Documentation

LeanPool.NonSoficGroup.Spectral

Spectral and finite-model estimates for the non-sofic group construction #

This file develops the Hilbert-space, expansion, partition, and completion estimates used in the final obstruction.

theorem SoficGroups.three_pair_sum_norm_sq {H : Type u_1} [NormedAddCommGroup H] [InnerProductSpace H] (a b c : H) :
a + b ^ 2 + b + c ^ 2 + c + a ^ 2 = a + b + c ^ 2 + (a ^ 2 + b ^ 2 + c ^ 2)

A three-vector polarization identity used in the spectral-gap argument.

theorem SoficGroups.KunThomFiberCoarea.card_entering_eq_card_exiting {V : Type u_1} [Fintype V] [DecidableEq V] (p : Equiv.Perm V) (A : Finset V) :
{x : V | xA p x A}.card = {xA | p xA}.card
theorem SoficGroups.KunThomFiberCoarea.hasAlmostCentralizerImprovement_of_rooted_reference_cuts {V : Type u_1} {ι : Type u_2} [Fintype V] [Fintype ι] [DecidableEq V] (σ : ιEquiv.Perm V) (tolerance : ) (h : ) (hpositive : 0 < h) (hexp : ∀ (A : Finset V), h * min (↑A.card) ((Fintype.card V) - A.card) (boundary σ A)) (hcut : ∀ (p : Equiv.Perm V), permutationCommutationDefect σ p 2 * tolerance∃ (U : Finset (V × V)), 2 * ((U \ permutationGraph p).card + (permutationGraph p \ U).card) Fintype.card V (h + 8 * (Fintype.card ι)) * (boundary (fun (i : ι) => Equiv.prodCongr (σ i) (σ i)) U) h * tolerance 5 * (4 * (boundary (fun (i : ι) => Equiv.prodCongr (σ i) (σ i)) U) + h * (U \ permutationGraph p).card) h * (Fintype.card V)) :

Internal interface connecting the split non-sofic proof modules.

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    noncomputable def SoficGroups.KunRootedIndicatorCrossing.permutationMarkov {ι : Type u_1} {V : Type u_2} [Fintype ι] [Fintype V] (p : ιEquiv.Perm V) (ξ : EuclideanSpace V) :

    Internal interface connecting the split non-sofic proof modules.

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      Internal interface connecting the split non-sofic proof modules.

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        Internal interface connecting the split non-sofic proof modules.

        • carrier : Type u

          Internal interface connecting the split non-sofic proof modules.

        • fintype : Fintype self.carrier

          Internal interface connecting the split non-sofic proof modules.

        • generator : ιEquiv.Perm self.carrier

          Internal interface connecting the split non-sofic proof modules.

        • indicator : self.carrier

          Internal interface connecting the split non-sofic proof modules.

        • evaluation : GEquiv.Perm self.carrier

          Internal interface connecting the split non-sofic proof modules.

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          Internal interface connecting the split non-sofic proof modules.

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            Internal interface connecting the split non-sofic proof modules.

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              theorem SoficGroups.KunActualSoficRootRadius.finiteRootBad_multiplicative {G : Type u_1} [Group G] (M : PermutationModel G) (F : Finset G) {g h : G} (hg : g F) (hh : h F) {x : Fin M.size} (hx : xfiniteRootBad M F) :
              (M.action (g * h)) x = (M.action g * M.action h) x
              theorem SoficGroups.KunActualSoficRootRadius.finiteRootBad_separated {G : Type u_1} [Group G] (M : PermutationModel G) (F : Finset G) {g h : G} (hg : g F) (hh : h F) (hne : g h) {x : Fin M.size} (hx : xfiniteRootBad M F) :
              (M.action g) x (M.action h) x
              theorem SoficGroups.KunActualSoficRootRadius.approximate_action_list_prod_tendsto {G : Type u_1} [Monoid G] (V : Type u_2) [(n : ) → Fintype (V n)] [(n : ) → DecidableEq (V n)] (p : (n : ) → GEquiv.Perm (V n)) (hone : ∀ (n : ), p n 1 = 1) (hmul : ∀ (a g : G), Filter.Tendsto (fun (n : ) => normalizedHamming (p n (a * g)) (p n a * p n g)) Filter.atTop (nhds 0)) (l : List G) :
              Filter.Tendsto (fun (n : ) => normalizedHamming (p n l.prod) (List.map (p n) l).prod) Filter.atTop (nhds 0)

