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RequestProject.HadamardCn3TorusCount

Torus / Count Bridge For The Cn^3 Formalization #

This module contains the torus-coordinate model, the Fourier inversion bridge, and the normalized-count identification used throughout the formalization.

Readers primarily interested in the combinatorial-to-analytic translation should start with:

def Cn3Torus.d (n : ) :

Edge-coordinate dimension.

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    Strict upper-triangular coordinates, viewed as edges of K_n.

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      noncomputable def Cn3Torus.edgeToSym2Subtype {n : } (e : Edge n) :
      { a : Sym2 (Fin n) // ¬a.IsDiag }

      Identify an edge with the corresponding non-diagonal unordered pair.

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        The edge-coordinate space has dimension n.choose 2.

        Boolean spin encoding, matching the edge-model torus setup.

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          def Cn3Torus.Z {n : } (y : Fin nBool) :
          Edge n

          Edge monomials attached to a Boolean sign vector.

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            def Cn3Torus.phase {n : } (lam : Edge n) (y : Fin nBool) :

            The edge-model phase.

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              def Cn3Torus.psi (n : ) (lam : Edge n) :

              Edge-model characteristic function.

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                def Cn3Torus.sqNormEdge (n : ) (lam : Edge n) :

                Edge-model squared norm.

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                  def Cn3Torus.torusBox (n : ) :
                  Set (Edge n)

                  The torus fundamental box of side length in edge coordinates.

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                    Complex torus integral before taking real parts.

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                      Real quarter-scale torus integral.

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                        Torus integral normalized by the torus volume (2π)^d.

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                          Edge-count as a real number.

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                            Fixed local radius used in the torus decomposition package.

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                              def Cn3Torus.localBox (n : ) :
                              Set (Edge n)

                              Local box around a lattice point in edge coordinates.

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                                theorem Cn3Torus.sqNormEdge_coord_sq_le (n : ) (lam : Edge n) (e : Edge n) :
                                lam e ^ 2 sqNormEdge n lam

                                A single coordinate square is bounded by the total edge squared norm.

                                Local integral over the core box.

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                                  The tex prefactor converting local integrals to normalized torus scale.

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                                    theorem Cn3Torus.n_le_two_mul_d (n : ) (hn : 3 n) :
                                    n 2 * d n
                                    theorem Cn3Torus.lem_fourier_inversion_all (n m : ) :
                                    (torusIntegralC n m).re = (lam : Edge n) in torusBox n, (psi n lam ^ m).re

                                    Fourier inversion on the quarter-scale torus model.

                                    This identifies the real-valued target integral used in the paper with the real part of the complex torus integral torusIntegralC.

                                    @[reducible, inline]
                                    abbrev Cn3Torus.EdgeNe {n : } (e0 : Edge n) :
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                                      theorem Cn3Torus.pow_nat_le_nat_pow_mul_exp {u : } (m : ) (hm : 0 < m) (hu : 0 u) :
                                      u ^ m m ^ m * Real.exp u

                                      A coarse but convenient domination of polynomial growth by a single exponential.

                                      theorem Cn3Torus.log_nat_lt_half (n : ) (hn : 3 n) :
                                      Real.log n < n / 2
                                      def Cn3Torus.avgOver (n : ) (f : (Fin nBool)) :

                                      Averaging over all Boolean sign vectors.

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                                        theorem Cn3Torus.avgOver_const (n : ) (c : ) :
                                        (avgOver n fun (x : Fin nBool) => c) = c
                                        def Cn3Torus.W {n : } (mu : Edge n) (y : Fin nBool) :

                                        The edge-model polynomial W, equal to phase.

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                                          theorem Cn3Torus.phase_eq_W {n : } (mu : Edge n) (y : Fin nBool) :
                                          phase mu y = W mu y
                                          def Cn3Torus.edgesIncident (n : ) (i : Fin n) :

                                          The edges incident to a given vertex.

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                                            theorem Cn3Torus.mem_edgesIncident_iff {n : } {i : Fin n} {e : Edge n} :
                                            e edgesIncident n i (↑e).1 = i (↑e).2 = i
                                            def Cn3Torus.flipBoolAt {n : } (i : Fin n) (y : Fin nBool) :
                                            Fin nBool

                                            Flip the Boolean sign at a single vertex.

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                                              theorem Cn3Torus.Z_sq_eq_one {n : } (y : Fin nBool) (e : Edge n) :
                                              Z y e ^ 2 = 1
                                              theorem Cn3Torus.Z_flip_at {n : } (i : Fin n) (y : Fin nBool) (e : Edge n) :
                                              Z (flipBoolAt i y) e = if e edgesIncident n i then -Z y e else Z y e
                                              theorem Cn3Torus.sum_flipBoolAt_eq {n : } {β : Type u_1} [AddCommMonoid β] (i : Fin n) (f : (Fin nBool)β) :
                                              y : Fin nBool, f (flipBoolAt i y) = y : Fin nBool, f y
                                              def Cn3Torus.edgeNatRowSum {n : } (b : Edge n) (i : Fin n) :

                                              Row-degree of an edge monomial at vertex i.

