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MIPRE.Background.LIDT.MIPStarRE.LDT.Test.StrategyCore

Section 3 — Strategy core #

Base state-invariance and strategy structures for the low individual degree test.

def MIPStarRE.LDT.swapDensity {ι : Type u_1} (M : Quantum.Op (ι × ι)) :
Quantum.Op (ι × ι)

The SWAP reindexing on ι × ι: permutes the two tensor factors. swapDensity M (i₁,i₂) (j₁,j₂) = M (i₂,i₁) (j₂,j₁).

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    swapDensity is equal to reindexing by the product-commutation equivalence.

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    theorem MIPStarRE.LDT.swapDensity_add {ι : Type u_1} (X Y : Quantum.Op (ι × ι)) :
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    theorem MIPStarRE.LDT.swapDensity_smul {ι : Type u_1} (c : ) (X : Quantum.Op (ι × ι)) :
    theorem MIPStarRE.LDT.swapDensity_mul {ι : Type u_1} [Fintype ι] (X Y : Quantum.Op (ι × ι)) :

    swapDensity preserves matrix multiplication.

    theorem MIPStarRE.LDT.ev_swapDensity_of_density_fixed {ι : Type u_1} [Fintype ι] [DecidableEq ι] (ψ : QuantumState (ι × ι)) (hfix : swapDensity ψ.density = ψ.density) (Z : Quantum.Op (ι × ι)) :
    ev ψ (swapDensity Z) = ev ψ Z
    theorem MIPStarRE.LDT.ev_opTensor_swap_of_density_fixed {ι : Type u_1} [Fintype ι] [DecidableEq ι] (ψ : QuantumState (ι × ι)) (hfix : swapDensity ψ.density = ψ.density) (X Y : Quantum.Op ι) :
    ev ψ (opTensor X Y) = ev ψ (opTensor Y X)
    theorem MIPStarRE.LDT.qBipartiteMatchMass_symm_of_density_fixed {ι : Type u_1} [Fintype ι] [DecidableEq ι] (ψ : QuantumState (ι × ι)) (hfix : swapDensity ψ.density = ψ.density) {Outcome : Type u_2} [Fintype Outcome] (A B : SubMeas Outcome ι) :
    theorem MIPStarRE.LDT.qBipartiteConsDefect_symm_of_density_fixed {ι : Type u_1} [Fintype ι] [DecidableEq ι] (ψ : QuantumState (ι × ι)) (hfix : swapDensity ψ.density = ψ.density) {Outcome : Type u_2} [Fintype Outcome] (A B : SubMeas Outcome ι) :
    theorem MIPStarRE.LDT.consRel_symm_of_density_fixed {ι : Type u_1} [Fintype ι] [DecidableEq ι] (ψ : QuantumState (ι × ι)) (hfix : swapDensity ψ.density = ψ.density) {Question : Type u_2} {Outcome : Type u_3} [Fintype Outcome] (𝒟 : Distribution Question) (A B : IdxSubMeas Question Outcome ι) (δ : Error) :
    ConsRel ψ 𝒟 A B δConsRel ψ 𝒟 B A δ
    structure MIPStarRE.LDT.PermInvState {ι : Type u_1} [Fintype ι] [DecidableEq ι] (ψ : QuantumState (ι × ι)) :

    Permutation-invariance for a bipartite state on ι × ι.

    The primary datum is that the density operator is fixed by the SWAP reindexing, swapDensity ψ.density = ψ.density. We also cache the frequently used one-sided expectation consequence ev ψ (leftTensor M) = ev ψ (rightTensor M). This matches the symmetric-strategy construction used in the paper (Section 3) and exposes enough symmetry to swap fully bipartite consistency expressions.

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      Direct outcome-level covariance for axis-parallel-line measurements.

      Rebasing a line question by t and reparametrizing an outcome polynomial by the same translation leaves the corresponding projector unchanged.

