Documentation

Linglib.Studies.ScontrasPearl2021

[SP21]: quantifier scope ambiguity in truth-value judgments #

"When pragmatics matters more for truth-value judgments: An investigation of quantifier scope ambiguity", Glossa 6(1): 110. A modeling paper: RSA with lifted scope and QUD variables explains the endorsement patterns of [ML03] and successors, separating pragmatic factors (world and QUD priors) from grammatical processing (scope access).

Two models, each in its own namespace and each with two faces — an exact-ℚ≥0 kernel face at the paper's parameters and a general-α structural face on RSA/PMF.posterior operators:

Main results #

Implementation notes #

Truth conditions are grounded compositionally (every_sem, ScopeDerivation) and in the named numeral meanings of Semantics.Numerals. The kernel faces use PMF.ofScores over ℚ≥0 score chains at α = 1 (§3.2; costs cancel, fn. 8) with L0 taking no world prior (fn. 6); the structural faces are parametric in α (the parametric-prior layer is TODO). Developmental claim (§3.3): children and adults differ only in these parameter values.

TODO #

General-α, parametric-prior versions of the QUD ordering and of the exact-vs-at-least endorsement divergence (their α = 1 instances at the paper's parameters are kernel-proved), together with the parametric prior layer (PMF.binomial world prior, weighted scope/QUD priors) and the general S2 they require; the emergent b_suc-monotonicity of endorsement as a limit statement.

Shared domain: every-not (n = 2) #

How many horses jumped (out of 2).

Instances For
    @[implicit_reducible]
    Equations
    Equations
    • One or more equations did not get rendered due to their size.
    Instances For
      @[implicit_reducible]
      Equations
      • One or more equations did not get rendered due to their size.

      Scope configuration for "every...not".

      Instances For
        @[implicit_reducible]
        Equations
        Equations
        • One or more equations did not get rendered due to their size.
        Instances For
          @[implicit_reducible]
          Equations
          • One or more equations did not get rendered due to their size.

          Shared domain: two-not (n = 4) #

          How many horses jumped (out of 4).

          Instances For
            @[implicit_reducible]
            Equations
            Equations
            • One or more equations did not get rendered due to their size.
            Instances For
              @[implicit_reducible]
              Equations
              • One or more equations did not get rendered due to their size.

              Numeral reading: does "two" mean exactly 2 or at least 2?

              Instances For
                @[implicit_reducible]
                Equations
                Equations
                • One or more equations did not get rendered due to their size.
                Instances For
                  @[implicit_reducible]
                  Equations
                  • One or more equations did not get rendered due to their size.

                  Truth conditions for "two horses didn't jump" with n=4 horses (paper (6)).

                  Parameterized by numeral reading and scope configuration.

                  Surface scope (two > not): "There are two horses that didn't jump"

                  • Exact: exactly 2 didn't jump → exactly 2 jumped → w=2
                  • At-least: at least 2 didn't jump → at most 2 jumped → w ∈ {0,1,2}

                  Inverse scope (not > two): "It's not the case that two horses jumped"

                  • Exact: ¬(exactly 2 jumped) → w ≠ 2 → w ∈ {0,1,3,4}
                  • At-least: ¬(at least 2 jumped) → fewer than 2 jumped → w ∈ {0,1}
                  Equations
                  Instances For

                    Scope-entailment asymmetry ([ML03]) #

                    For universals, surface scope (∀>¬: none jumped) ENTAILS inverse scope (¬>∀: not all jumped). If no horse jumped, then trivially not every horse jumped. This means no truth-value judgment context can diagnose the isomorphism effect for universals: whenever surface is true, inverse is automatically true too.

                    The entailment is strict: inverse does NOT entail surface. At w=1 (one horse jumped), inverse scope is true (not all jumped) but surface scope is false (not none jumped).

                    For exact numerals, surface scope does NOT entail inverse scope. At w=2 (exactly 2 jumped out of 4), surface is true (exactly 2 didn't) but inverse is false (it IS the case that exactly 2 jumped). This independence is what makes numerals diagnostic for the isomorphism effect.

                    Inverse scope also does not entail surface for exact numerals. At w=0 (none jumped), inverse is true (¬(exactly 2 jumped)) but surface is false (not exactly 2 didn't jump, since all 4 didn't).

                    Numeral-semantics grounding #

                    Connects S&P's twoNotTruth truth conditions to linglib's numeral semantics infrastructure (named meanings in Semantics.Numerals).

                    The truth conditions in the data file are grounded in the named meanings:

                    Convergent evidence for exact semantics from [Ken15] (de-Fregean semantics where bare numerals mean =n) and [Mus04] (acquisition data — children reject "two" at w=3).

