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fixing build
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zstone1 committed Oct 23, 2024
1 parent 425fba5 commit 108e886
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44 changes: 21 additions & 23 deletions CHANGELOG_UNRELEASED.md
Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,27 @@
+ `num_topology.v`
+ `quotient_topology.v`

- in file `separation_axioms.v`,
+ new lemmas `compact_normal_local`, and `compact_normal`.

- in file `topology_theory/one_point_compactification.v`,
+ new definitions `one_point_compactification`, and `one_point_nbhs`.
+ new lemmas `one_point_compactification_compact`,
`one_point_compactification_some_nbhs`,
`one_point_compactification_some_continuous`,
`one_point_compactification_open_some`,
`one_point_compactification_weak_topology`, and
`one_point_compactification_hausdorff`.

- in file `normedtype.v`,
+ new definition `type` (in module `completely_regular_uniformity`)
+ new lemmas `normal_completely_regular`,
`one_point_compactification_completely_reg`,
`nbhs_one_point_compactification_weakE`,
`locally_compact_completely_regular`, and
`completely_regular_regular`.


### Changed

- The file `topology.v` has been split into several files in the directory
Expand Down Expand Up @@ -168,29 +189,6 @@

- moved from `topology.v` to `boolp.v`:
+ lemmas `bigmax_geP`, `bigmax_gtP`, `bigmin_leP`, `bigmin_ltP`
- in file `normedtype.v`,
+ new definition `type` (in module `completely_regular_uniformity`)
+ new lemmas `normal_completely_regular`, and
`locally_compact_completely_regular`.
+ new definition `type`.
+ new lemmas `normal_completely_regular`,
`one_point_compactification_completely_reg`,
`nbhs_one_point_compactification_weakE`,
`locally_compact_completely_regular`, and
`completely_regular_regular`.

- in file `topology.v`,
+ new definitions `one_point_compactification`, and `one_point_nbhs`.
+ new lemmas `compact_normal_local`, and `compact_normal`.
+ new lemmas `one_point_compactification_compact`,
`one_point_compactification_some_nbhs`,
`one_point_compactification_some_continuous`,
`one_point_compactification_open_some`,
`one_point_compactification_weak_topology`, and
`one_point_compactification_hausdorff`.
- in file `separation_axioms.v`
+ new lemmas `compact_normal_local` and `compact_normal`.

### Changed

- in file `normedtype.v`,
Expand Down
30 changes: 12 additions & 18 deletions theories/normedtype.v
Original file line number Diff line number Diff line change
Expand Up @@ -3692,6 +3692,7 @@ Proof. exact: (normal_spaceP 0%N 1%N). Qed.
End normalP.

Section completely_regular.
Context {R : realType}.

(**md This is equivalent to uniformizable. Note there is a subtle
distinction between being uniformizable and being uniformType.
Expand All @@ -3704,8 +3705,6 @@ Section completely_regular.
Definition completely_regular_space (T : topologicalType) :=
forall (a : T) (B : set T), closed B -> ~ B a -> uniform_separator [set a] B.

(* Ideally, R should be an instance of realType here,
rather than a section variable. *)
Lemma point_uniform_separator {T : uniformType} (x : T) (B : set T) :
closed B -> ~ B x -> uniform_separator [set x] B.
Proof.
Expand All @@ -3719,13 +3718,7 @@ Qed.

Lemma uniform_completely_regular {T : uniformType} :
@completely_regular_space T.
<<<<<<< HEAD
Proof.
by move=> x B clB Bx; exact: point_uniform_separator.
Qed.
=======
Proof. by move=> x B clB Bx; exact: point_uniform_separator. Qed.
>>>>>>> 4b77400b (just linting)

Lemma normal_completely_regular {T : topologicalType} :
normal_space T -> accessible_space T -> completely_regular_space T.
Expand All @@ -3745,10 +3738,10 @@ End completely_regular.

Module completely_regular_uniformity.
Section completely_regular_uniformity.
Context {X : topologicalType}.
Context {R : realType} {X : topologicalType}.
Hypothesis crs : completely_regular_space X.

Let X' : uniformType := @sup_topology X {f : X -> Rdefinitions.R | continuous f}
Let X' : uniformType := @sup_topology X {f : X -> R | continuous f}
(fun f => Uniform.class (weak_topology (projT1 f))).

Let completely_regular_nbhsE : @nbhs X X = nbhs_ (@entourage X').
Expand All @@ -3763,7 +3756,7 @@ move=> U; wlog oU : U / @open X U.
move=> /[dup] nUx /nbhs_singleton Ux.
have ufs : uniform_separator [set x] (~` U).
by apply: crs; [exact: open_closedC | exact].
have /uniform_separatorP := ufs => /(_ Rdefinitions.R)[f [ctsf f01 fx0 fU1]].
have /uniform_separatorP := ufs => /(_ R)[f [ctsf f01 fx0 fU1]].
rewrite -nbhs_entourageE /entourage /= /sup_ent /= smallest_filter_finI.
pose E := map_pair f @^-1` (fun pq => ball pq.1 1 pq.2).
exists E; first last.
Expand All @@ -3773,7 +3766,7 @@ exists E; first last.
suff -> : f z = 1 by rewrite normr1 ltxx.
by apply: fU1; exists z.
move=> r /= [_]; apply => /=.
pose f' : {classic {f : X -> Rdefinitions.R | continuous f}} := exist _ f ctsf.
pose f' : {classic {f : X -> R | continuous f}} := exist _ f ctsf.
suff /asboolP entE : @entourage (weak_topology f) (f', E).2.
by exists (exist _ (f', E) entE).
exists (fun pq => ball pq.1 1 pq.2) => //=.
Expand Down Expand Up @@ -3807,18 +3800,19 @@ Hypothesis hsdf : hausdorff_space X.