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        Direct outcome-level covariance for diagonal-line measurements.

        Rebasing a line question by t and reparametrizing an outcome polynomial by the same translation leaves the corresponding projector unchanged.

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          Reparametrization invariance for diagonal-line measurements: evaluating a rebased line at zeroCoord agrees outcome-wise with evaluating the original line at the rebasing parameter.

          At the answer level, the geometric identity is DiagonalLinePolynomial.reparamAt_apply_zero. This predicate is stronger: it asserts that the measurement family itself is covariant under rebasing the question index.

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            Reparametrization invariance for axis-parallel-line measurements: evaluating a rebased line at zeroCoord agrees outcome-wise with evaluating the original line at the rebasing parameter.

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              noncomputable def MIPStarRE.LDT.AxisParallelLine.transportMeasurement {params : Parameters} [FieldModel params.q] {ι : Type u_1} [Fintype ι] [DecidableEq ι] (M : ProjMeas (AxisLinePolynomial params) ι) (t : Fq params) :

              Transport an axis-parallel-line measurement along rebasing of the line question by translating its polynomial outcomes.

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                Evaluating a transported axis-line measurement at zeroCoord agrees with reading the original measurement at the rebasing parameter.

                noncomputable def MIPStarRE.LDT.DiagonalLine.transportMeasurement {params : Parameters} [FieldModel params.q] {ι : Type u_1} [Fintype ι] [DecidableEq ι] (M : ProjMeas (DiagonalLinePolynomial params) ι) (t : Fq params) :

                Transport a diagonal-line measurement along rebasing of the line question by translating its polynomial outcomes.

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                  Evaluating a transported diagonal-line measurement at zeroCoord agrees with reading the original measurement at the rebasing parameter.

                  Stronger rebasing compatibility for axis-parallel-line measurements: the measurement indexed by the rebased line is equal to the transport of the original measurement along the answer reparametrization equivalence.

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                    Stronger rebasing compatibility for diagonal-line measurements: the measurement indexed by the rebased line is equal to the transport of the original measurement along the answer reparametrization equivalence.

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                      Transport-level axis-parallel covariance implies direct outcome covariance.

                      Transport-level diagonal covariance implies direct outcome covariance.

                      Direct axis-parallel outcome covariance implies transport-level covariance.

                      Direct diagonal outcome covariance implies transport-level covariance.

                      Direct outcome covariance and transport-level covariance are equivalent for axis-parallel-line projective measurements.

                      Direct outcome covariance and transport-level covariance are equivalent for diagonal-line projective measurements.

                      The stronger transport-level axis-parallel compatibility implies the older outcome-level reparametrization invariant predicate.

                      The stronger transport-level diagonal compatibility implies the older outcome-level reparametrization invariant predicate.

                      structure MIPStarRE.LDT.AxisParallelCovariantMeasurement (params : Parameters) [FieldModel params.q] (ι : Type u_1) [Fintype ι] [DecidableEq ι] :
                      Type (max u_1 u_2)

                      Axis-parallel line measurements bundled with the stronger transport-level rebasing covariance.

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                        A covariant wrapper automatically satisfies the older evaluation-level rebasing invariant.

                        structure MIPStarRE.LDT.DiagonalCovariantMeasurement (params : Parameters) [FieldModel params.q] (ι : Type u_1) [Fintype ι] [DecidableEq ι] :
                        Type (max u_1 u_2)

                        Diagonal line measurements bundled with the stronger transport-level rebasing covariance.

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                          A covariant wrapper automatically satisfies the older evaluation-level rebasing invariant.

                          Transport covariance for diagonal-line measurements whose answers are the paper-level line functions.

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                            Diagonal-line measurements with paper-level function answers, bundled with transport-level rebasing covariance.

                            This parallel API is intended for the paper-faithful restriction redesign: unlike DiagonalLinePolynomial, the function-answer alphabet admits a total slice append/restrict equivalence.

