teorth/PFR
Source indexedlemma · leanprover/lean4:v4.33.0-rc1
ProbabilityTheory.iIndepFun.finsets_comp'
PFR.Mathlib.Probability.Independence.Basic · PFR/Mathlib/Probability/Independence/Basic.lean:108 to 131
Source documentation
A variant of iIndepFun.finsets_comp where we conclude the independence of just two functions rather than an entire family.
Exact Lean statement
lemma iIndepFun.finsets_comp' {f : ∀ i, Ω → β i} {S S' : Finset ι} (h_disjoint : Disjoint S S')
(hf_Indep : iIndepFun f μ) (hf_meas : ∀ i, Measurable (f i))
{γ γ' : Type u} {mγ : MeasurableSpace γ} {mγ' : MeasurableSpace γ'}
{φ : (∀ i : S, β i) → γ} {φ' : (∀ i : S', β i) → γ'} (hφ : Measurable φ) (hφ' : Measurable φ') :
IndepFun (fun a ↦ φ (fun (i : S) ↦ f i a)) (fun a ↦ φ' (fun (i : S') ↦ f i a)) μComplete declaration
Lean source
Full Lean sourceLean 4
lemma iIndepFun.finsets_comp' {f : ∀ i, Ω → β i} {S S' : Finset ι} (h_disjoint : Disjoint S S') (hf_Indep : iIndepFun f μ) (hf_meas : ∀ i, Measurable (f i)) {γ γ' : Type u} {mγ : MeasurableSpace γ} {mγ' : MeasurableSpace γ'} {φ : (∀ i : S, β i) → γ} {φ' : (∀ i : S', β i) → γ'} (hφ : Measurable φ) (hφ' : Measurable φ') : IndepFun (fun a ↦ φ (fun (i : S) ↦ f i a)) (fun a ↦ φ' (fun (i : S') ↦ f i a)) μ := by set S₂ := ![S,S'] set γ₂ := ![γ,γ'] set φ₂ : (j:Fin 2) → ((i: S₂ j) → β i) → γ₂ j := fun j => match j with | 0 => φ | 1 => φ' have h_disjoint₂ : Set.PairwiseDisjoint Set.univ S₂ := by simp_rw [Set.PairwiseDisjoint, Set.Pairwise, Fin.forall_fin_two, Function.onFun] simp [h_disjoint, h_disjoint.symm, S₂] set mγ₂ : (j:Fin 2) → MeasurableSpace (γ₂ j) := fun j ↦ match j with | 0 => mγ | 1 => mγ' have hφ₂ (j:Fin 2) : Measurable (φ₂ j) := match j with | 0 => hφ | 1 => hφ' have hneq : (0:Fin 2) ≠ (1:Fin 2) := by simp simpa [φ₂, γ₂] using! (iIndepFun.finsets_comp S₂ h_disjoint₂ hf_Indep hf_meas φ₂ hφ₂).indepFun hneq