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minor generalization of eq_measure_integral
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affeldt-aist committed Jul 22, 2022
1 parent 3e6aacb commit 1661370
Showing 1 changed file with 4 additions and 4 deletions.
8 changes: 4 additions & 4 deletions theories/lebesgue_integral.v
Original file line number Diff line number Diff line change
Expand Up @@ -1056,7 +1056,7 @@ Variables (d : measure_display) (T : measurableType d) (R : realType)
Implicit Types m : {measure set T -> \bar R}.

Let eq_measure_integral0 m2 m1 (f : T -> \bar R) :
(forall A, A `<=` D -> m1 A = m2 A) ->
(forall A, measurable A -> A `<=` D -> m1 A = m2 A) ->
[set sintegral m1 h | h in
[set h : {nnsfun T >-> R} | (forall x, (h x)%:E <= (f \_ D) x)]] `<=`
[set sintegral m2 h | h in
Expand All @@ -1074,12 +1074,12 @@ by rewrite le_eqVlt eqe (negbTE ht0)/= lte_fin// ltNge// fun_ge0.
Qed.

Lemma eq_measure_integral m2 m1 (f : T -> \bar R) :
(forall A, A `<=` D -> m1 A = m2 A) ->
(forall A, measurable A -> A `<=` D -> m1 A = m2 A) ->
\int[m1]_(x in D) f x = \int[m2]_(x in D) f x.
Proof.
move=> m12; rewrite /integral funepos_restrict funeneg_restrict.
by congr (ereal_sup _ - ereal_sup _)%E; rewrite eqEsubset; split;
apply: eq_measure_integral0 => A /m12.
apply: eq_measure_integral0 => A /m12 // /[apply].
Qed.

End eq_measure_integral.
Expand Down Expand Up @@ -2362,7 +2362,7 @@ have [/[!inE] aD|aD] := boolP (a \in D).
rewrite ge0_integral_dirac//; last exact/emeasurable_fun_funeneg.
by rewrite [in RHS](funeposneg f) indicE mem_set// mul1e.
rewrite indicE (negbTE aD) mul0e -(integral_measure_zero D f)//.
apply: eq_measure_integral => //= S DS; rewrite /dirac indicE memNset// => /DS.
apply: eq_measure_integral => //= S mS DS; rewrite /dirac indicE memNset// => /DS.
by rewrite notin_set in aD.
Qed.

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