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rename setD_closed to setSD_closed #1243

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2 changes: 2 additions & 0 deletions CHANGELOG_UNRELEASED.md
Original file line number Diff line number Diff line change
Expand Up @@ -81,6 +81,8 @@

- in `ftc.v`:
+ `FTC1` -> `FTC1_lebesgue_pt`
- in `measure.v`:
+ `setD_closed` -> `setSD_closed`

### Generalized

Expand Down
18 changes: 11 additions & 7 deletions theories/measure.v
Original file line number Diff line number Diff line change
Expand Up @@ -186,7 +186,9 @@ From HB Require Import structures.
(* intersection *)
(* setU_closed G == the set of sets G is closed under finite union *)
(* setC_closed G == the set of sets G is closed under complement *)
(* setD_closed G == the set of sets G is closed under difference *)
(* setSD_closed G == the set of sets G is closed under proper *)
(* difference *)
(* setDI_closed G == the set of sets G is closed under difference *)
(* ndseq_closed G == the set of sets G is closed under non-decreasing *)
(* countable union *)
(* niseq_closed G == the set of sets G is closed under non-increasing *)
Expand Down Expand Up @@ -350,7 +352,7 @@ Context {T} (C : set (set T) -> Prop) (D : set T) (G : set (set T)).
Definition setC_closed := forall A, G A -> G (~` A).
Definition setI_closed := forall A B, G A -> G B -> G (A `&` B).
Definition setU_closed := forall A B, G A -> G B -> G (A `|` B).
Definition setD_closed := forall A B, B `<=` A -> G A -> G B -> G (A `\` B).
Definition setSD_closed := forall A B, B `<=` A -> G A -> G B -> G (A `\` B).
Definition setDI_closed := forall A B, G A -> G B -> G (A `\` B).

Definition fin_bigcap_closed :=
Expand Down Expand Up @@ -405,13 +407,15 @@ Definition dynkin := [/\ G setT, setC_closed & trivIset_closed].
because this definition corresponds to "classe monotone" in several
French references, e.g., the definition of "classe monotone" on the French wikipedia. *)
Definition lambda_system :=
[/\ forall A, G A -> A `<=` D, G D, setD_closed & ndseq_closed].
[/\ forall A, G A -> A `<=` D, G D, setSD_closed & ndseq_closed].

Definition monotone := ndseq_closed /\ niseq_closed.

End classes.
#[deprecated(since="mathcomp-analysis 1.2.0", note="renamed `lambda_system`")]
Notation monotone_class := lambda_system (only parsing).
#[deprecated(since="mathcomp-analysis 1.3.0", note="renamed `setSD_closed`")]
Notation setD_closed := setSD_closed (only parsing).

Lemma powerset_sigma_ring (T : Type) (D : set T) :
sigma_ring [set X | X `<=` D].
Expand Down Expand Up @@ -480,7 +484,7 @@ by rewrite setICA; apply: GI => //; apply: GA.
Qed.

Lemma sedDI_closedP T (G : set (set T)) :
setDI_closed G <-> (setI_closed G /\ setD_closed G).
setDI_closed G <-> (setI_closed G /\ setSD_closed G).
Proof.
split=> [GDI|[GI GD]].
by split=> A B => [|AB] => GA GB; rewrite -?setDD//; do ?apply: (GDI).
Expand All @@ -502,7 +506,7 @@ Qed.
Lemma sigma_algebraP T U (C : set (set T)) :
(forall X, C X -> X `<=` U) ->
sigma_algebra U C <->
[/\ C U, setD_closed C, ndseq_closed C & setI_closed C].
[/\ C U, setSD_closed C, ndseq_closed C & setI_closed C].
Proof.
move=> C_subU; split => [[C0 CD CU]|[DT DC DU DI]]; split.
- by rewrite -(setD0 U); apply: CD.
Expand Down Expand Up @@ -737,7 +741,7 @@ suff: setI_closed <<l D, G >>.
by apply/sigma_algebraP; case: lambdaDG.
pose H := <<l D, G >>.
pose H_ A := [set X | H X /\ H (X `&` A)].
have setDH_ A : setD_closed (H_ A).
have setDH_ A : setSD_closed (H_ A).
move=> X Y XY [HX HXA] [HY HYA]; case: lambdaDG => h _ setDH _; split.
exact: setDH.
rewrite (_ : _ `&` _ = (X `&` A) `\` (Y `&` A)); last first.
Expand Down Expand Up @@ -3702,7 +3706,7 @@ Proof.
move=> sDHD; set E := [set A | [/\ measurable A, m1 A = m2 A & A `<=` D] ].
have HE : H `<=` E.
by move=> X HX; rewrite /E /=; split; [exact: Hm|exact: m1m2|case: HX].
have setDE : setD_closed E.
have setDE : setSD_closed E.
move=> A B BA [mA m1m2A AD] [mB m1m2B BD]; split; first exact: measurableD.
- rewrite measureD//; last first.
by rewrite (le_lt_trans _ m1oo)//; apply: le_measure => // /[!inE].
Expand Down
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