1990), based on Sagey's (1988) model, which has gained widespread acceptance in autosegmental phonology. Under this temporal semantics, phonological properties are attached to intervals that are related using precedence (an asymmetric, transitive relation) and overlap (a reflexive, symmetric relation).</Paragraph>
    <Paragraph position="6"> Bird (1990) showed how a phonological description language can be modeled by such event structures, where the precedence relation models the linear ordering of tiers and the overlap relation models association lines. In this paper, we shall provide an automaton-based semantics for precedence and overlap, thus arriving at a computational semantics for the autosegmental notation.</Paragraph>
  </Section>
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