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MIPRE.Background.Repetition.CommutingRepetition.Prerounding.Main

The output package of tracial pre-rounding (05_prerounding.tex, prop tracial-prerounding): a finite standard-form algebra N; a finite shared history alphabet Hist (the manuscript's tuples (i, r)); the ideal posterior tuple law Q on Hist × X × Y; unit vectors u_{st} (indexed by the full label rectangle (Hist × X) × (Hist × Y)), x_s, y_t; full POVMs (A_s^a), (B_t^b) in N, Alice's used on the left and Bob's on the right; and one finite shared classical seed with its two local history samplers.

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    noncomputable def CommutingRepetition.PreroundedStrategy.idealCorrelation {X Y A B : Type} [Fintype X] [Fintype Y] [Fintype A] [Fintype B] (P : PreroundedStrategy X Y A B) :
    P.Hist × XP.Hist × YAB

    The ideal pair answer law q_{st}(a,b) = ⟪u_{st}, L(A_s^a) R(B_t^b) u_{st}⟫, defined on the full label rectangle.

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      def CommutingRepetition.PreroundedStrategy.labelLaw {X Y A B : Type} [Fintype X] [Fintype Y] [Fintype A] [Fintype B] (P : PreroundedStrategy X Y A B) (s : P.Hist × X) (t : P.Hist × Y) :

      The label law π on S × T: the pushforward of the ideal posterior tuple law under (h, x, y) ↦ ((h, x), (h, y)) — supported on matching histories. [05_prerounding.tex, label-law-pi]

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        noncomputable def CommutingRepetition.PreroundedStrategy.idealSuccess {X Y A B : Type} [Fintype X] [Fintype Y] [Fintype A] [Fintype B] (P : PreroundedStrategy X Y A B) (G : Game X Y A B) :

        The π-averaged ideal success E_π ∑_{a,b} V(a,b | x(s), y(t)) ⟪u_{st}, L(A_s^a) R(B_t^b) u_{st}⟫. [05_prerounding.tex, eq prerounding-ideal-success]

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          noncomputable def CommutingRepetition.PreroundedStrategy.alignment {X Y A B : Type} [Fintype X] [Fintype Y] [Fintype A] [Fintype B] (P : PreroundedStrategy X Y A B) :

          The alignment defect Δ = E_π(‖u_{st} − x_s‖² + ‖u_{st} − y_t‖²). [05_prerounding.tex, eq prerounding-delta]

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            def CommutingRepetition.PreroundedStrategy.JA {X Y A B : Type} [Fintype X] [Fintype Y] [Fintype A] [Fintype B] (P : PreroundedStrategy X Y A B) (G : Game X Y A B) (h : P.Hist) (x : X) (y : Y) :

            The locally generated Alice tuple law J_A: the exact law of (r_A(ω, x), x, y) when ω ∼ ν and (x, y) ∼ μ. [05_prerounding.tex, eq prerounding-tv context; 07_main_theorem.tex, "The exact Alice tuple marginal in the actual classical experiment is J_A"]

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              def CommutingRepetition.PreroundedStrategy.JB {X Y A B : Type} [Fintype X] [Fintype Y] [Fintype A] [Fintype B] (P : PreroundedStrategy X Y A B) (G : Game X Y A B) (h : P.Hist) (x : X) (y : Y) :

              The locally generated Bob tuple law J_B: the exact law of (r_B(ω, y), x, y).

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                The history mismatch probability Pr[r_A ≠ r_B] under ω ∼ ν, (x, y) ∼ μ. [05_prerounding.tex, eq prerounding-mismatch]

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                  The tuple law Q flattened to the tuple type, for divergence and total-variation statements.

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                    def CommutingRepetition.PreroundedStrategy.JAflat {X Y A B : Type} [Fintype X] [Fintype Y] [Fintype A] [Fintype B] (P : PreroundedStrategy X Y A B) (G : Game X Y A B) (t : P.Hist × X × Y) :

                    J_A flattened to the tuple type.

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                      def CommutingRepetition.PreroundedStrategy.JBflat {X Y A B : Type} [Fintype X] [Fintype Y] [Fintype A] [Fintype B] (P : PreroundedStrategy X Y A B) (G : Game X Y A B) (t : P.Hist × X × Y) :

                      J_B flattened to the tuple type.