                    Exact surface: "exactly two didn't jump" (out of 4) ↔ exactly two jumped. Matches bareMeaning 2 applied to the complement count (4 - w).

                    At-least surface: "at least two didn't jump" ↔ at most two jumped. Matches atLeastMeaning 2 applied to the complement count.

                    The negation-scope asymmetry collapses under exact semantics: internal negation ¬(=3) and external negation ≠3 agree at world 4.

                    Lower-bound semantics preserves the negation-scope distinction: internal negation ¬(≥3) and external negation ≠3 diverge at world 4.

                    [Ken15]'s resolution: exact meaning is basic, lower-bound is derived via type-shift. Both meanings are grammatically available.

                    The every-not model (§3) #

                    Utterances: null (silence) or "Every horse didn't jump".

                    Instances For
                      @[implicit_reducible]
                      Equations
                      Equations
                      • One or more equations did not get rendered due to their size.
                      Instances For
                        @[implicit_reducible]
                        Equations
                        • One or more equations did not get rendered due to their size.

                        QUDs partition worlds by the question under discussion (paper (3)). Three QUD partitions for n=2 worlds.

                        Instances For
                          @[implicit_reducible]
                          Equations
                          Equations
                          • One or more equations did not get rendered due to their size.
                          Instances For
                            @[implicit_reducible]
                            Equations
                            • One or more equations did not get rendered due to their size.

                            Flattened latent variable: scope reading × QUD. Flat inductive avoids Prod, keeping proof terms tractable for the kernel checker.

                            Instances For
                              @[implicit_reducible]
                              Equations
                              Equations
                              • One or more equations did not get rendered due to their size.
                              Instances For
                                @[implicit_reducible]
                                Equations
                                • One or more equations did not get rendered due to their size.

                                Truth conditions and compositional grounding #

                                RSA meaning derived from scopeTruth. Null utterance is always true (uninformative baseline).

                                Equations
                                Instances For

                                  2-horse domain for grounding truth conditions in quantifier semantics.

                                  Instances For
                                    @[implicit_reducible]
                                    Equations
                                    @[implicit_reducible]
                                    Equations
                                    • One or more equations did not get rendered due to their size.

                                    Restrictor: all entities are horses (trivial for this model).

                                    Equations
                                    Instances For

                                      Surface scope grounding: scopeTruth.surface derives from compositional ⟦every⟧(horse)(λx.¬jump(x)), not stipulation.

                                      Inverse scope grounding: scopeTruth.inverse derives from negating the compositional ⟦every⟧(horse)(jump).

                                      "Every horse didn't jump" as a ScopeDerivation: a single syntactic form with multiple semantic values indexed by scope configuration.

                                      Equations
                                      • One or more equations did not get rendered due to their size.
                                      Instances For

                                        The ScopeDerivation's meaningAt agrees with scopeTruth for both readings: when scopeTruth is true, the compositional derivation holds, and vice versa.

                                        RSA meaning is grounded in ScopeDerivation: the meaning function used by the RSA config matches the compositional scope derivation.

                                        The every-not scope pair has surface-entails-inverse structure, making universals non-diagnostic for scope preferences: no truth-value judgment context can distinguish isomorphic from non-isomorphic behavior.

                                        The kernel face: exact-ℚ scores at the paper parameters #

                                        Literal listener (fn. 6: no world prior in L0).

                                        Equations
                                        • One or more equations did not get rendered due to their size.
                                        Instances For
                                          def ScontrasPearl2021.EveryNot.qProj {M : Type u_1} [Add M] (q : QUD) (f : JumpOutcomeM) :

                                          QUD projection (paper (3)): sums f over the QUD cell of the world. Polymorphic over the value monoid — instantiated at ℚ≥0 by the kernel face and at ℝ≥0∞ by the structural face.

                                          Equations
                                          Instances For

                                            Speaker (α = 1, §3.2; costs cancel, fn. 8).

                                            Equations
                                            • One or more equations did not get rendered due to their size.
                                            Instances For
                                              def ScontrasPearl2021.EveryNot.l1Score (wp : JumpOutcomeℚ≥0) (sp : ScopeReadingℚ≥0) (qp : QUDℚ≥0) (u : Utt) (w : JumpOutcome) :
                                              ℚ≥0

                                              Joint pragmatic-listener world score: P(w)·Σ_{i,q} P(i)·P(q)·S1.

                                              Equations
                                              Instances For
                                                def ScontrasPearl2021.EveryNot.l1Post (wp : JumpOutcomeℚ≥0) (sp : ScopeReadingℚ≥0) (qp : QUDℚ≥0) (u : Utt) :
                                                JumpOutcomeℚ≥0

                                                Normalized world posterior.

