Inferable Centers, Centering Transitions, and the Notion of Coherence

A centering analysis of the corpus of Japanese e-mail that is examined in this article relies heavily on the inclusion of inferable centers. However, utilizing this type of center results in a high level of indeterminacy in labeling transitions and thus in characterizing the coherence of the corpus. The difficulty lies in the requirement of identity of discourse entities in the definitions of transition states. Lexical cohesion is proposed as a well-defined notion to replace the intuitions captured by the use of inferable centers. Two new transitions, based on lexical relatedness instead of identity, supplement the standard definitions and more adequately characterize coherence in this corpus. Implications and extensions of the proposal are discussed.