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Project-declaredLean 4.33.0-rc1 · mathlib@0434c033

E Lp Norm indicator tail eq set Integral of nonneg

MeasureTheory.eLpNorm_indicator_tail_eq_setIntegral_of_nonneg

Project documentation

A helper lemma for uniformIntegrable_iff_tendsto_iSup_setIntegral_of_nonneg.

Exact Lean statement

lemma eLpNorm_indicator_tail_eq_setIntegral_of_nonneg {f : Ω → ℝ}
    (hf : Integrable f μ) (hnonneg : 0 ≤ᵐ[μ] f) (c : ℝ≥0) :
    eLpNorm ({ω | c < ‖f ω‖₊}.indicator f) 1 μ =
      ENNReal.ofReal (∫ ω in {ω | c < f ω}, f ω ∂μ)

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
lemma eLpNorm_indicator_tail_eq_setIntegral_of_nonneg {f : Ω  }    (hf : Integrable f μ) (hnonneg : 0 ᵐ[μ] f) (c : 0) :    eLpNorm ({ω | c < ‖f ω‖₊}.indicator f) 1 μ =      ENNReal.ofReal (∫ ω in {ω | c < f ω}, f ω ∂μ) := by  rw [eLpNorm_indicator_tail_eq_setIntegral_norm hf]  apply congrArg  calc  _ = ∫ (ω : Ω) in {ω | c < f ω}, ‖f ω‖ ∂μ := by    apply setIntegral_congr_set    filter_upwards [hnonneg] with ω hω    simp [Set.ofPred, abs_of_nonneg hω]  _ = _ := by    refine setIntegral_congr_fun₀      (aestronglyMeasurable_const.nullMeasurableSet_lt hf.aestronglyMeasurable) fun ω hω => ?_    exact Real.norm_of_nonneg (c.2.trans hω.le)
Project
Brownian motion
License
Apache-2.0
Commit
5077304f5e73
Source
BrownianMotion/StochasticIntegral/UniformIntegrable.lean:99-113

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Related declarations

Project-declaredLean 4.33.0-rc1

Continuous Within At Iio indicator Ioc

continuousWithinAt_Iio_indicator_Ioc

Plain-language statement

The indicator of a half-open interval Ioc a b with constant value c is left-continuous: when approached from the left it is eventually constant, so it is continuous within Iio t at t for every t.

probabilitystochastic processesmeasure theory

Source project: Brownian motion

Person-level attribution pending.

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Project-declaredLean 4.33.0-rc1

Dense comap val nhds Within Ioi ne Bot

Dense.comap_val_nhdsWithin_Ioi_neBot

Project documentation

This is an auxillary lemma used to prove Dense.monotone_of_isRightContinuous. It is saying that if D is a dense set and a, b are two points such that a < b, then the comap of 𝓝[Set.Ioi a] a under the inclusion D → α is nontrivial. Note that a < b is necessary as this is clearly not true if a is a top element.

probabilitystochastic processesmeasure theory

Source project: Brownian motion

Person-level attribution pending.

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