                                                Equations
                                                Instances For

                                                  Uniform scope prior (P(inverse) = 0.5, the default).

                                                  Equations
                                                  Instances For

                                                    Uniform QUD prior.

                                                    Equations
                                                    Instances For
                                                      def ScontrasPearl2021.EveryNot.biasQP (q₀ : QUD) :
                                                      QUDℚ≥0

                                                      Biased QUD prior: the favored QUD gets 0.9, others 0.05 (∝ 18:1:1).

                                                      Equations
                                                      Instances For
                                                        noncomputable def ScontrasPearl2021.EveryNot.l1 (wp : JumpOutcomeℚ≥0) (sp : ScopeReadingℚ≥0) (qp : QUDℚ≥0) (u : Utt) :

                                                        Pragmatic listener over worlds.

                                                        Equations
                                                        Instances For
                                                          noncomputable def ScontrasPearl2021.EveryNot.s2 (wp : JumpOutcomeℚ≥0) (sp : ScopeReadingℚ≥0) (qp : QUDℚ≥0) (w : JumpOutcome) :
                                                          PMF Utt

                                                          Endorsement speaker S₂ (§3.1): the L1 world posterior renormalized per world.

                                                          Equations
                                                          Instances For

                                                            L₁ predictions #

                                                            Baseline L₁ (b_suc = 0.1) ranks the worlds w0 > w1 > w2: both scopes verify w0 (prior 81), only inverse verifies w1 (prior 18), neither verifies w2.

                                                            Scope ambiguity boosts the partial world: with both scopes active, L₁(w=1) exceeds its surface-only value (inverse scope verifies w=1).

                                                            S₂ endorsement predictions #

                                                            The endorsement ordering w0 > w1 > w2 is robust across all Figure 2 configurations (even where L₁ itself reverses, as under b_suc = 0.9: per-world renormalization restores it). Each ordering is two cross-world comparisons of the endorsement distribution.

                                                            QUD manipulation (Figure 2, center panel): endorsement at the partial world increases none? < how-many? < all? (paper values .38 < .48 < .63) — all? is fully resolved by either scope, so favoring it makes the ambiguous utterance maximally useful. Matches the adult data of Song et al. 2021 reproduced as the paper's Figure 4.

                                                            The structural face: general α #

                                                            The same model on the RSA operator face, parametric in the rationality α and the prior parameters — the general theorems the kernel instances above sample.

                                                            The uniform world prior #

                                                            Uniform world prior (worldPriorAt below is the paper-faithful parametric version).

                                                            Equations
                                                            Instances For

                                                              L0 as RSA.L0OfBoolMeaning #

                                                              uttMeaning lat.scope u w is Bool-valued, so L0 is uniform on the extension. Each scope reading induces its own L0 distribution (the meaning function's first argument is ScopeReading, not just Utt).

                                                              @[reducible, inline]

                                                              Extension of uttMeaning s u: the worlds where u is true under scope s.

                                                              Equations
                                                              Instances For
                                                                noncomputable def ScontrasPearl2021.EveryNot.L0 (s : ScopeReading) (u : Utt) :

                                                                Literal listener: uniform on the extension of uttMeaning lat.scope u.

                                                                Equations
                                                                Instances For
                                                                  @[simp]
                                                                  theorem ScontrasPearl2021.EveryNot.mem_support_L0_iff (s : ScopeReading) (u : Utt) (w : JumpOutcome) :
                                                                  w (L0 s u).support uttMeaning s u w = true
                                                                  theorem ScontrasPearl2021.EveryNot.L0_apply_of_true {s : ScopeReading} {u : Utt} {w : JumpOutcome} (h : uttMeaning s u w = true) :
                                                                  (L0 s u) w = (↑(extension s u).card)⁻¹
                                                                  theorem ScontrasPearl2021.EveryNot.L0_apply_of_false {s : ScopeReading} {u : Utt} {w : JumpOutcome} (h : uttMeaning s u w true) :
                                                                  (L0 s u) w = 0

                                                                  QUD projection facts on ℝ≥0∞ #

                                                                  theorem ScontrasPearl2021.EveryNot.qudProjectE_ne_top {q : QUD} {f : JumpOutcomeENNReal} {w : JumpOutcome} (hf : ∀ (w : JumpOutcome), f w ) :
                                                                  qProj q f w

                                                                  The projection at w under QUD q is bounded above by the total mass of f (a finite sum of pieces of Σ f). Used to discharge ≠ ∞.

                                                                  theorem ScontrasPearl2021.EveryNot.qudProjectE_self_ge {q : QUD} {f : JumpOutcomeENNReal} (w : JumpOutcome) :
                                                                  f w qProj q f w

                                                                  The projection of L0 includes the mass at w itself (since w is in its own equivalence class for every QUD). Used to derive positivity of the rpow speaker score at the witness world.