              Approximate multiplicativity of unital monoid maps into permutation groups extends to each fixed finite word. The maps need not preserve multiplication exactly.

              In a sofic approximation, evaluating a fixed product agrees asymptotically with multiplying the individual permutation images.

              def SoficGroups.KunActualSoficRootRadius.chosenWordEvaluation {G : Type u_1} {ι : Type u_2} [Group G] (A : SoficApproximation G) (s : ιG) (w : GList ι) (n : ) (g : G) :

              Internal interface connecting the split non-sofic proof modules.

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                theorem SoficGroups.KunActualSoficRootRadius.exists_generator_word_of_symmetric_generates {G : Type u_1} [Group G] (S : Finset G) (hsymmetric : gS, g⁻¹ S) (hgenerates : Subgroup.closure S = ) (g : G) :
                ∃ (l : List S), (List.map (fun (i : S) => i) l).prod = g

                Every element of a group generated by a symmetric finite set is represented by a word whose letters all belong to that set.

                noncomputable def SoficGroups.KunActualSoficRootRadius.symmetricGeneratorWord {G : Type u_1} [Group G] [DecidableEq G] (S : Finset G) (hsymmetric : gS, g⁻¹ S) (hgenerates : Subgroup.closure S = ) (g : G) :
                List S

                Internal interface connecting the split non-sofic proof modules.

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                  theorem SoficGroups.KunActualSoficRootRadius.symmetricGeneratorWord_prod {G : Type u_1} [Group G] [DecidableEq G] (S : Finset G) (hsymmetric : gS, g⁻¹ S) (hgenerates : Subgroup.closure S = ) (g : G) :
                  (List.map (fun (i : S) => i) (symmetricGeneratorWord S hsymmetric hgenerates g)).prod = g
                  @[simp]
                  theorem SoficGroups.KunActualSoficRootRadius.symmetricGeneratorWord_one {G : Type u_1} [Group G] [DecidableEq G] (S : Finset G) (hsymmetric : gS, g⁻¹ S) (hgenerates : Subgroup.closure S = ) :
                  symmetricGeneratorWord S hsymmetric hgenerates 1 = []
                  theorem SoficGroups.KunActualSoficRootRadius.symmetricGeneratorWord_generator {G : Type u_1} [Group G] [DecidableEq G] (S : Finset G) (hsymmetric : gS, g⁻¹ S) (hgenerates : Subgroup.closure S = ) (i : S) (hi : i 1) :
                  symmetricGeneratorWord S hsymmetric hgenerates i = [i]
                  theorem SoficGroups.KunActualSoficRootRadius.chosen_symmetric_wordEvaluation_one {G : Type u_1} [Group G] [DecidableEq G] (A : SoficApproximation G) (S : Finset G) (hsymmetric : gS, g⁻¹ S) (hgenerates : Subgroup.closure S = ) (n : ) :
                  chosenWordEvaluation A (fun (i : S) => i) (symmetricGeneratorWord S hsymmetric hgenerates) n 1 = 1
                  theorem SoficGroups.KunActualSoficRootRadius.chosen_symmetric_wordEvaluation_generator {G : Type u_1} [Group G] [DecidableEq G] (A : SoficApproximation G) (S : Finset G) (hsymmetric : gS, g⁻¹ S) (hgenerates : Subgroup.closure S = ) (n : ) (i : S) :
                  chosenWordEvaluation A (fun (j : S) => j) (symmetricGeneratorWord S hsymmetric hgenerates) n i = (A.model n).action i
                  theorem SoficGroups.KunActualSoficRootRadius.mem_generator_pow_of_chosen_word_length {G : Type u_1} [Group G] [DecidableEq G] (S : Finset G) (hone : 1 S) (w : GList S) (hw : ∀ (g : G), (List.map (fun (i : S) => i) (w g)).prod = g) {g : G} {r : } (hgr : (w g).length r) :
                  g S ^ r
                  noncomputable def SoficGroups.KunActualSoficRootRadius.chosenCayleyRadiusBad {G : Type u_1} [Group G] [DecidableEq G] (A : SoficApproximation G) (S : Finset G) (w : GList S) (n r : ) :