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                        theorem CommutingRepetition.PreroundedStrategy.sum_labelLaw_mul {X Y A B : Type} [Fintype X] [Fintype Y] [Fintype A] [Fintype B] (P : PreroundedStrategy X Y A B) (f : P.Hist × XP.Hist × Y) :
                        s : P.Hist × X, t : P.Hist × Y, P.labelLaw s t * f s t = h : P.Hist, x : X, y : Y, P.Q h x y * f (h, x) (h, y)

                        Master conversion: a π-average over the label rectangle collapses to a Q-average over tuples, since labelLaw is supported on matching histories.

                        theorem CommutingRepetition.PreroundedStrategy.labelLaw_nonneg {X Y A B : Type} [Fintype X] [Fintype Y] [Fintype A] [Fintype B] (P : PreroundedStrategy X Y A B) (s : P.Hist × X) (t : P.Hist × Y) :
                        0 P.labelLaw s t
                        theorem CommutingRepetition.PreroundedStrategy.labelLaw_sum {X Y A B : Type} [Fintype X] [Fintype Y] [Fintype A] [Fintype B] (P : PreroundedStrategy X Y A B) :
                        s : P.Hist × X, t : P.Hist × Y, P.labelLaw s t = 1

                        The label law is a probability law on the rectangle.

                        The abstract π-alignment of the package's data is its alignment.

                        theorem CommutingRepetition.PreroundedStrategy.Qflat_sum {X Y A B : Type} [Fintype X] [Fintype Y] [Fintype A] [Fintype B] (P : PreroundedStrategy X Y A B) :
                        t : P.Hist × X × Y, P.Qflat t = 1
                        theorem CommutingRepetition.PreroundedStrategy.sum_JAflat_mul {X Y A B : Type} [Fintype X] [Fintype Y] [Fintype A] [Fintype B] (P : PreroundedStrategy X Y A B) (G : Game X Y A B) (f : P.Hist × X × Y) :
                        t : P.Hist × X × Y, P.JAflat G t * f t = ω : P.Seed, x : X, y : Y, P.ν ω * G.questionWeight x y * f (P.rA ω x, x, y)

                        Pushforward identity for the locally generated Alice law: a J_A-average over tuples is the seeded-experiment average (ω ∼ ν, (x,y) ∼ μ, tuple (r_A(ω,x), x, y)).

                        theorem CommutingRepetition.PreroundedStrategy.JAflat_nonneg {X Y A B : Type} [Fintype X] [Fintype Y] [Fintype A] [Fintype B] (P : PreroundedStrategy X Y A B) (G : Game X Y A B) (t : P.Hist × X × Y) :
                        0 P.JAflat G t
                        theorem CommutingRepetition.PreroundedStrategy.JAflat_sum {X Y A B : Type} [Fintype X] [Fintype Y] [Fintype A] [Fintype B] (P : PreroundedStrategy X Y A B) (G : Game X Y A B) :
                        t : P.Hist × X × Y, P.JAflat G t = 1
                        theorem CommutingRepetition.weighted_tracial_prerounding {X Y A B : Type} [Fintype X] [Fintype Y] [Fintype A] [Fintype B] [Nonempty X] [Nonempty Y] [Nonempty A] [Nonempty B] (G : Game X Y A B) (hQ : ∀ (x : X) (y : Y) (a : A) (b : B), ∃ (r : ), G.payoff x y a b = r) (n : ) (hn : 1 n) (Trep : TracialStrategy (Fin nX) (Fin nY) (Fin nA) (Fin nB)) {ε γ : } (hε0 : 0 < ε) (hε1 : ε 1) ( : γ ε / 8) ( : Real.exp (-(γ * n)) < (G.repeat n).win Trep.correlation) :
                        ∃ (P : PreroundedStrategy X Y A B) (η : ), 0 η η 8 * γ * ((ε + Real.log ((Fintype.card A) * (Fintype.card B))) / ε) 1 - ε / 4 P.idealSuccess G P.alignment 16 * η (∀ (t : P.Hist × X × Y), P.JAflat G t = 0P.Qflat t = 0) (∀ (t : P.Hist × X × Y), P.JBflat G t = 0P.Qflat t = 0) Pinsker.finiteRelativeEntropy P.Qflat (P.JAflat G) 3 * η Pinsker.finiteRelativeEntropy P.Qflat (P.JBflat G) 3 * η Pinsker.finiteTotalVariation P.Qflat (P.JAflat G) (3 * η / 2) Pinsker.finiteTotalVariation P.Qflat (P.JBflat G) (3 * η / 2) P.mismatchProb G 4 * (3 * η / 2)