                                                                  theorem ScontrasPearl2021.EveryNot.qudProjectE_ne_zero_of_self {q : QUD} {f : JumpOutcomeENNReal} {w : JumpOutcome} (h : f w 0) :
                                                                  qProj q f w 0

                                                                  If L0 is non-zero at w, the QUD-projected sum is non-zero at w.

                                                                  S1g — speaker conditional on (latent, world) #

                                                                  S1g lat w u ∝ (qProj lat.qud (L0 lat.scope u) w)^α. The cover witness is the null utterance: its L0 is uniform on Finset.univ, so the projection is positive at every w (every QUD class contains some world where null's L0 is positive — and null's L0 is positive everywhere).

                                                                  noncomputable def ScontrasPearl2021.EveryNot.s1Weight (α : ) (lat : Latent) (w : JumpOutcome) (u : Utt) :
                                                                  ENNReal

                                                                  The unnormalised score: (qProj lat.qud (L0 lat.scope u) w)^α.

                                                                  Equations
                                                                  Instances For
                                                                    theorem ScontrasPearl2021.EveryNot.s1Weight_null_ne_zero {α : } ( : 0 < α) (lat : Latent) (w : JumpOutcome) :
                                                                    s1Weight α lat w Utt.null 0
                                                                    theorem ScontrasPearl2021.EveryNot.s1Weight_ne_top {α : } ( : 0 α) (lat : Latent) (w : JumpOutcome) (u : Utt) :
                                                                    s1Weight α lat w u
                                                                    theorem ScontrasPearl2021.EveryNot.s1Weight_tsum_ne_zero {α : } ( : 0 < α) (lat : Latent) (w : JumpOutcome) :
                                                                    ∑' (u : Utt), s1Weight α lat w u 0
                                                                    theorem ScontrasPearl2021.EveryNot.s1Weight_tsum_ne_top {α : } ( : 0 α) (lat : Latent) (w : JumpOutcome) :
                                                                    ∑' (u : Utt), s1Weight α lat w u
                                                                    noncomputable def ScontrasPearl2021.EveryNot.S1g {α : } ( : 0 < α) (lat : Latent) (w : JumpOutcome) :
                                                                    PMF Utt

                                                                    Pragmatic speaker conditioned on (latent, world).

                                                                    Equations
                                                                    Instances For
                                                                      theorem ScontrasPearl2021.EveryNot.mem_support_S1g_iff {α : } ( : 0 < α) (lat : Latent) (w : JumpOutcome) (u : Utt) :
                                                                      u (S1g lat w).support s1Weight α lat w u 0
                                                                      theorem ScontrasPearl2021.EveryNot.S1g_null_ne_zero {α : } ( : 0 < α) (lat : Latent) (w : JumpOutcome) :
                                                                      (S1g lat w) Utt.null 0

                                                                      Marginal speaker — PMF.bind over the latent prior #

                                                                      The product latent is scope × QUD (flattened to Latent). PMF.bind against a latentPrior : PMF Latent is mathlib's idiom for marginalising over a chained random variable — exactly what's needed here.

                                                                      noncomputable def ScontrasPearl2021.EveryNot.marginalSpeaker {α : } ( : 0 < α) (latentPrior : PMF Latent) (w : JumpOutcome) :
                                                                      PMF Utt

                                                                      Speaker marginalised over latent state.

                                                                      Equations
                                                                      Instances For
                                                                        theorem ScontrasPearl2021.EveryNot.marginalSpeaker_null_ne_zero {α : } ( : 0 < α) {latentPrior : PMF Latent} {lat : Latent} (hlat : latentPrior lat 0) (w : JumpOutcome) :
                                                                        (marginalSpeaker latentPrior w) Utt.null 0

                                                                        The cover witness lifts to the marginal speaker: if any latent has positive prior mass and S1g is non-zero on null, the marginal speaker is non-zero on null. Used to discharge marginal ≠ 0 for L1 at u = null.

                                                                        L1 — Bayesian inversion via PMF.posterior #

                                                                        theorem ScontrasPearl2021.EveryNot.L1_marginal_null_ne_zero {α : } ( : 0 < α) {latentPrior : PMF Latent} {lat : Latent} (hlat : latentPrior lat 0) :
                                                                        theorem ScontrasPearl2021.EveryNot.marginalSpeaker_everyNot_at_zero_ne_zero {α : } ( : 0 < α) {latentPrior : PMF Latent} {lat : Latent} (hlat : latentPrior lat 0) :

                                                                        The everyNot utterance also has L1-marginal cover: at world .zero, both scope readings make everyNot true, so L0 puts positive mass there, S1g(everyNot|lat,.zero) > 0 for every lat (since qudProject ≥ L0(.zero) > 0), and the marginal speaker is positive on everyNot at .zero.