Let opc := @one_point_compactification X.

Lemma one_point_compactification_completely_reg :
Lemma one_point_compactification_completely_reg :
completely_regular_space opc.
Proof.
apply: normal_completely_regular.
apply: (@normal_completely_regular R).
apply: compact_normal.
exact: one_point_compactification_hausdorff.
exact: one_point_compactification_compact.
by apply: hausdorff_accessible; exact: one_point_compactification_hausdorff.
Qed.

#[local]
HB.instance Definition _ := Uniform.copy opc
(completely_regular_uniformity.type
(@completely_regular_uniformity.type R _
one_point_compactification_completely_reg).

Let X' := @weak_topology X opc Some.
Expand All @@ -3840,11 +3834,11 @@ Proof. exact: uniform_completely_regular. Qed.

End locally_compact_uniform.

Lemma completely_regular_regular {X : topologicalType} :
Lemma completely_regular_regular {R : realType} {X : topologicalType} :
completely_regular_space X -> @regular_space X.
Proof.
move=> crsX; pose P' := completely_regular_uniformity.type crsX.
exact: @uniform_regular P'.
move=> crsX; pose P' := @completely_regular_uniformity.type R _ crsX.
exact: (@uniform_regular P').
Qed.

Section pseudometric_normal.
Expand Down
25 changes: 15 additions & 10 deletions theories/topology_theory/one_point_compactification.v
Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
From HB Require Import structures.
From mathcomp Require Import all_ssreflect all_algebra all_classical.
From mathcomp Require Import signed topology_structure uniform_structure.
From mathcomp Require Import pseudometric_structure compact.
From mathcomp Require Import pseudometric_structure compact weak_topology.

(**md**************************************************************************)
(* # One Point Compactifications *)
Expand All @@ -14,6 +14,10 @@ From mathcomp Require Import pseudometric_structure compact.
(* as an alias of `option X` *)
(******************************************************************************)

Local Open Scope classical_set_scope.
Local Open Scope ring_scope.


Definition one_point_compactification (X : Type) : Type := option X.

Section one_point_compactification.
Expand Down Expand Up @@ -63,7 +67,7 @@ HB.instance Definition _ := hasNbhs.Build opc one_point_nbhs.
HB.instance Definition _ := @Nbhs_isNbhsTopological.Build opc
one_point_filter one_point_singleton one_point_nbhs_nbhs.

Lemma opc_compact : compact [set: opc].
Lemma one_point_compactification_compact : compact [set: opc].
Proof.
apply/compact_near_coveringP => ? F /= P FF FT.
have [//| [U i [[W /= [cptW cW WU nfI UIP]]]]] := FT None.
Expand All @@ -81,29 +85,30 @@ move=> ?; apply: (UIP (Some z,j)); split => //=.
exact: (near nfI _).
Unshelve. all: by end_near. Qed.

Lemma opc_some_nbhs (x : X) (U : set X) :
Lemma one_point_compactification_some_nbhs (x : X) (U : set X) :
nbhs x U -> @nbhs _ opc (Some x) (Some @` U).
Proof.
rewrite {2}/nbhs /= nbhs_simpl /= => /filterS; apply; exact: preimage_image.
Qed.

Lemma opc_some_continuous : continuous (Some : X -> opc).
Lemma one_point_compactification_some_continuous : continuous (Some : X -> opc).
Proof. by move=> x U. Qed.

Lemma opc_open_some (U : set X) : open U -> @open opc (Some @` U).
Lemma one_point_compactification_open_some (U : set X) :
open U -> @open opc (Some @` U).
Proof.
rewrite ?openE /= => Uo ? /= [x /[swap] <- Ux] /=.
by apply: opc_some_nbhs; apply: Uo.
by apply: one_point_compactification_some_nbhs; apply: Uo.
Qed.

Lemma opc_weak_topology :
Lemma one_point_compactification_weak_topology :
@nbhs _ (@weak_topology X opc Some) = @nbhs _ X.
Proof.
rewrite funeq2E=> x U; apply/propeqP; split; rewrite /(@nbhs _ (weak_topology _)) /=.
case => V [[/= W] oW <- /= Ws] /filterS; apply; apply: opc_some_continuous.
exact: oW.
case => V [[/= W] oW <- /= Ws] /filterS; apply.
by apply: one_point_compactification_some_continuous; exact: oW.
rewrite nbhsE; case => V [? ? ?]; exists V; split => //.
exists (Some @` V); first exact: opc_open_some.
exists (Some @` V); first exact: one_point_compactification_open_some.
rewrite eqEsubset; split => z /=; first by case=> ? /[swap] /Some_inj ->.
by move=> ?; exists z.
Qed.
Expand Down

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