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.
Internal interface connecting the split non-sofic proof modules.
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- SoficGroups.KunRootedIndicatorCrossing.indicatorVector f = WithLp.toLp 2 fun (x : V) => ↑(f x)
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Internal interface connecting the split non-sofic proof modules.
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- SoficGroups.KunRootedIndicatorCrossing.permutationMarkov p ξ = (↑(Fintype.card ι))⁻¹ • ∑ i : ι, (SoficGroups.KunRootedIndicatorCrossing.permutationUnitary✝ (p i)) ξ
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Internal interface connecting the split non-sofic proof modules.
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- SoficGroups.KunThomInvariantOrthogonal.kazhdanMarkovContractionFactor P S = max 0 (1 - P.kazhdanConstant ^ 2 / (4 * ↑S.card))
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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.
Internal interface connecting the split non-sofic proof modules.
- generator : ι → Equiv.Perm self.carrier
Internal interface connecting the split non-sofic proof modules.
Internal interface connecting the split non-sofic proof modules.
- evaluation : G → Equiv.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.
- out (a g : G) : (w a).length + (w g).length + (w (a * g)).length ≤ r → ∀ (x : X.carrier), (KunRootedIndicatorCrossing.indicatorVector X.indicator).ofLp x ≠ 0 → (X.evaluation (a * g)) x = (X.evaluation a * X.evaluation g) x
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Internal interface connecting the split non-sofic proof modules.
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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.
Internal interface connecting the split non-sofic proof modules.
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Every element of a group generated by a symmetric finite set is represented by a word whose letters all belong to that set.
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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- SoficGroups.KunActualSoficRootRadius.chosenCayleyRadiusBad A S w n r = SoficGroups.KunActualSoficRootRadius.chosenFiniteRootBad✝ A (fun (i : ↥S) => ↑i) w (S ^ r) n
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Internal interface connecting the split non-sofic proof modules.
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A finite-set indicator takes only the values zero and one.
Internal interface connecting the split non-sofic proof modules.
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- SoficGroups.KunDirectedIndicatorJensen.realPermutationMarkov σ f x = (∑ i : ι, f ((Equiv.symm (σ i)) x)) / ↑(Fintype.card ι)
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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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- SoficGroups.KunDiagonalGoodRootGraphLoss.goodPermutationGraph p B = {z ∈ SoficGroups.permutationGraph p | z.1 ∉ B ∧ z.2 ∉ B}
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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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- SoficGroups.MatchedComponentCompletion.subtypeBad Z E = {x : ↥Z | ↑x ∈ E}
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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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- One or more equations did not get rendered due to their size.
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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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Internal interface connecting the split non-sofic proof modules.