                                                                        theorem ScontrasPearl2021.EveryNot.L1_marginal_everyNot_ne_zero {α : } ( : 0 < α) {latentPrior : PMF Latent} {lat : Latent} (hlat : latentPrior lat 0) :
                                                                        noncomputable def ScontrasPearl2021.EveryNot.L1 {α : } ( : 0 < α) (latentPrior : PMF Latent) (u : Utt) (hMarg : PMF.marginal (marginalSpeaker latentPrior) worldPrior u 0) :

                                                                        Pragmatic listener: PMF.posterior of the latent-marginalised speaker against the world prior. The "L1 = Bayesian inversion" claim is true by construction (PMF.posterior IS Bayes' rule).

                                                                        Equations
                                                                        Instances For
                                                                          theorem ScontrasPearl2021.EveryNot.mem_support_L1_iff {α : } ( : 0 < α) (latentPrior : PMF Latent) (u : Utt) (hMarg : PMF.marginal (marginalSpeaker latentPrior) worldPrior u 0) (w : JumpOutcome) :
                                                                          w (L1 latentPrior u hMarg).support worldPrior w 0 (marginalSpeaker latentPrior w) u 0

                                                                          The general-α baseline orderings #

                                                                          General-α companions of baseline_l1_ordering: the L₁ orderings hold for every α > 0 and any latentPrior with positive mass everywhere. The structural shell: posterior_lt_iff_kernel_lt_of_uniform cancels the L1 marginal and the uniform world prior, PMF.bind_lt_bind reduces the marginal speaker to per-latent S1g comparisons, and each latent case is a vacuous zero, an equality of score functions, or rpow monotonicity.

                                                                          Surface-scope-favored latent prior: every latent has positive mass. Used as the default latentPrior for the findings below.

                                                                          Equations
                                                                          Instances For

                                                                            extension X .null = Finset.univ for both scopes — null is true everywhere. Structurally generic: constructs cover witnesses for universal-extension utterances.

                                                                            L0 values at each (scope, utterance, world) — the leaves every comparison below reduces to.

                                                                            At .surfHowMany, surface scope makes .everyNot false at .one, so the speaker score vanishes there but not at .zero.

                                                                            Same shape at .surfNone: the none? projection at .one is L0 .one + L0 .two = 0.

                                                                            Per-latent comparison for the w0-vs-w1 ordering: no latent gives .everyNot more mass at .one than at .zero, strictly less at .surfHowMany. Each case is a vacuous zero, an equality of score functions, or of projections lifted through rpow.

                                                                            Baseline L1 ordering L1(zero | everyNot) > L1(one | everyNot) for every α > 0: cancel the marginal and the uniform world prior, then compare the marginal speakers per latent.

                                                                            At .invHowMany, inverse scope makes .everyNot false at .two, so the speaker score vanishes there but not at .one.

                                                                            Per-latent comparison for the w1-vs-w2 ordering: five cases are vacuous zeros at .two, .invNone is an equality.

                                                                            Baseline L1 ordering L1(one | everyNot) > L1(two | everyNot) for every α > 0. Same discharge as baseline_L1_zero_gt_one.

                                                                            Scope collapse under QUD = all? (paper §3.2, restated §5.1) #

                                                                            The paper's central explanatory move (p. 17, 29-30): when QUD = all? is favored, BOTH scope readings of "every horse didn't jump" answer the QUD identically with "no, not all succeeded". This collapses the scope distinction at the speaker layer — the structural mechanism behind pragmatic dominance (the scope prior becoming nearly irrelevant).

                                                                            Formalized at three layers: qProj .all_ is scope-independent at every utterance and world; hence S1g hα .surfAll = S1g hα .invAll as PMFs; hence the surface/inverse all?-latents contribute interchangeably to the marginal speaker.

                                                                            Under QUD = all?, the projected L0 mass is scope-invariant at every utterance and world: the raw L0s differ (surface concentrates on .zero, inverse splits over .zero, .one) but the all?-cell sums agree.

                                                                            Under QUD = all?, the speaker S1g is identical for surface and inverse scope readings (at every world).

                                                                            Direct corollary of the L0 invariance lifted through PMF.normalize: the score functions are pointwise equal (since s1Weight only depends on lat.qud and lat.scope through qProj which collapses the scope distinction), so the normalized PMFs are equal.