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                                                def Cn3Torus.edgeZMonomial {n : } (b : Edge n) (y : Fin nBool) :

                                                Edge monomial in the sign variables.

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                                                  theorem Cn3Torus.avg_edgeZMonomial_eq_ite_allEven {n : } (b : Edge n) :
                                                  (avgOver n fun (y : Fin nBool) => edgeZMonomial b y) = if ∀ (i : Fin n), Even (edgeNatRowSum b i) then 1 else 0
                                                  def Cn3Torus.edgeMultiplicity4 {n : } (e₁ e₂ e₃ e₄ : Edge n) :
                                                  Edge n

                                                  Edge multiplicities attached to an ordered 4-tuple of edges.

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                                                    theorem Cn3Torus.edgeZMonomial_add {n : } (b₁ b₂ : Edge n) (y : Fin nBool) :
                                                    edgeZMonomial (fun (e : Edge n) => b₁ e + b₂ e) y = edgeZMonomial b₁ y * edgeZMonomial b₂ y
                                                    theorem Cn3Torus.edgeZMonomial_single {n : } (y : Fin nBool) (e₀ : Edge n) :
                                                    edgeZMonomial (fun (e : Edge n) => if e = e₀ then 1 else 0) y = Z y e₀
                                                    theorem Cn3Torus.edgeZMonomial_edgeMultiplicity4 {n : } (y : Fin nBool) (e₁ e₂ e₃ e₄ : Edge n) :
                                                    edgeZMonomial (edgeMultiplicity4 e₁ e₂ e₃ e₄) y = Z y e₁ * Z y e₂ * Z y e₃ * Z y e₄
                                                    theorem Cn3Torus.exists_incident_xor_of_ne {n : } {e f : Edge n} (hef : e f) :
                                                    ∃ (i : Fin n), e edgesIncident n i fedgesIncident n i f edgesIncident n i eedgesIncident n i
                                                    theorem Cn3Torus.card_lambdaShifts_eq_pow_of_two_le (n : ) (hn : 2 n) :
                                                    (lambdaShifts n).card = 2 ^ (2 * d n - n + 1)

                                                    Edge Coordinate Transport #

                                                    The public transport maps edgeLam and matrixOfEdge identify matrix and edge coordinates. The Boolean-encoding conversions below are kept internal so the reader sees the transport results rather than the implementation vocabulary.

                                                    def signVecToBoolVec {n : } (σ : Fin nFin 2) :
                                                    Fin nBool

                                                    Pointwise transport of sign vectors to the Bool-valued edge model.

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                                                      def signVecEquivBoolVec (n : ) :
                                                      (Fin nFin 2) (Fin nBool)

                                                      Equivalence between the two encodings of sign vectors.

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                                                        def edgeLam (n : ) (lam : Fin nFin n) :

                                                        Read a strict upper-triangular matrix as an edge-indexed function.

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                                                          def matrixOfEdge (n : ) (mu : Cn3Torus.Edge n) :
                                                          Fin nFin n

                                                          Embed edge coordinates back into the strict upper-triangular matrix model.

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                                                            Edge-to-matrix transport is continuous coordinatewise.

                                                            theorem edgeLam_matrixOfEdge (n : ) (mu : Cn3Torus.Edge n) :
                                                            edgeLam n (matrixOfEdge n mu) = mu
                                                            theorem sNorm_eq_sqNormEdge (n : ) (lam : Fin nFin n) :
                                                            theorem innerX_eq_edgePhase (n : ) (lam : Fin nFin n) (σ : Fin nFin 2) :
                                                            theorem psi_matrixOfEdge_eq (n : ) (mu : Cn3Torus.Edge n) :

                                                            Exact count-to-integral bridge for the torus model.

                                                            The torus integral equals the torus volume times the number of n × s partial Hadamard matrices, divided by the ambient sign count 2^(ns). This is the formal Fourier-inversion step connecting the combinatorial count to the analytic integral.

                                                            def Cn3Torus.edgeFromOffdiag {n : } (i : Fin n) (j : { k : Fin n // k i }) :
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                                                              def Cn3Torus.offdiagOfIncident {n : } (i : Fin n) (e : Edge n) (he : e edgesIncident n i) :
                                                              { k : Fin n // k i }
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                                                                theorem momentX_eq_avgOver_W_pow (n : ) (lam : Fin nFin n) (k : ) :
                                                                momentX n lam k = Cn3Torus.avgOver n fun (y : Fin nBool) => Cn3Torus.W (edgeLam n lam) y ^ k
                                                                theorem avgSigns_abs_innerX_pow_eq_avgOver_abs_W_pow (n : ) (lam : Fin nFin n) (k : ) :
                                                                (avgSigns n fun (σ : Fin nFin 2) => |innerX n lam σ| ^ k) = Cn3Torus.avgOver n fun (y : Fin nBool) => |Cn3Torus.W (edgeLam n lam) y| ^ k
                                                                def box (n : ) (delta : ) :
                                                                Set (Fin nFin n)

                                                                The box B_δ = {λ : |λ_{ij}| ≤ δ for all i < j}.