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                              structure MIPStarRE.LDT.AnswerSymStrat (params : Parameters) [FieldModel params.q] (ι : Type u_1) [Fintype ι] [DecidableEq ι] :
                              Type (max u_1 u_2)

                              Paper-level symmetric strategy data whose diagonal-line answers are functions.

                              This parallel structure is the target shape for the restriction redesign in Section 6: restricting an ambient diagonal line to a slice is total for function answers, unlike the current degree-bounded DiagonalLinePolynomial alphabet.

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                                structure MIPStarRE.LDT.SymStrat (params : Parameters) [FieldModel params.q] (ι : Type u_1) [Fintype ι] [DecidableEq ι] :
                                Type (max u_1 u_2)

                                Paper-local symmetric strategy data.

                                The line-measurement fields are bundled as transport-covariant wrappers: rebasing the question index is required to agree with transporting the projective measurement along the corresponding answer reparametrization equivalence. This is stronger than the older evaluation-level formulas at zeroCoord, but those formulas remain available as derived lemmas via AxisParallelCovariantMeasurement.reparamInvariant and DiagonalCovariantMeasurement.reparamInvariant.

                                The isNormalized field records that the bipartite state's density operator has normalized trace 1. For pure states, this coincides with the usual unit-vector condition (⟨ψ|ψ⟩ = 1) used in the paper. Bundling normalization with the strategy avoids threading a state.IsNormalized hypothesis through every downstream consumer (pasting cascade, triangleSub users, self-improvement helpers).

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                                  Encoded samples (u, i) for the axis-parallel lines test. The paper samples a random point u ∈ F_q^m and a coordinate i ∈ {1, …, m}. In Lean, Fin params.m represents the 0-indexed coordinates {0, …, m - 1}, corresponding to the paper's 1-indexed choice. The sample forms the axis-parallel line through u in that coordinate direction.

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                                    def MIPStarRE.LDT.extendRestrictedDirection {params : Parameters} [FieldModel params.q] (j : Fin params.m) (freeCoords : Fin (j + 1)Fq params) :
                                    Point params

                                    Extend restricted direction coordinates to a full direction vector. For restriction index j (0-indexed), the first j + 1 coordinates are the given free coordinates and the remaining are zero. This matches the paper's convention that v has its last m − i coordinates zero, where i = j + 1.

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                                      Encoded samples (u, freeCoords) for the j-restricted diagonal lines test. The base point u ∈ F_q^m and the free coordinates of the restricted direction (first j + 1 coordinates; rest are zero). The full diagonal test averages over j ∈ {0, …, m − 1}.

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                                        The restricted diagonal sample space is nonempty.

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                                        noncomputable abbrev MIPStarRE.LDT.axisParallelPointAnswerFamilyOf {params : Parameters} [FieldModel params.q] {ι : Type u_1} [Fintype ι] [DecidableEq ι] (pointMeasurement : IdxProjMeas (Point params) (Fq params) ι) :
                                        IdxSubMeas (AxisParallelTestSample params) (Fq params) ι

                                        Sampled point answers in the axis-parallel lines test, obtained from a point measurement.

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                                          noncomputable abbrev MIPStarRE.LDT.axisParallelLineAnswerFamilyOf {params : Parameters} [FieldModel params.q] {ι : Type u_1} [Fintype ι] [DecidableEq ι] (axisParallelMeasurement : AxisParallelLine paramsProjMeas (AxisLinePolynomial params) ι) :
                                          IdxSubMeas (AxisParallelTestSample params) (Fq params) ι

                                          Sampled line answers in the axis-parallel lines test, obtained from an axis-parallel measurement and evaluated at the base point.