                  Internal interface connecting the split non-sofic proof modules.

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                    theorem SoficGroups.KunActualSoficRootRadius.chosenCayleyRadiusBad_density_tendsto_zero {G : Type u_1} [Group G] [DecidableEq G] (A : SoficApproximation G) (S : Finset G) (w : GList S) (hw : ∀ (g : G), (List.map (fun (i : S) => i) (w g)).prod = g) (r : ) :
                    Filter.Tendsto (fun (n : ) => (chosenCayleyRadiusBad A S w n r).card / (A.model n).size) Filter.atTop (nhds 0)
                    theorem SoficGroups.KunActualSoficRootRadius.chosenCayleyRadiusBad_rooted {G : Type u_1} [Group G] [DecidableEq G] (A : SoficApproximation G) (S : Finset G) (hone : 1 S) (w : GList S) (hw : ∀ (g : G), (List.map (fun (i : S) => i) (w g)).prod = g) (n r : ) (a g : G) (hword : (w a).length + (w g).length + (w (a * g)).length r) {x : Fin (A.model n).size} (hx : xchosenCayleyRadiusBad A S w n r) :
                    (chosenWordEvaluation A (fun (i : S) => i) w n (a * g)) x = (chosenWordEvaluation A (fun (i : S) => i) w n a * chosenWordEvaluation A (fun (i : S) => i) w n g) x
                    theorem SoficGroups.KunActualSoficRootRadius.chosenCayleyRadiusBad_injective_ball {G : Type u_1} [Group G] [DecidableEq G] (A : SoficApproximation G) (S : Finset G) (w : GList S) (n r : ) {x : Fin (A.model n).size} (hx : xchosenCayleyRadiusBad A S w n r) :
                    Set.InjOn (fun (g : G) => ((A.model n).action g) x) ↑(S ^ r)

                    Internal interface connecting the split non-sofic proof modules.

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                      A finite-set indicator takes only the values zero and one.

                      noncomputable def SoficGroups.KunDirectedIndicatorJensen.realPermutationMarkov {V : Type u_1} {ι : Type u_2} [Fintype ι] (σ : ιEquiv.Perm V) (f : V) (x : V) :

                      Internal interface connecting the split non-sofic proof modules.

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                        @[reducible, inline]
                        noncomputable abbrev SoficGroups.KunFinitePermutationMarkovMass.realPermutationMarkov {V : Type u_1} {ι : Type u_2} [Fintype ι] (σ : ιEquiv.Perm V) (f : V) (x : V) :

                        Internal interface connecting the split non-sofic proof modules.

