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Mathlib.MeasureTheory.Integral.Lebesgue.MeasurePreserving

Behavior of the Lebesgue integral under measure-preserving maps #

theorem MeasureTheory.MeasurePreserving.lintegral_map_equiv {α : Type u_1} {β : Type u_2} [MeasurableSpace α] [MeasurableSpace β] {μ : Measure α} {ν : Measure β} (f : βENNReal) (g : α ≃ᵐ β) (hg : MeasurePreserving (⇑g) μ ν) :
∫⁻ (a : β), f a ν = ∫⁻ (a : α), f (g a) μ
theorem MeasureTheory.MeasurePreserving.lintegral_comp {α : Type u_1} {β : Type u_2} [MeasurableSpace α] [MeasurableSpace β] {μ : Measure α} {ν : Measure β} {g : αβ} (hg : MeasurePreserving g μ ν) {f : βENNReal} (hf : Measurable f) :
∫⁻ (a : α), f (g a) μ = ∫⁻ (b : β), f b ν
theorem MeasureTheory.MeasurePreserving.lintegral_comp_emb {α : Type u_1} {β : Type u_2} [MeasurableSpace α] [MeasurableSpace β] {μ : Measure α} {ν : Measure β} {g : αβ} (hg : MeasurePreserving g μ ν) (hge : MeasurableEmbedding g) (f : βENNReal) :
∫⁻ (a : α), f (g a) μ = ∫⁻ (b : β), f b ν
theorem MeasureTheory.MeasurePreserving.setLIntegral_comp_preimage {α : Type u_1} {β : Type u_2} [MeasurableSpace α] [MeasurableSpace β] {μ : Measure α} {ν : Measure β} {g : αβ} (hg : MeasurePreserving g μ ν) {s : Set β} (hs : MeasurableSet s) {f : βENNReal} (hf : Measurable f) :
∫⁻ (a : α) in g ⁻¹' s, f (g a) μ = ∫⁻ (b : β) in s, f b ν
theorem MeasureTheory.MeasurePreserving.setLIntegral_comp_preimage_emb {α : Type u_1} {β : Type u_2} [MeasurableSpace α] [MeasurableSpace β] {μ : Measure α} {ν : Measure β} {g : αβ} (hg : MeasurePreserving g μ ν) (hge : MeasurableEmbedding g) (f : βENNReal) (s : Set β) :
∫⁻ (a : α) in g ⁻¹' s, f (g a) μ = ∫⁻ (b : β) in s, f b ν
theorem MeasureTheory.MeasurePreserving.setLIntegral_comp_emb {α : Type u_1} {β : Type u_2} [MeasurableSpace α] [MeasurableSpace β] {μ : Measure α} {ν : Measure β} {g : αβ} (hg : MeasurePreserving g μ ν) (hge : MeasurableEmbedding g) (f : βENNReal) (s : Set α) :
∫⁻ (a : α) in s, f (g a) μ = ∫⁻ (b : β) in g '' s, f b ν