Documentation

Linglib.Theories.Discourse.Centering.Coherence

Centering — Coherence Relation Bridge #

@cite{grosz-joshi-weinstein-1995} @cite{kehler-2002} @cite{poesio-stevenson-eugenio-hitzeman-2004}

A bridge between the discrete CoherenceRelation typology of @cite{kehler-2002} and the discrete Transition typology of @cite{grosz-joshi-weinstein-1995} Rule 2.

The motivation is that both classify how an utterance pair coheres, but along different axes — one in terms of inferential connection (causation, similarity, contiguity) and the other in terms of center continuity. They overlap in their predictions about which configurations are most coherent: elaboration and explanation, which hold the topic constant, pattern with continuation; parallel and occasion, which shift focus while preserving topic, pattern with retaining; and contrast/correction, which substitute the topic, pattern with shifting.

This bridge does not claim the two systems are equivalent — only that they correlate predictably on the canonical cases that motivate Rule 2. @cite{poesio-stevenson-eugenio-hitzeman-2004} formalizes the connection in their PARAMETERIZED-CENTERING-MODEL by tying the choice of ranking-and-instantiation to the discourse genre.

source
def Discourse.Centering.CoherenceRelation.preferredTransition :
Core.Discourse.Coherence.CoherenceRelation → Transition

The transition pattern that the given coherence relation most naturally licenses, on the canonical mapping shared between @cite{kehler-2002} and @cite{grosz-joshi-weinstein-1995}:

  • elaboration / explanation / result — the same entity remains central across the segment boundary, so the prior Cb persists as Cb and typically as Cp ⇒ continuation.

  • occasion / parallel — the topic remains but a new entity may be highlighted in subject position ⇒ retaining.

  • contrast / correction — a new alternative is asserted in place of the prior one, often shifting the Cb itself ⇒ shifting.

These are predictions about preferred patterns, not strict entailments; an actual discourse can violate them and remain interpretable (at a coherence cost).

Equations
Instances For
    source
    theorem Discourse.Centering.causeEffect_continuation :
    CoherenceRelation.preferredTransition Core.Discourse.Coherence.CoherenceRelation.explanation = Transition.continuation ∧ CoherenceRelation.preferredTransition Core.Discourse.Coherence.CoherenceRelation.result = Transition.continuation

    Causal and elaborative relations license the most preferred transition (continuation).

    source
    theorem Discourse.Centering.substitution_shifts :
    CoherenceRelation.preferredTransition Core.Discourse.Coherence.CoherenceRelation.contrast = Transition.shifting ∧ CoherenceRelation.preferredTransition Core.Discourse.Coherence.CoherenceRelation.correction = Transition.shifting

    Resemblance relations of the substitution kind license the least preferred transition (shifting).

    source
    theorem Discourse.Centering.coherence_respects_rule2 :
    (CoherenceRelation.preferredTransition Core.Discourse.Coherence.CoherenceRelation.explanation).rank > (CoherenceRelation.preferredTransition Core.Discourse.Coherence.CoherenceRelation.occasion).rank ∧ (CoherenceRelation.preferredTransition Core.Discourse.Coherence.CoherenceRelation.occasion).rank > (CoherenceRelation.preferredTransition Core.Discourse.Coherence.CoherenceRelation.contrast).rank

    The bridge respects Rule 2's preference order: continuation-licensing relations outrank retaining-licensing relations, which outrank shifting-licensing relations.