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                          theorem SoficGroups.KunResidualExpanderDecomposition.exists_expanding_full_finpartition_sequence (ι : Type u_1) [Fintype ι] (V : Type u_2) [(n : ) → Fintype (V n)] [∀ (n : ), Nonempty (V n)] [(n : ) → DecidableEq (V n)] (σ : (n : ) → ιEquiv.Perm (V n)) (B : (n : ) → Finset (V n)) (γ : ) ( : 0 < γ) (α : ) ( : ∀ (n : ), 0 α n) (hαzero : Filter.Tendsto α Filter.atTop (nhds 0)) (hbad : Filter.Tendsto (fun (n : ) => (B n).card / (Fintype.card (V n))) Filter.atTop (nhds 0)) (himprove : ∀ (n : ), TFinset.univ \ B n, (boundary (σ n) T) < γ * T.card∃ (U : Finset (V n)), 3 * (symmDiff U T).card < T.card (boundary (σ n) U) α n * U.card) :
                          ∃ (P : (n : ) → Finpartition Finset.univ), 0 < γ (∀ (n : ), C(P n).parts, EC, 2 * E.card C.cardγ * E.card (boundary (σ n) E)) Filter.Tendsto (fun (n : ) => (∑ C(P n).parts, (boundary (σ n) C)) / (Fintype.card (V n))) Filter.atTop (nhds 0)
                          theorem SoficGroups.KunResidualExpanderDecomposition.original_boundary_le_completed_add_component_boundary {V : Type u_1} {ι : Type u_2} [Fintype ι] [DecidableEq V] (σ : ιEquiv.Perm V) (C : Finset V) (τ : ιEquiv.Perm C) ( : ∀ (i : ι) (x : V) (hx : x C), (σ i) x C((τ i) x, hx) = (σ i) x) (A : Finset C) :
                          boundary σ (Finset.map (Function.Embedding.subtype fun (x : V) => x C) A) boundary τ A + boundary σ C
                          theorem SoficGroups.KunResidualExpanderDecomposition.completed_component_additive_expansion {V : Type u_1} {ι : Type u_2} [Fintype ι] [DecidableEq V] (σ : ιEquiv.Perm V) (C : Finset V) (τ : ιEquiv.Perm C) ( : ∀ (i : ι) (x : V) (hx : x C), (σ i) x C((τ i) x, hx) = (σ i) x) (γ : ) (hexpand : EC, 2 * E.card C.cardγ * E.card (boundary σ E)) (A : Finset C) :
                          γ * min (↑A.card) (C.card - A.card) - (boundary σ C) (boundary τ A)

                          Internal interface connecting the split non-sofic proof modules.

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                            theorem SoficGroups.KunCompletedPrunedComponent.exists_completed_pruned_expander {V : Type u_1} {ι : Type u_2} [Fintype V] [Fintype ι] [DecidableEq V] (σ : ιEquiv.Perm V) (γ ell a : ) (hgap : ell < γ) (hadd : ∀ (A : Finset V), γ * min (↑A.card) ((Fintype.card V) - A.card) - a * (Fintype.card V) (boundary σ A)) (hsmall : 2 * a * (2 * (γ - ell) + (Fintype.card ι)) (γ - ell) ^ 2) :
                            ∃ (B : Finset V) (τ : ιEquiv.Perm ↥(Finset.univ \ B)), 2 * B.card Fintype.card V B.card a * (Fintype.card V) / (γ - ell) (∀ (i : ι) (x : V) (hx : x Finset.univ \ B), (σ i) x Finset.univ \ B((τ i) x, hx) = (σ i) x) ∀ (A : Finset ↥(Finset.univ \ B)), ell * min (↑A.card) ((Fintype.card ↥(Finset.univ \ B)) - A.card) (boundary τ A)

                            Internal interface connecting the split non-sofic proof modules.

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                              theorem SoficGroups.MatchedComponentCompletion.completedRestriction_apply_of_mem {V : Type u_1} [Fintype V] (p : Equiv.Perm V) (Z : Finset V) (x : V) (hx : x Z) (hp : p x Z) :
                              ((completedRestriction p Z) x, hx) = p x

                              Internal interface connecting the split non-sofic proof modules.

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                                theorem SoficGroups.MatchedComponentCompletion.permutationDistance_le_subtypeBad {V : Type u_1} [DecidableEq V] (Z E : Finset V) (p q : Equiv.Perm Z) (hagrees : ∀ (x : Z), xEp x = q x) :
                                noncomputable def SoficGroups.MatchedComponentCompletion.sourceCompletionBad {V : Type u_1} {ι : Type u_2} {J : Type u_3} [DecidableEq V] [Fintype ι] [Group J] (σ : ιEquiv.Perm V) (p : JEquiv.Perm V) (F : Finset J) (Z : Finset V) :

                                Internal interface connecting the split non-sofic proof modules.