                                                                            Scope-prior irrelevance under QUD = all? #

                                                                            The headline structural consequence of the speaker collapse: when the latent prior is split between .surfAll and .invAll, the contribution of these two latents to marginalSpeaker depends only on the SUM of their prior weights, not the individual values. Direct corollary of S1g_all_qud_scope_invariant

                                                                            This is the structural mechanism behind the pragmatic-dominance claim: shifting prior mass between .invAll and .surfAll doesn't change the all?-QUD speaker behavior.

                                                                            theorem ScontrasPearl2021.EveryNot.marginalSpeaker_surfAll_invAll_combine {α : } ( : 0 < α) (latentPrior : PMF Latent) (w : JumpOutcome) (u : Utt) :
                                                                            latentPrior Latent.surfAll * (S1g Latent.surfAll w) u + latentPrior Latent.invAll * (S1g Latent.invAll w) u = (latentPrior Latent.surfAll + latentPrior Latent.invAll) * (S1g Latent.surfAll w) u

                                                                            Under QUD = all?, the .surfAll and .invAll contributions to marginalSpeaker combine as a single sum-weighted term — their individual prior weights don't matter, only the total.

                                                                            Proof: S1g_all_qud_scope_invariant + ENNReal add_mul.

                                                                            The general-α QUD ordering (open) #

                                                                            The kernel-checked s2_qud_ordering above proves Figure 2's center panel at the paper's exact parameters (α = 1, b_suc = 0.5, 18:1 QUD bias). The general-α, parametric-prior statement — endorsement at .one ordered across qudPriorAt values favoring none? < how-many? < all? — remains open: the scope-collapse theorems above supply the all?-latent structure, but the cross-prior comparison needs ENNReal arithmetic on the closed-form chain (module-docstring TODO).

                                                                            A related non-theorem, worth recording: endorsement monotonicity in b_suc (Figure 2, left) is NOT factor-wise — worldPriorAt b_suc .one equals 2·b_suc·(1 − b_suc), symmetric in b_suc ↔ 1 − b_suc and peaked at 1/2 — so the observed monotone endorsement (.29/.50/.80) is an emergent property of the full chain: as b_suc → 1 the utterance gains informativity at .one by ruling out the high-prior .two. Any formalization must go through the full chain, e.g. as a limit statement.

                                                                            The two-not model (§4) #

                                                                            Utterances: null (silence) or "two horses didn't jump".

                                                                            Instances For
                                                                              @[implicit_reducible]
                                                                              Equations
                                                                              Equations
                                                                              • One or more equations did not get rendered due to their size.
                                                                              Instances For

                                                                                QUDs for the two-not model (paper (7)). Five partitions over the 5-world domain. The two numeral-specific QUDs (two=?, two≥?) are added because explicitly mentioning a numeral makes that cardinality potentially relevant to the topic of conversation.

                                                                                Instances For
                                                                                  @[implicit_reducible]
                                                                                  Equations
                                                                                  Equations
                                                                                  • One or more equations did not get rendered due to their size.
                                                                                  Instances For
                                                                                    @[implicit_reducible]
                                                                                    Equations
                                                                                    • One or more equations did not get rendered due to their size.

                                                                                    Flattened latent variable: scope reading × QUD. 2 scopes × 5 QUDs = 10 constructors.

                                                                                    Instances For
                                                                                      @[implicit_reducible]
                                                                                      Equations
                                                                                      Equations
                                                                                      • One or more equations did not get rendered due to their size.
                                                                                      Instances For
                                                                                        @[implicit_reducible]
                                                                                        Equations
                                                                                        • One or more equations did not get rendered due to their size.

                                                                                        Truth conditions and compositional grounding #

                                                                                        RSA meaning for the two-not model, parameterized by numeral reading. Null utterance is always true (uninformative baseline).

                                                                                        Equations
                                                                                        Instances For

                                                                                          4-horse domain for grounding two-not truth conditions in numeral quantifier semantics.

                                                                                          Instances For
                                                                                            @[implicit_reducible]
                                                                                            Equations
                                                                                            @[implicit_reducible]
                                                                                            Equations
                                                                                            • One or more equations did not get rendered due to their size.

                                                                                            Restrictor: all entities are horses (trivial for this model).

                                                                                            Equations
                                                                                            Instances For

                                                                                              "Two horses didn't jump" as a ScopeDerivation under exact semantics: a single syntactic form with multiple semantic values indexed by scope.

                                                                                              Equations
                                                                                              • One or more equations did not get rendered due to their size.
                                                                                              Instances For

                                                                                                "Two horses didn't jump" as a ScopeDerivation under at-least semantics.

                                                                                                Equations
                                                                                                • One or more equations did not get rendered due to their size.
                                                                                                Instances For

                                                                                                  The exact two-not scope pair has INDEPENDENT readings: neither entails the other. This independence makes exact numerals diagnostic for the isomorphism effect — unlike universals, which have nested readings.

