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Project-declaredLean 4.33.0-rc1 · mathlib@0434c033

Is Stable has Integrable Sup

ProbabilityTheory.isStable_hasIntegrableSup

Plain-language statement

The class of processes with integrable supremum is stable.

Exact Lean statement

lemma isStable_hasIntegrableSup [SecondCountableTopology ι] :
    IsStable 𝓕 (HasIntegrableSup (E := E) · P)

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
lemma isStable_hasIntegrableSup [SecondCountableTopology ι] :    IsStable 𝓕 (HasIntegrableSup (E := E) · P) := by  refine fun X hX τ hτ  isStable_hasStronglyMeasurableSupProcess X hX.1 τ hτ, ?_  refine fun t  (isStable_hasStronglyMeasurableSupProcess X hX.1 τ hτ).comp_measurable      (measurable_const.prodMk measurable_id) |>.aestronglyMeasurable, ?_  have h_bound := (hX.2 t).hasFiniteIntegral  simp_rw [hasFiniteIntegral_def, enorm_eq_self] at h_bound   refine lt_of_le_of_lt (lintegral_mono fun ω  ?_) h_bound  apply iSup₂_le  intro s hs  simp only [stoppedProcess, Set.indicator_apply, Set.mem_ofPred_eq]  split_ifs with h_bot  · refine le_iSup₂_of_le (min ↑s (τ ω)).untopA ?_ le_rfl    · rw [WithTop.untopA_le_iff]      · exact le_trans (min_le_left _ _) (WithTop.coe_le_coe.mpr hs)      · exact ne_top_of_le_ne_top WithTop.coe_ne_top (min_le_left _ _)  · simp
Project
Brownian motion
License
Apache-2.0
Commit
5077304f5e73
Source
BrownianMotion/StochasticIntegral/ClassD.lean:479-495

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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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