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                                  theorem SoficGroups.MatchedComponentCompletion.sourceCompletionBad_subset {V : Type u_1} {ι : Type u_2} {J : Type u_3} [DecidableEq V] [Fintype ι] [Group J] (σ : ιEquiv.Perm V) (p : JEquiv.Perm V) (F : Finset J) (Z : Finset V) :
                                  sourceCompletionBad σ p F ZZ
                                  theorem SoficGroups.MatchedComponentCompletion.card_subtype_sourceCompletionBad {V : Type u_1} {ι : Type u_2} {J : Type u_3} [DecidableEq V] [Fintype ι] [Group J] (σ : ιEquiv.Perm V) (p : JEquiv.Perm V) (F : Finset J) (Z : Finset V) :
                                  theorem SoficGroups.MatchedComponentCompletion.completedRestriction_mul_of_not_mem_sourceCompletionBad {V : Type u_1} {ι : Type u_2} {J : Type u_3} [Fintype V] [DecidableEq V] [Fintype ι] [Group J] (σ : ιEquiv.Perm V) (p : JEquiv.Perm V) (F : Finset J) (Z : Finset V) {j k : J} (hj : j F) (hk : k F) (z : Z) (hz : zsourceCompletionBad σ p F Z) :
                                  theorem SoficGroups.MatchedComponentCompletion.completedRestriction_ne_of_not_mem_sourceCompletionBad {V : Type u_1} {ι : Type u_2} {J : Type u_3} [Fintype V] [DecidableEq V] [Fintype ι] [Group J] (σ : ιEquiv.Perm V) (p : JEquiv.Perm V) (F : Finset J) (Z : Finset V) {j k : J} (hj : j F) (hk : k F) (hne : j k) (z : Z) (hz : zsourceCompletionBad σ p F Z) :
                                  theorem SoficGroups.MatchedComponentCompletion.completedRestriction_commute_of_not_mem_sourceCompletionBad {V : Type u_1} {ι : Type u_2} {J : Type u_3} [Fintype V] [DecidableEq V] [Fintype ι] [Group J] (σ : ιEquiv.Perm V) (p : JEquiv.Perm V) (F : Finset J) (Z : Finset V) (σZ : ιEquiv.Perm Z) (hσZ : ∀ (i : ι) (x : V) (hx : x Z), (σ i) x Z((σZ i) x, hx) = (σ i) x) {j : J} (hj : j CompressionCriterion.productTrackedTable F) (i : ι) (z : Z) (hz : zsourceCompletionBad σ p F Z) :
                                  (completedRestriction (p j) Z) ((σZ i) z) = (σZ i) ((completedRestriction (p j) Z) z)
                                  theorem SoficGroups.MatchedComponentCompletion.completedRestriction_mul_distance_le_sourceCompletionBad {V : Type u_1} {ι : Type u_2} {J : Type u_3} [Fintype V] [DecidableEq V] [Fintype ι] [Group J] (σ : ιEquiv.Perm V) (p : JEquiv.Perm V) (F : Finset J) (Z : Finset V) {j k : J} (hj : j F) (hk : k F) :
                                  theorem SoficGroups.MatchedComponentCompletion.completedRestriction_separated_of_sourceCompletionBad {V : Type u_1} {ι : Type u_2} {J : Type u_3} [Fintype V] [DecidableEq V] [Fintype ι] [Group J] (σ : ιEquiv.Perm V) (p : JEquiv.Perm V) (F : Finset J) (Z : Finset V) (hZ : Z.Nonempty) (hbad : 5 * (sourceCompletionBad σ p F Z).card Z.card) {j k : J} (hj : j F) (hk : k F) (hne : j k) :
                                  theorem SoficGroups.MatchedComponentCompletion.completedRestriction_commutationDefect_le_sourceCompletionBad {V : Type u_1} {ι : Type u_2} {J : Type u_3} [Fintype V] [DecidableEq V] [Fintype ι] [Group J] (σ : ιEquiv.Perm V) (p : JEquiv.Perm V) (F : Finset J) (Z : Finset V) (σZ : ιEquiv.Perm Z) (hσZ : ∀ (i : ι) (x : V) (hx : x Z), (σ i) x Z((σZ i) x, hx) = (σ i) x) {j : J} (hj : j CompressionCriterion.productTrackedTable F) :
                                  noncomputable def SoficGroups.MatchedComponentExitBudget.sourceWordTestBad {V : Type u_1} {ι : Type u_2} {J : Type u_3} [Fintype V] [DecidableEq V] [Fintype ι] [Group J] (σ : ιEquiv.Perm V) (p : JEquiv.Perm V) (F : Finset J) :

