Documentation

Linglib.Theories.Discourse.Centering.Instances.InformationStatus

Centering — Information-Status Cf Ranking #

@cite{strube-hahn-1999} @cite{poesio-stevenson-eugenio-hitzeman-2004} @cite{prince-1981} @cite{gundel-hedberg-zacharski-1993}

@cite{strube-hahn-1999} (their §4.2) propose ranking forward-looking centers by information status (IS) — a non-grammatical-function ranker originally argued for free-word-order languages, in particular German. Their ranking projects @cite{prince-1981}'s familiarity scale onto three tiers:

HEARER-OLD ≺ MEDIATED ≺ HEARER-NEW

with linear-order tiebreak within each tier. The relation ≺ is "more salient", so HEARER-OLD entities receive the highest Centering rank; this file inverts the symbol and ranks HEARER-OLD = 2 / MEDIATED = 1 / HEARER-NEW = 0.

@cite{poesio-stevenson-eugenio-hitzeman-2004} (henceforth PSDH) re-evaluate Strube-Hahn's ranking on English corpus data (the GNOME museum + pharmaceutical subcorpora; PSDH §3.2). Internally HEARER-OLD subsumes Prince's evoked + unused entities (e.g. Margaret Thatcher in a politically-knowledgeable context — presumed shared knowledge); MEDIATED covers Prince's inferable, containing- inferable, and anchored-brand-new (PSDH §2.4.3 fn 10); HEARER-NEW covers brand-new entities.

Empirical headline (PSDH §5.1.1). With STRUBE-HAHN ranking, both the IS and IF instantiations verify all three claims (Strong C1, Rule 1 GJW95, Rule 2 BFP) at the .01 level. Switching to GFTHERELIN (grammatical function + linear-order tiebreak), the same IS instantiation verifies Rule 2 only at the .05 level (PSDH §4.4.1 end). The .01-vs-.05 elevation is what STRUBE-HAHN ranking buys — not exclusivity over IF.

Substrate source for IS. The ofGivenness projection below maps @cite{gundel-hedberg-zacharski-1993}'s 6-tier GivennessStatus (in Features/Givenness.lean) onto Strube-Hahn's 3-tier IS — the substantive linguistic bridge the two literatures imply. GHZ's uniquelyIdentifiable/referential populate the MEDIATED tier (Prince's inferable / containing-inferable / anchored-brand-new), witnessed by mediated_reachable below.

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inductive Discourse.Centering.StrubeHahnInfoStatus :
Type

@cite{strube-hahn-1999}'s information-status taxonomy as a Centering-instance-private enum. The 3-tier shape (HEARER-OLD / MEDIATED / HEARER-NEW) is preserved as the Strube-Hahn-native surface; the substrate source is GHZ-6 (see ofGivenness below).

Strube-Hahn's HEARER-OLD covers @cite{prince-1981}'s discourse-old

  • unused/evoked entities (e.g. Margaret Thatcher in a UK political context — presumed shared knowledge). MEDIATED covers Prince's inferable, containing-inferable, and anchored-brand-new. HEARER-NEW covers brand-new entities. Per @cite{poesio-stevenson-eugenio-hitzeman-2004} §2.4.3 (their footnote 10 spells out the Prince-correspondence).
  • hearerOld : StrubeHahnInfoStatus

    Hearer-old: discourse-old or unused/evoked. Highest salience.

  • mediated : StrubeHahnInfoStatus

    Mediated: inferable, containing-inferable, or anchored-brand-new (@cite{prince-1981}'s middle category).

  • hearerNew : StrubeHahnInfoStatus

    Hearer-new: brand-new entity. Lowest salience.

