@@ -20,6 +20,7 @@ From mathcomp Require Import topology sequences normedtype numfun.
2020(* reals; it is 0 if I = set0 and sup(\sum_A a) where A *)
2121(* is a finite set included in I o.w. *)
2222(* summable D f := \esum_(x in D) `| f x | < +oo *)
23+ (* sum f := esum [set: T] f^\+ - esum [set: T] f^\-. *)
2324(* ``` *)
2425(* *)
2526(***************************************************************************** *)
@@ -715,29 +716,8 @@ Qed.
715716
716717End esumB.
717718
718- Section Sum.
719- Context {R : realType} {T : choiceType}.
720- Implicit Types (f : T -> \bar R) (x y : \bar R).
721-
722- Lemma ge0_funeneg f t : (forall t, 0 <= f t) -> f^\- t = 0.
723- Proof . by move => ?; rewrite funenegE max_r// ?lerN0 oppe_le0. Qed .
724-
725- Lemma ge0_funepos f t : (forall t, 0 <= f t) -> f^\+ t = f t.
726- Proof . by move=> ?; rewrite funeposE max_l. Qed .
727-
728- Lemma funepos_cst0 t : (@cst T _ 0)^\+ t = 0 :> \bar R.
729- Proof . by rewrite funeposE maxxx. Qed .
730-
731- Lemma funeneg_cst0 t : (@cst T _ 0)^\- t = 0 :> \bar R.
732- Proof . by rewrite funenegE oppe0 maxxx. Qed .
733-
734- Lemma le_funepos f1 f2 : (forall t, f1 t <= f2 t) ->
735- (forall t, f1^\+ t <= f2^\+ t).
736- Proof . by move=> le_f x; rewrite (@funepos_le _ _ setT)// inE. Qed .
737-
738- Definition sum f : \bar R := esum [set: T] f^\+ - esum [set: T] f^\-.
739-
740- End Sum.
719+ Definition sum {R : realType} {T : choiceType} (f : T -> \bar R) : \bar R :=
720+ esum [set: T] f^\+ - esum [set: T] f^\-.
741721
742722Section SumTheory.
743723Context {R : realType} {T : choiceType}.
@@ -817,9 +797,10 @@ Lemma summable_le_sum f g : summable [set : T] g ->
817797 (forall x, f x <= g x) -> sum f <= sum g.
818798Proof .
819799move=> sg leS; rewrite /sum leeB//.
820- by apply: le_esum => ? ?; exact: le_funepos .
800+ by apply: le_esum => ? ?; apply: (@funepos_le _ _ setT) => //; rewrite inE .
821801apply le_esum => t _.
822- by rewrite -!funeposN; apply: le_funepos => ?; rewrite leeN2.
802+ rewrite -!funeposN.
803+ by apply: (@funepos_le _ _ setT); rewrite ?inE// => ? ?; rewrite leeN2.
823804Qed .
824805
825806Lemma summable_esum_funepos A f :
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