                                  Internal interface connecting the split non-sofic proof modules.

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                                    theorem SoficGroups.MatchedComponentExitBudget.sourceCompletionBad_subset_exit_union_wordBad {V : Type u_1} {ι : Type u_2} {J : Type u_3} [Fintype V] [DecidableEq V] [Fintype ι] [Group J] (σ : ιEquiv.Perm V) (p : JEquiv.Perm V) (F : Finset J) (Z : Finset V) :
                                    MatchedComponentCompletion.sourceCompletionBad σ p F Z ⊆ (((Finset.univ.biUnion fun (i : ι) => {zZ | (σ i) zZ}) (CompressionCriterion.productTrackedTable F).biUnion fun (j : J) => {zZ | (p j) zZ}) Finset.univ.biUnion fun (i : ι) => (CompressionCriterion.productTrackedTable F).biUnion fun (j : J) => {zZ | (p j) ((σ i) z)Z}) sourceWordTestBad σ p F
                                    theorem SoficGroups.MatchedComponentExitBudget.sourceCompletionBad_surviving_density_tendsto_zero (V : Type u_1) [(n : ) → Fintype (V n)] [(n : ) → DecidableEq (V n)] {ι : Type u_2} {J : Type u_3} [Fintype ι] [Group J] (σ : (n : ) → ιEquiv.Perm (V n)) (p : (n : ) → JEquiv.Perm (V n)) (F : Finset J) (B : (n : ) → Finset (V n)) (hZ : ∀ (n : ), (Finset.univ \ B n).Nonempty) (hdeleted : Filter.Tendsto (fun (n : ) => (B n).card / (Fintype.card (V n))) Filter.atTop (nhds 0)) (hword : Filter.Tendsto (fun (n : ) => (sourceWordTestBad (σ n) (p n) F).card / (Fintype.card (V n))) Filter.atTop (nhds 0)) :
                                    theorem SoficGroups.MatchedComponentExitBudget.pruned_component_card_tendsto_atTop (V : Type u_1) [(n : ) → Fintype (V n)] [(n : ) → DecidableEq (V n)] (B : (n : ) → Finset (V n)) (hsize : Filter.Tendsto (fun (n : ) => Fintype.card (V n)) Filter.atTop Filter.atTop) (hdeleted : Filter.Tendsto (fun (n : ) => (B n).card / (Fintype.card (V n))) Filter.atTop (nhds 0)) :
                                    @[reducible, inline]
                                    noncomputable abbrev SoficGroups.KunRealComplexMarkovBridge.realMarkov {ι : Type u_1} {V : Type u_2} [Fintype ι] (p : ιEquiv.Perm V) (f : V) (x : V) :

                                    Internal interface connecting the split non-sofic proof modules.

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                                      @[reducible, inline]

                                      Internal interface connecting the split non-sofic proof modules.

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                                        @[reducible, inline]
                                        noncomputable abbrev SoficGroups.KunRealComplexMarkovBridge.permutationMarkov {ι : Type u_1} {V : Type u_2} [Fintype ι] [Fintype V] (p : ιEquiv.Perm V) (ξ : EuclideanSpace V) :

                                        Internal interface connecting the split non-sofic proof modules.

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