Grosz, Joshi, and Weinstein (1995): Centering #

This file formalizes the applications of centering in [GJW95], "Centering: a framework for modeling the local coherence of discourse", over the library's centering substrate: the forward-looking centers of an utterance ranked by grammatical role, its backward-looking center, the transitions of section 3, and the two rules of section 6. The paper's discourses are rows of Data.Examples.GroszJoshiWeinstein1995; the study analyzes them at the paper's own annotations and proves its claims about them. Section 2's contrast between (1) and (2) comes out as continuations against retentions and a Rule 1 violation (coherence_contrast); section 5 argues a single backward-looking center ranked by grammatical role from the hamster variants (7) to (10), which Rule 1 separates into the acceptable and the degraded (rule1_separates_variants), and from the subject preference of (11) and (12) and the toy contrast of (13) and (14); section 7 applies the rules to the violation in (15) and its repair by the shift in (16), the full noun phrase center of (17), and the transitions annotated on (20); and section 9 compares centering with [Sid79] on Sidner's example (34), where the centering account makes Jeff the center that the pronoun of (34c) continues (d34_jeff_cb). The section says that Sidner's actor focus, Carl after (34b), makes Carl the leading candidate for that pronoun; Sidner's rule for a pronoun in agent position gives precedence to a discourse focus established before the actor focus, and on it the pronoun co-specifies Jeff, as in her own analysis of the discourse (d34_sidner_foci, d34_sidner_cospecify).

Implementation notes #

Entities are an inductive for the paper's discourses and Sidner1979.Entity for Sidner's, whose discourse D9 the paper's (34) abbreviates; a realization is by name or by pronoun, and grammatical roles are subject, object, and other, ranked in that order, with embedded subjects counting as other. Under the definitions the backward-looking center of (2) stays John throughout, so the paper's informal flipping of aboutness surfaces as two retentions, a violation of Rule 1 at (2b), and a pronoun for an entity outside the forward-looking centers at (2d). Rule 2 is read pointwise over the transition sequences by the order on Transition; its restriction to pairs of utterances is [BFP87]'s, as the paper's footnote notes, and its qualification of the (15) to (16) contrast by [GGG93] is recorded on the rows.

References #

TODO #

The center of (19), realized but not directly realized, the value-free and value-loaded interpretations of (25) to (31), and the referential uses of (32) and (33) in section 8 need a realization relation richer than the substrate's list of directly realized entities.

Grosz, Joshi, and Weinstein (1995): Centering #

Implementation notes #

References #

TODO #

The coherence contrast, section 2 #

Factors governing centering, section 5 #

Applications of the rules, section 7 #

Comparison with Sidner, section 9 #