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LeanPool.CaffarelliKohnNirenberg.Foundation.Measure.Fatou

Passing nonnegative integral bounds to an almost-everywhere limit #

theorem CKN.integral_le_of_ae_tendsto_nonneg {α : Type u_1} [MeasurableSpace α] {μ : MeasureTheory.Measure α} {f : ℕ → α → ℝ} {g : α → ℝ} {bounds : ℕ → ℝ} {bound : ℝ} (hf : ∀ (n : ℕ), MeasureTheory.Integrable (f n) μ) (hfn : ∀ (n : ℕ), 0 ≤ᵐ[μ] f n) (hg : 0 ≤ᵐ[μ] g) (hlimit : ∀ᵐ (x : α) ∂μ, Filter.Tendsto (fun (n : ℕ) => f n x) Filter.atTop (nhds (g x))) (hbound : 0 ≤ bound) (hboundLimit : Filter.Tendsto bounds Filter.atTop (nhds bound)) (hupper : ∀ (n : ℕ), ∫ (x : α), f n x ∂μ ≤ bounds n) :
∫ (x : α), g x ∂μ ≤ bound

Fatou's lemma transfers convergent upper bounds on nonnegative integrals.