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                                            noncomputable abbrev MIPStarRE.LDT.diagonalPointAnswerFamilyOf {params : Parameters} [FieldModel params.q] {ι : Type u_1} [Fintype ι] [DecidableEq ι] (pointMeasurement : IdxProjMeas (Point params) (Fq params) ι) (j : Fin params.m) :
                                            IdxSubMeas (RestrictedDiagonalSample params j) (Fq params) ι

                                            Sampled point answers in the restricted diagonal test, obtained from a point measurement.

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                                              noncomputable abbrev MIPStarRE.LDT.diagonalLineAnswerFamilyOf {params : Parameters} [FieldModel params.q] {ι : Type u_1} [Fintype ι] [DecidableEq ι] {Answer : Type u_2} [Fintype Answer] (diagonalMeasurement : DiagonalLine paramsProjMeas Answer ι) (evalAtBase : AnswerFq params) (j : Fin params.m) :
                                              IdxSubMeas (RestrictedDiagonalSample params j) (Fq params) ι

                                              Sampled diagonal-line answers in the restricted diagonal test, obtained from a diagonal-line measurement and evaluated at the base point.

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                                                noncomputable def MIPStarRE.LDT.axisParallelPointAnswerFamily {params : Parameters} [FieldModel params.q] {ι : Type u_1} [Fintype ι] [DecidableEq ι] (strategy : SymStrat params ι) :
                                                IdxSubMeas (AxisParallelTestSample params) (Fq params) ι

                                                Sampled point answers in the axis-parallel lines test. The point player receives u (the base point) and answers with their measurement at u.

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                                                  noncomputable def MIPStarRE.LDT.axisParallelLineAnswerFamily {params : Parameters} [FieldModel params.q] {ι : Type u_1} [Fintype ι] [DecidableEq ι] (strategy : SymStrat params ι) :
                                                  IdxSubMeas (AxisParallelTestSample params) (Fq params) ι

                                                  Sampled line answers in the axis-parallel lines test, evaluated at the base point u. The line player receives and returns a polynomial f. The verifier checks f(u) = a; since u = ℓ.pointAt zeroCoord, we evaluate f at zeroCoord.

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                                                    The axis-parallel line in F_q^(m+1) through (u, 0) in the last coordinate direction. This is the geometric line denoted B^u in the paper's last-direction notation.

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                                                      noncomputable def MIPStarRE.LDT.lastDirectionMeasurementFamily {params : Parameters} [FieldModel params.q] {ι : Type u_1} [Fintype ι] [DecidableEq ι] (strategy : SymStrat params.next ι) :

                                                      The axis-parallel line measurement family restricted to the paper's last-direction notation u ↦ B^u.

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                                                        noncomputable def MIPStarRE.LDT.diagonalPointAnswerFamily {params : Parameters} [FieldModel params.q] {ι : Type u_1} [Fintype ι] [DecidableEq ι] (strategy : SymStrat params ι) (j : Fin params.m) :
                                                        IdxSubMeas (RestrictedDiagonalSample params j) (Fq params) ι

                                                        Sampled point answers in the j-restricted diagonal test. The point player receives u and answers at u.

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                                                          noncomputable def MIPStarRE.LDT.diagonalLineAnswerFamily {params : Parameters} [FieldModel params.q] {ι : Type u_1} [Fintype ι] [DecidableEq ι] (strategy : SymStrat params ι) (j : Fin params.m) :
                                                          IdxSubMeas (RestrictedDiagonalSample params j) (Fq params) ι

                                                          Sampled diagonal-line answers in the j-restricted diagonal test, evaluated at the base point u. Since u = ℓ.pointAt zeroCoord, we evaluate f at zeroCoord.

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                                                            noncomputable def MIPStarRE.LDT.AnswerSymStrat.axisParallelPointAnswerFamily {params : Parameters} [FieldModel params.q] {ι : Type u_1} [Fintype ι] [DecidableEq ι] (strategy : AnswerSymStrat params ι) :
                                                            IdxSubMeas (AxisParallelTestSample params) (Fq params) ι

                                                            Sampled point answers in the axis-parallel lines test for an answer-valued symmetric strategy.