                                                                                                  The kernel face: exact-ℚ scores at the paper parameters #

                                                                                                  Literal listener (fn. 6: no world prior in L0).

                                                                                                  Equations
                                                                                                  • One or more equations did not get rendered due to their size.
                                                                                                  Instances For

                                                                                                    Speaker (α = 1; costs cancel).

                                                                                                    Equations
                                                                                                    • One or more equations did not get rendered due to their size.
                                                                                                    Instances For
                                                                                                      def ScontrasPearl2021.TwoNot.l1Score (nr : NumeralReading) (wp : JumpOutcome4ℚ≥0) (sp : ScopeReadingℚ≥0) (qp : QUD5ℚ≥0) (u : Utt) (w : JumpOutcome4) :
                                                                                                      ℚ≥0

                                                                                                      Joint pragmatic-listener world score.

                                                                                                      Equations
                                                                                                      Instances For
                                                                                                        def ScontrasPearl2021.TwoNot.l1Post (nr : NumeralReading) (wp : JumpOutcome4ℚ≥0) (sp : ScopeReadingℚ≥0) (qp : QUD5ℚ≥0) (u : Utt) :
                                                                                                        JumpOutcome4ℚ≥0

                                                                                                        Normalized world posterior.

                                                                                                        Equations
                                                                                                        Instances For

                                                                                                          Uniform QUD prior.

                                                                                                          Equations
                                                                                                          Instances For
                                                                                                            noncomputable def ScontrasPearl2021.TwoNot.s2 (nr : NumeralReading) (w : JumpOutcome4) :
                                                                                                            PMF Utt

                                                                                                            Endorsement speaker S₂ over the two-not listener (baseline priors: b_suc = 0.1, P(inverse) = 0.1, uniform QUDs).

                                                                                                            Equations
                                                                                                            • One or more equations did not get rendered due to their size.
                                                                                                            Instances For

                                                                                                              Endorsement predictions (§4.2, Figure 7) #

                                                                                                              Under exact semantics, surface scope pinpoints w=2 as the unique true world, so baseline endorsement at w=2 is high; under at-least semantics it spreads over {w0,w1,w2} and endorsement is low. The same baseline that gives low 1-of-2 endorsement gives high 2-of-4 endorsement only under exact semantics — the paper's argument for exact numeral meanings.

                                                                                                              Exact semantics: baseline S₂ endorsement at w=2 exceeds 1/2 (Figure 7 right, ≈ .8).

                                                                                                              At-least semantics: baseline S₂ endorsement at w=2 is below 1/2 (Figure 7 left, ≈ .4).

                                                                                                              Exact endorsement at w=2 exceeds at-least endorsement: one true surface world versus three.

                                                                                                              Informativity contrasts #

                                                                                                              The key informativity contrast: under exact semantics, surface scope has exactly 1 true world (w2), while under at-least it has 3 (w0–w2). This drives the endorsement difference via S1 informativity.

                                                                                                              Exact inverse has 4 true worlds (w0,w1,w3,w4) — very uninformative. Since w2 is the only world where surface scope is true, inverse scope contributes nothing at w2 (it's false there), explaining why surface scope dominates the S2 prediction under exact semantics.

                                                                                                              At-least inverse has 2 true worlds (w0,w1) — more informative than exact inverse's 4, but still less informative than exact surface's 1.

                                                                                                              The structural face: exact-vs-at-least necessity (§4.2.2) #

                                                                                                              The paper's strongest contribution to the numeral-semantics literature:

                                                                                                              "the current model requires one more ingredient to account for the 1-of-2 vs 2-of-4 difference in adult behavior: an exact semantics for utterances with numerals (in contrast to an at-least semantics; for discussion, see e.g. Geurts 2006; Breheny 2008)."

                                                                                                              Figure 7 (paper p.27) shows the contrast explicitly: under exact semantics the surface scope of twoNot pinpoints w=2 as the unique true world → high S2 endorsement; under at-least semantics the surface scope is true at multiple worlds {w0, w1, w2} → S2 dilutes across 3 worlds → low endorsement.

                                                                                                              The paper's core empirical move: only with exact semantics can the model reproduce adult endorsement-rate divergence between EveryNot (1-of-2) and TwoNot (2-of-4).

                                                                                                              This section proves the structural foundation: at w=2, the surface-scope twoNot L0 mass is strictly higher under exact semantics than under at-least semantics (a singleton extension {w2} versus {w0, w1, w2}). The endorsement difference proved on the kernel face above (exact_vs_atleast_endorsement and the two threshold theorems) inherits from this concentration.