                        Weighted tracial pre-rounding (nodes 1.2 + 1.6.2; 05_prerounding.tex, prop tracial-prerounding, run as modified by 07_main_theorem.tex sec 7.4 for rational payoff tables): the referee declares acceptance per coordinate with a fresh finite private coin of bias V(aᵢ, bᵢ | xᵢ, yᵢ) — possible exactly because the payoffs are rational — and the coins are never revealed, so no effect, sampler, or label depends on them. The Section 5 machinery runs with the core indicator replaced by the weight w_D ∈ [0,1] (eq private-coin-core-weight), the accepted-word budget by the weighted entropy inequality w·H₁(a) ≤ H₁(w·a) plus log-sum (eq weighted-accepted-word-entropy), and the history budget by data processing from the private-coin space; the manuscript notes every constant is unchanged, so the conclusion is form-identical to the predicate case, of which this statement is the generalization (the predicate case is the specialization to {0,1}-valued — hence rational — payoffs). Conclusion shape as in tracial_prerounding below.

                        theorem CommutingRepetition.tracial_prerounding {X Y A B : Type} [Fintype X] [Fintype Y] [Fintype A] [Fintype B] [Nonempty X] [Nonempty Y] [Nonempty A] [Nonempty B] (G : Game X Y A B) (hV : G.IsPredicate) (n : ) (hn : 1 n) (Trep : TracialStrategy (Fin nX) (Fin nY) (Fin nA) (Fin nB)) {ε γ : } (hε0 : 0 < ε) (hε1 : ε 1) ( : γ ε / 8) ( : Real.exp (-(γ * n)) < (G.repeat n).win Trep.correlation) :
                        ∃ (P : PreroundedStrategy X Y A B) (η : ), 0 η η 8 * γ * ((ε + Real.log ((Fintype.card A) * (Fintype.card B))) / ε) 1 - ε / 4 P.idealSuccess G P.alignment 16 * η (∀ (t : P.Hist × X × Y), P.JAflat G t = 0P.Qflat t = 0) (∀ (t : P.Hist × X × Y), P.JBflat G t = 0P.Qflat t = 0) Pinsker.finiteRelativeEntropy P.Qflat (P.JAflat G) 3 * η Pinsker.finiteRelativeEntropy P.Qflat (P.JBflat G) 3 * η Pinsker.finiteTotalVariation P.Qflat (P.JAflat G) (3 * η / 2) Pinsker.finiteTotalVariation P.Qflat (P.JBflat G) (3 * η / 2) P.mismatchProb G 4 * (3 * η / 2)

                        Tracial pre-rounding (node 1.2; 05_prerounding.tex, prop tracial-prerounding). Standing assumption of Section 5: the payoff is a predicate. Given a tracially embeddable strategy for G^{⊗n} with success θ > e^{−γn}, 0 < ε ≤ 1, γ ≤ ε/8, and ℓ = log(|A||B|), there is a pre-rounded package and an η ≤ 8γ(ε + ℓ)/ε with: ideal success ≥ 1 − ε/4; alignment Δ ≤ 16η; D(Q‖J_A), D(Q‖J_B) ≤ 3η (with the absolute continuity finiteness implies); d_TV(Q, J_A), d_TV(Q, J_B) ≤ κ = √(3η/2); and sampler mismatch Pr[r_A ≠ r_B] ≤ 4κ. The samplers' marginals ARE J_A, J_B by definition of the package. Obtained from the weighted form above: a predicate payoff is 0 or 1, both rational.