A Property-Sharing Constraint in Centering

1 A constraint is proposed in the Centering approach to pronoun resolution in discourse. This "property-sharing" constraint requires that two pronominal expressions that retain the same Cb across adjacent utterances share a certain common grammatical property. This property is expressed along the dimension of the grammatical function SUBJECT for both Japanese and English discourses, where different pronominal forms are primarily used to realize the Cb. It is the zero pronominal in Japanese, and the (unstressed) overt pronoun in English. The resulting constraint complements the original Centering, accounting for its apparent violations and providing a solution to the interpretation of multi-pronominal utterances. It also provides an alternative account of anaphora interpretation that appears to be due to structural parallelism. This reconciliation of centering/focusing and parallelism is a major advantage. I will then add another dimension called the "speaker identification" to the constraint to handle a group of special eases in Japanese discourse. It indicates a close association between centering and the speaker's viewpoint, and sheds light on what underlies the effect of perception reports on pronoun resolution in general. These results, by drawing on facts in two very different languages, demonstrate the cross-linguistic applicability of the centering framework. using this notion. 2 Centers are semantic objects--(sets of) individuals, objects, states, actions, or events--represented in complex ways so that a strict coreferenee need not hold between anaphorically related terms? A center mentioned in the current utterance may be mentioned again in the next utterance (by the same or a different speaker). In this sense, a center is "forward-looking" (CD. Crucially, one of the centers may be identified as "backward-looking" (Cb). Cb is the entity an utterance most centrally concerns. Its main role is to connect the current utterance to the preceding one(s). 4 The term the Center is also used for the Cb. Thus an utterance may be associated with any number of Cfs, one of which may be the Cb. These Cfs are given a default expected Cb order, that is, "how much each center is expected to be the next Cb". I regard Cb to be optional for an utterance. 5 It comes into exsistence by way of a Cb.establishment process, that is, the process in which a previous non-Cb becomes the new Cb in discourse. Sidner's (1981, 1983) immediate focus and potential foci in local focusing correspond to Cb and Cfs, respectively. The difference is that Sidner uses two immediate foci (Discourse Focus and Actor Focus) while centering uses only one (Cb) (see Grosz et. al. 1983 for discussion). Various factors --syntactic, semantic, and pragmatic-are combined for the identification of the Cb. One of them is the use of pronominal expressions, as expressed in the