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                                                                  def coreRegion (n : ) (t : ) :
                                                                  Set (Fin nFin n)

                                                                  The inner-core region D_t = {λ : s(λ) ≤ d/t}.

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                                                                    def edgeBox (n : ) (delta : ) :

                                                                    Edge-coordinate transport of the prototype box B_δ.

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                                                                      def edgeEuclidBall (n : ) (r : ) :

                                                                      Edge-coordinate transport of the Euclidean ball D_r.

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                                                                        def edgeCoreRegion (n : ) (t : ) :

                                                                        Edge-coordinate transport of the core region D_t.

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                                                                          def edgeEvenFarShell (n : ) (r : ) :

                                                                          Edge-coordinate transport of the even far shell.

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                                                                            theorem edgeBox_eq_pi (n : ) (delta : ) :
                                                                            edgeBox n delta = Set.univ.pi fun (x : Cn3Torus.Edge n) => Set.Icc (-delta) delta
                                                                            theorem edgeBox_isCompact (n : ) (delta : ) :
                                                                            IsCompact (edgeBox n delta)
                                                                            theorem edgeBox_volume_eq (n : ) (delta : ) (hdelta : 0 delta) :
                                                                            def Cn3Torus.edgeResidualTorusRegion (n : ) (delta : ) :
                                                                            Set (Edge n)

                                                                            Residual torus region left after removing all translated primary boxes.

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                                                                              theorem mem_edgeCoreRegion_iff (n : ) (t : ) (mu : Cn3Torus.Edge n) :

                                                                              Fourier Inversion and Count Bridge #

                                                                              This section packages the de Launey-Levin quarter-scale Fourier bridge in the form used by the rest of the active development.

                                                                              Fact 2.3 [DL10]: quarter-scale Fourier inversion in the edge-coordinate torus model. This is the exact bridge from the combinatorial normalized count to the normalized torus integral.

                                                                              theorem universal_magnitude_bound_full (n : ) (hn : 2 n) (gam : Fin nFin n) (k : Fin n) :
                                                                              psi n gam ^ 2 1 / 2 + 1 / 2 * i : Fin n, if i = k then 1 else if i < k then Real.cos (2 * gam i k) else Real.cos (2 * gam k i)

                                                                              Fact 3.3 [DL10]: Full magnitude bound with product.

                                                                              theorem avgSigns_mul_sq_le_avgSigns_sq_mul_avgSigns_sq (n : ) (u v : (Fin nFin 2)) :
                                                                              (avgSigns n fun (σ : Fin nFin 2) => u σ * v σ) ^ 2 (avgSigns n fun (σ : Fin nFin 2) => u σ ^ 2) * avgSigns n fun (σ : Fin nFin 2) => v σ ^ 2
                                                                              theorem fixedDegreeHC_degree2_W_sixth (n : ) (mu : Cn3Torus.Edge n) :
                                                                              (Cn3Torus.avgOver n fun (y : Fin nBool) => |Cn3Torus.W mu y| ^ 6) 5 ^ 6 * Cn3Torus.sqNormEdge n mu ^ 3

                                                                              Manuscript Fact 4.5(i): the degree-2 chaos W satisfies the L^6 hypercontractive bound with constant 5^6.

                                                                              theorem fixedDegreeHC_degree2_W_seventh_uniform (n : ) (mu : Cn3Torus.Edge n) :
                                                                              (Cn3Torus.avgOver n fun (y : Fin nBool) => |Cn3Torus.W mu y| ^ 7) 6 ^ 7 * Cn3Torus.sqNormEdge n mu ^ (7 / 2)
                                                                              theorem normalized_edgeResidualTorusRegion_abs_le_cos_pow (n t : ) (hn : 2 n) {deltaBox : } (hdelta_pos : 0 < deltaBox) (hdelta_lt : deltaBox < Real.pi / 4) :
                                                                              |1 / (2 * Real.pi) ^ Cn3Torus.d n * (lam : Cn3Torus.Edge n) in Cn3Torus.edgeResidualTorusRegion n deltaBox, (Cn3Torus.psi n lam ^ (4 * t)).re| Real.cos deltaBox ^ (4 * t)
                                                                              theorem normalizedCount_primary_secondary_decomposition (n t : ) {delta : } (hdelta_lt : delta < Real.pi / 4) :
                                                                              normalizedCount n (4 * t) = ((Cn3Torus.lambdaShifts n).card / (2 * Real.pi) ^ Cn3Torus.d n * (mu : Cn3Torus.Edge n) in edgeBox n delta, (Cn3Torus.psi n mu ^ (4 * t)).re) + 1 / (2 * Real.pi) ^ Cn3Torus.d n * (mu : Cn3Torus.Edge n) in Cn3Torus.edgeResidualTorusRegion n delta, (Cn3Torus.psi n mu ^ (4 * t)).re

                                                                              The actual primary-secondary torus decomposition from the manuscript, written in edge coordinates and normalized directly at the normalized-count scale.

                                                                              The global normalized count is within the exponentially small Rdelta error of the transported local-box contribution.