                                                                                                              Extension of twoNot under each numeral reading #

                                                                                                              @[reducible, inline]

                                                                                                              Extension of uttMeaning nr s u: worlds where u is true under numeral reading nr and scope s.

                                                                                                              Equations
                                                                                                              Instances For

                                                                                                                Under exact semantics, surface twoNot extension is the singleton {w2} (only "exactly 2 didn't jump" is true when exactly 2 jumped).

                                                                                                                Under at-least semantics, surface twoNot extension is {w0, w1, w2} (at least 2 didn't jump iff at most 2 jumped).

                                                                                                                L0 (literal listener) for the TwoNot model #

                                                                                                                Parameterized on numeral reading nr (exact vs at-least), determining the extension's cardinality.

                                                                                                                TwoNot literal listener: uniform on extension under given numeral reading.

                                                                                                                Equations
                                                                                                                Instances For
                                                                                                                  theorem ScontrasPearl2021.TwoNot.L0_4_apply_of_true {nr : NumeralReading} {s : ScopeReading} {u : Utt} {w : JumpOutcome4} (h : uttMeaning nr s u w = true) :
                                                                                                                  (L0_4 nr s u) w = (↑(extension4 nr s u).card)⁻¹
                                                                                                                  theorem ScontrasPearl2021.TwoNot.L0_4_apply_of_false {nr : NumeralReading} {s : ScopeReading} {u : Utt} {w : JumpOutcome4} (h : uttMeaning nr s u w true) :
                                                                                                                  (L0_4 nr s u) w = 0

                                                                                                                  The L0 concentration contrast #

                                                                                                                  At world w2 (2 of 4 jumped), surface scope twoNot L0 mass is strictly higher under exact than under at-least — because the extension cardinality shrinks from 3 to 1. The S2 endorsement difference inherits from this.

                                                                                                                  The structural foundation of the exact-semantics necessity claim: at world w2, surface-scope twoNot L0 is strictly higher under EXACT semantics (1) than under AT-LEAST semantics (1/3).

                                                                                                                  Proof: extension cardinality is 1 (exact) vs 3 (at-least); uniform-on-extension gives 1/1 = 1 vs 1/3.

                                                                                                                  This single L0 fact propagates to S2 endorsement: under exact, S2 puts more mass on .twoNot at w=2 (informative utterance pinpoints the world); under at-least, the L0 dilutes across 3 worlds → less informative → lower S2 endorsement. The structural mechanism behind paper's Figure 7.

                                                                                                                  Vacuous-zero contrast at the divergence worlds #

                                                                                                                  The other side of the exact-vs-at-least divergence: at worlds w0 and w1 (where 0 or 1 horses jumped), surface-scope twoNot is FALSE under exact ("not exactly 2 didn't jump") but TRUE under at-least ("at least 2 didn't jump"). So L0 mass under exact at these worlds is 0; L0 mass under at-least is 1/3 (positive).

                                                                                                                  This is the "dilution" mechanism: at-least's broader extension means L0 mass spreads to "wrong" worlds.

                                                                                                                  At worlds w0 and w1, exact L0 is zero (surface twoNot false), at-least L0 is positive (surface twoNot true).

                                                                                                                  The full endorsement-rate divergence at the paper's parameters is proved on the kernel face above (exact_baseline_endorsement_high, atleast_baseline_endorsement_low, exact_vs_atleast_endorsement); a general-α propagation of the L0 concentration through the 5-world × 10-latent chain remains open (module-docstring TODO).

                                                                                                                  The cross-model asymmetry (§4.2.2) #

                                                                                                                  The paper's key argument: the SAME "baseline" parameters that produce low 1-of-2 endorsement also produce high 2-of-4 endorsement — but only under exact numeral semantics.

                                                                                                                  The models have different world types (JumpOutcome vs JumpOutcome4),
                                                                                                                  so we state this as two separate bounds that together establish the
                                                                                                                  1-of-2 vs 2-of-4 asymmetry:
                                                                                                                  
                                                                                                                  - Every-not baseline: S2(everyNot|w=1) < 1/2 (low)
                                                                                                                  - Two-not exact baseline: S2(twoNot|w=2) > 1/2 (high)
                                                                                                                  - Two-not at-least baseline: S2(twoNot|w=2) < 1/2 (low)
                                                                                                                  
                                                                                                                  Both baselines use b_suc = 0.1 (the two-not one adds P(inv) = 0.1).
                                                                                                                  The asymmetry between the second and third is the argument for exact
                                                                                                                  semantics: changing only the numeral reading flips the prediction. 
                                                                                                                  

                                                                                                                  Every-not baseline endorsement at w=1 is below 1/2: the low end of the 1-of-2 vs 2-of-4 asymmetry, with the same b_suc = 0.1 world prior as the two-not baseline.