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teorth/PFR
Source indexedlemma · leanprover/lean4:v4.33.0-rc1

multiTau_min_sum_le

PFR.MultiTauFunctional · PFR/MultiTauFunctional.lean:162 to 196

Source documentation

If (Xi)1im(X_i)_{1 \leq i \leq m} is a τ\tau-minimizer, then i=1md[Xi;X0]2mηd[X0;X0]\sum_{i=1}^m d[X_i; X^0] \leq \frac{2m}{\eta} d[X^0; X^0].

Exact Lean statement

lemma multiTau_min_sum_le {G Ω₀ : Type u} [hG : MeasurableFinGroup G] [hΩ₀ : MeasureSpace Ω₀]
    (p : multiRefPackage G Ω₀) (Ω : Fin p.m → Type u) (hΩ : ∀ i, MeasureSpace (Ω i))
    (hprobΩ : ∀ i, IsProbabilityMeasure (ℙ : Measure (Ω i))) (X : ∀ i, Ω i → G)
    (hX : ∀ i, Measurable (X i)) (h_min : multiTauMinimizes p Ω hΩ X) :
  ∑ i, d[X i # p.X₀] ≤ 2 * p.m * p.η⁻¹ * d[p.X₀ # p.X₀]

Complete declaration

Lean source

Canonical source
Full Lean sourceLean 4
lemma multiTau_min_sum_le {G Ω₀ : Type u} [hG : MeasurableFinGroup G] [hΩ₀ : MeasureSpace Ω₀]    (p : multiRefPackage G Ω₀) (Ω : Fin p.m  Type u) (hΩ :  i, MeasureSpace (Ω i))    (hprobΩ :  i, IsProbabilityMeasure (ℙ : Measure (Ω i))) (X :  i, Ω i  G)    (hX :  i, Measurable (X i)) (h_min : multiTauMinimizes p Ω hΩ X) :  ∑ i, d[X i # p.X₀]  2 * p.m * p.η⁻¹ * d[p.X₀ # p.X₀] := by  have hη : p.η > 0 := p.hη  have hm : p.m > 0 := by linarith [p.hm]  have hprob := p.hprob  calc    _ = p.η⁻¹ * (0 + p.η * ∑ i, d[X i # p.X₀]) := by simp; field_simp    _  p.η⁻¹ * (D[X ; hΩ] + p.η * ∑ i, d[X i # p.X₀]) := by      gcongr      exact multiDist_nonneg hΩ hprobΩ X hX    _  p.η⁻¹ * (D[fun _  p.X₀ ; fun _  hΩ₀] + p.η * (p.m * d[p.X₀ # p.X₀])) := by      apply mul_le_mul_of_nonneg_left      · have ineq := h_min (fun _  Ω₀) (fun _  hΩ₀) (fun _  hprob) (fun _  p.X₀)          (fun _  p.hmeas)        simp only [multiTau, Finset.sum_const, Finset.card_univ, Fintype.card_fin,          nsmul_eq_mul] at ineq        exact ineq      exact inv_nonneg_of_nonneg (le_of_lt hη)    _  p.η⁻¹ * (p.m * d[p.X₀ # p.X₀] + 1 * (p.m * d[p.X₀ # p.X₀])) := by      gcongr      · have : NeZero p.m := hm.ne'        apply multidist_ruzsa_III p.hm (fun _  hΩ₀) (fun _  p.X₀) _ (fun _  p.hmeas)          (fun _  p.hprob) _ 0        · intro _ _          simpa using .refl p.hmeas.aemeasurable        intro _; infer_instance      · have : 0  d[p.X₀ # p.X₀] := rdist_nonneg p.hmeas p.hmeas        positivity      exact p.hη'    _ = _ := by      field_simp      ring