Instances For
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    @[implicit_reducible]
    instance Discourse.Centering.instDecidableEqStrubeHahnInfoStatus :
    DecidableEq StrubeHahnInfoStatus
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    @[implicit_reducible]
    instance Discourse.Centering.instReprStrubeHahnInfoStatus :
    Repr StrubeHahnInfoStatus
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    def Discourse.Centering.instReprStrubeHahnInfoStatus.repr :
    StrubeHahnInfoStatus → ℕ → Std.Format
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    Instances For
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      @[implicit_reducible]
      instance Discourse.Centering.instFintypeStrubeHahnInfoStatus :
      Fintype StrubeHahnInfoStatus
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      def Discourse.Centering.instInhabitedStrubeHahnInfoStatus.default :
      StrubeHahnInfoStatus
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      Instances For
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        @[implicit_reducible]
        instance Discourse.Centering.instInhabitedStrubeHahnInfoStatus :
        Inhabited StrubeHahnInfoStatus
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        def Discourse.Centering.StrubeHahnInfoStatus.rank :
        StrubeHahnInfoStatus → ℕ

        Strube-Hahn IS rank on Nat: HEARER-OLD = 2 (highest Centering rank, matching ≺ = more salient), MEDIATED = 1, HEARER-NEW = 0.

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          @[implicit_reducible]
          instance Discourse.Centering.instCfRankerStrubeHahnInfoStatus :
          CfRanker StrubeHahnInfoStatus

          The Strube-Hahn Cf-ranker instance — sibling of GrammaticalRole, enabling the parametric Centering story PSDH §4.4 evaluate.

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          @[implicit_reducible]
          instance Discourse.Centering.instLinearOrderStrubeHahnInfoStatus :
          LinearOrder StrubeHahnInfoStatus

          Total order via the rank pullback, mirroring the LinearOrder GrammaticalRole instance in the sibling file.

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          def Discourse.Centering.StrubeHahnInfoStatus.ofGivenness :
          Features.GivennessStatus → StrubeHahnInfoStatus

          Project @cite{gundel-hedberg-zacharski-1993}'s 6-tier Features.GivennessStatus onto Strube-Hahn's 3-tier IS, following the GHZ→Prince→Strube-Hahn chain documented in @cite{poesio-stevenson-eugenio-hitzeman-2004} §2.4.3 fn 10:

          • inFocus, activated, familiar → hearerOld (Prince's Evoked + Unused: currently activated, in working memory, or in long-term memory). Strube-Hahn's HEARER-OLD includes Prince's Unused tier — entities like Margaret Thatcher that are part of shared knowledge but not currently activated.
          • uniquelyIdentifiable, referential → mediated (Prince's Inferable + Containing-Inferable + Anchored Brand-new — entities requiring inference or anchoring to be identified).
          • typeIdentifiable → hearerNew (Prince's bare Brand-new).

          The 3-2-1 split is the linguistically-defensible cut implied by Strube-Hahn's own definition. The previous 2-2-2 implementation here mistakenly pushed GHZ's familiar into MEDIATED. The MEDIATED tier has a substrate source (the prior projection from DiscourseStatus had no source for it, leaving MEDIATED unreachable).

          Equations
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            MEDIATED-tier dissolution: substrate-anchor examples #

            The headline of the post-Krifka substrate refactor: GHZ-6's uniquelyIdentifiable and referential finally supply the MEDIATED tier that the old DiscourseStatus-based projection couldn't reach. These rfl examples lock the dissolution as grep-anchored facts.

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            theorem Discourse.Centering.mediated_reachable :
            ∃ (g : Features.GivennessStatus), StrubeHahnInfoStatus.ofGivenness g = StrubeHahnInfoStatus.mediated

            MEDIATED is reachable: there exists a GivennessStatus that projects to it (in fact two — uniquelyIdentifiable and referential). Pre-Krifka the projection was from DiscourseStatus, which had no MEDIATED-suitable input.

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            theorem Discourse.Centering.ofGivenness_monotone (a b : Features.GivennessStatus) :
            a.rank ≥ b.rank → (StrubeHahnInfoStatus.ofGivenness a).rank ≥ (StrubeHahnInfoStatus.ofGivenness b).rank

            The projection respects the salience ordering: more cognitively activated givenness statuses map to higher (or equal) Centering ranks. Sanity check on the substantive linguistic claim that the GHZ-6 hierarchy and Strube-Hahn's IS scale agree about which referents are more salient.