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<Paper uid="J01-4007">
  <Title>A Reformulation of Rule 2 of Centering Theory</Title>
  <Section position="3" start_page="585" end_page="585" type="concl">
    <SectionTitle>
4. Conclusion
</SectionTitle>
    <Paragraph position="0"> Comparison of the standard preference ordering for centering transitions and Strube and Hahn's (1999) variant has established the following points: 1. The strict ordering of canonical transitions assumed by GJW and others has not (so far) been confirmed by corpus evidence and does not naturally fit into generation architectures. There is no mechanism to predict the Retain-Shift sequence to introduce a new discourse topic.</Paragraph>
    <Paragraph position="1"> 2. By reducing Rule 2 to a requirement for cheap transition pairs, Strube and Hahn weaken the predictive power of the theory while complicating the apparatus with two additional transitions and a 36-position table of cheap versus expensive pairs.</Paragraph>
    <Paragraph position="2"> I have argued that in fact we can dispense with not only Strube and Hahn's two new transition types but the four old ones as well, retaining them only for descriptive convenience. The various different transitions can be seen to emerge in a partial, context-dependent ordering as a result of the interaction of cohesion, salience, and cheapness. Following established practice in empirical work such as that discussed in Section 2.1, centering coherence is applied to inter- as well as intrasegmental transitions. The modified proposal is still weaker than GJW's original formulation as a wider variety of texts is tolerated. This underscores the fact that referential continuity as specified by CT may play an essential part in computing the overall coherence of utterance transitions but it is only one of the determinants of discourse structure.</Paragraph>
  </Section>
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