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                                                              noncomputable def MIPStarRE.LDT.AnswerSymStrat.axisParallelLineAnswerFamily {params : Parameters} [FieldModel params.q] {ι : Type u_1} [Fintype ι] [DecidableEq ι] (strategy : AnswerSymStrat params ι) :
                                                              IdxSubMeas (AxisParallelTestSample params) (Fq params) ι

                                                              Sampled line answers in the axis-parallel lines test for an answer-valued symmetric strategy, evaluated at the base point.

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                                                                noncomputable def MIPStarRE.LDT.AnswerSymStrat.diagonalPointAnswerFamily {params : Parameters} [FieldModel params.q] {ι : Type u_1} [Fintype ι] [DecidableEq ι] (strategy : AnswerSymStrat params ι) (j : Fin params.m) :
                                                                IdxSubMeas (RestrictedDiagonalSample params j) (Fq params) ι

                                                                Sampled point answers in the restricted diagonal test for an answer-valued symmetric strategy.

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                                                                  noncomputable def MIPStarRE.LDT.AnswerSymStrat.diagonalLineAnswerFamily {params : Parameters} [FieldModel params.q] {ι : Type u_1} [Fintype ι] [DecidableEq ι] (strategy : AnswerSymStrat params ι) (j : Fin params.m) :
                                                                  IdxSubMeas (RestrictedDiagonalSample params j) (Fq params) ι

                                                                  Sampled diagonal-line answers in the restricted diagonal test for an answer-valued symmetric strategy, evaluated at the base point.

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                                                                    noncomputable def MIPStarRE.LDT.AnswerSymStrat.axisParallelFailureProbability {params : Parameters} [FieldModel params.q] {ι : Type u_1} [Fintype ι] [DecidableEq ι] (strategy : AnswerSymStrat params ι) :

                                                                    Axis-parallel failure surrogate for an answer-valued symmetric strategy.

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                                                                      noncomputable def MIPStarRE.LDT.AnswerSymStrat.selfConsistencyFailureProbability {params : Parameters} [FieldModel params.q] {ι : Type u_1} [Fintype ι] [DecidableEq ι] (strategy : AnswerSymStrat params ι) :

                                                                      Self-consistency failure surrogate for an answer-valued symmetric strategy.

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                                                                        noncomputable def MIPStarRE.LDT.AnswerSymStrat.diagonalFailureProbability {params : Parameters} [FieldModel params.q] {ι : Type u_1} [Fintype ι] [DecidableEq ι] (strategy : AnswerSymStrat params ι) :

                                                                        Diagonal-line failure surrogate for an answer-valued symmetric strategy.

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                                                                          structure MIPStarRE.LDT.AnswerSymStrat.IsGood {params : Parameters} {ι : Type u_1} [Fintype ι] [DecidableEq ι] [FieldModel params.q] (strategy : AnswerSymStrat params ι) (eps delta gamma : Error) :

                                                                          Goodness data for an answer-valued symmetric strategy.

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                                                                            structure MIPStarRE.LDT.ProjStrat (params : Parameters) [FieldModel params.q] (ιA : Type u_1) [Fintype ιA] [DecidableEq ιA] (ιB : Type u_2) [Fintype ιB] [DecidableEq ιB] :
                                                                            Type (max (max u_1 u_2) u_3)

                                                                            Paper-faithful two-space projective strategy data.

                                                                            This matches the paper's def:general-projective-strategy (test_definition.tex, lines 98--115): Alice's and Bob's measurements act on separate local carriers ιA and ιB, and the bipartite state lives on ιA × ιB without a built-in swap symmetry.

                                                                            The isNormalized field records that the bipartite state's density operator has normalized trace 1.

                                                                            The four covariance conditions express that the line-indexed projectors descend from chosen affine parametrizations to geometric lines; transport and zero-coordinate evaluation are equivalent consequences.

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