@@ -8597,6 +8597,66 @@ Proof.
85978597 reflexivity.
85988598Qed .
85998599
8600+ Lemma isfe_prod_fst {Ts} {dom : SigmaAlgebra Ts} (prts : ProbSpace dom) (f : Ts -> R)
8601+ {rv : RandomVariable dom borel_sa f}
8602+ {isfe : IsFiniteExpectation prts f} :
8603+ IsFiniteExpectation (product_ps prts prts)
8604+ (fun p : Ts * Ts => f (fst p)).
8605+ Proof .
8606+ generalize (@pullback_law (Ts * Ts) Ts (product_sa dom dom) dom
8607+ (product_ps prts prts) fst f); intros.
8608+ generalize (fst_rv (T1 := Ts * Ts) (T2 := Ts) (product_sa dom dom) dom ); intros.
8609+ specialize (H _ _).
8610+ unfold compose in H.
8611+ rewrite <- Expectation_Rbar_Expectation in H.
8612+ rewrite <- Expectation_Rbar_Expectation in H.
8613+ unfold IsFiniteExpectation.
8614+ rewrite H.
8615+ assert (Expectation
8616+ (Prts :=
8617+ (@pullback_ps (prod Ts Ts) Ts (@product_sa Ts Ts dom dom) dom
8618+ (@product_ps Ts Ts dom dom prts prts) (@fst Ts Ts)
8619+ (@fst_rv Ts Ts dom dom))) f =
8620+ Expectation (Prts := prts) f).
8621+ {
8622+ apply Expectation_ext_ps'; try easy.
8623+ intros ?.
8624+ now rewrite <- product_pullback_fst.
8625+ }
8626+ rewrite H1.
8627+ apply isfe.
8628+ Qed .
8629+
8630+ Lemma isfe_prod_snd {Ts} {dom : SigmaAlgebra Ts} (prts : ProbSpace dom) (f : Ts -> R)
8631+ {rv : RandomVariable dom borel_sa f}
8632+ {isfe : IsFiniteExpectation prts f} :
8633+ IsFiniteExpectation (product_ps prts prts)
8634+ (fun p : Ts * Ts => f (snd p)).
8635+ Proof .
8636+ generalize (@pullback_law (Ts * Ts) Ts (product_sa dom dom) dom
8637+ (product_ps prts prts) snd f); intros.
8638+ generalize (fst_rv (T1 := Ts * Ts) (T2 := Ts) (product_sa dom dom) dom ); intros.
8639+ specialize (H _ _).
8640+ unfold compose in H.
8641+ rewrite <- Expectation_Rbar_Expectation in H.
8642+ rewrite <- Expectation_Rbar_Expectation in H.
8643+ unfold IsFiniteExpectation.
8644+ rewrite H.
8645+ assert (Expectation
8646+ (Prts :=
8647+ (@pullback_ps (prod Ts Ts) Ts (@product_sa Ts Ts dom dom) dom
8648+ (@product_ps Ts Ts dom dom prts prts) (@snd Ts Ts)
8649+ (@snd_rv Ts Ts dom dom))) f =
8650+ Expectation (Prts := prts) f).
8651+ {
8652+ apply Expectation_ext_ps'; try easy.
8653+ intros ?.
8654+ now rewrite <- product_pullback_snd.
8655+ }
8656+ rewrite H1.
8657+ apply isfe.
8658+ Qed .
8659+
86008660Require Import Dynkin.
86018661Section monotone_class.
86028662
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