Skip to content

Commit 777aaa6

Browse files
smorel394morel
andcommitted
refactor(Topology/Sheaves): harmonize names (#36074)
Make the name of the pullback/pushforward adjunction for presheaves `Presheaf.pullbackPushforwardAdjunction`, so it follows the same convention as the name of the similar adjunction for sheaves. Co-authored-by: morel <smorel@math.princeton.edu>
1 parent fa360fd commit 777aaa6

File tree

2 files changed

+22
-19
lines changed

2 files changed

+22
-19
lines changed

Mathlib/Topology/Sheaves/Presheaf.lean

Lines changed: 7 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -27,7 +27,7 @@ and for `ℱ : X.Presheaf C` provide the natural isomorphisms
2727
2828
We also define the functors `pullback C f : Y.Presheaf C ⥤ X.Presheaf c`,
2929
and provide their adjunction at
30-
`TopCat.Presheaf.pushforwardPullbackAdjunction`.
30+
`TopCat.Presheaf.pullbackPushforwardAdjunction`.
3131
-/
3232

3333
@[expose] public section
@@ -269,20 +269,23 @@ def pullback {X Y : TopCat.{v}} (f : X ⟶ Y) : Y.Presheaf C ⥤ X.Presheaf C :=
269269
(Opens.map f).op.lan
270270

271271
/-- The pullback and pushforward along a continuous map are adjoint to each other. -/
272-
def pushforwardPullbackAdjunction {X Y : TopCat.{v}} (f : X ⟶ Y) :
272+
def pullbackPushforwardAdjunction {X Y : TopCat.{v}} (f : X ⟶ Y) :
273273
pullback C f ⊣ pushforward C f :=
274274
Functor.lanAdjunction _ _
275275

276+
@[deprecated (since := "2026-03-03")]
277+
alias pushforwardPullbackAdjunction := pullbackPushforwardAdjunction
278+
276279
/-- Pulling back along a homeomorphism is the same as pushing forward along its inverse. -/
277280
def pullbackHomIsoPushforwardInv {X Y : TopCat.{v}} (H : X ≅ Y) :
278281
pullback C H.hom ≅ pushforward C H.inv :=
279-
Adjunction.leftAdjointUniq (pushforwardPullbackAdjunction C H.hom)
282+
Adjunction.leftAdjointUniq (pullbackPushforwardAdjunction C H.hom)
280283
(presheafEquivOfIso C H.symm).toAdjunction
281284

282285
/-- Pulling back along the inverse of a homeomorphism is the same as pushing forward along it. -/
283286
def pullbackInvIsoPushforwardHom {X Y : TopCat.{v}} (H : X ≅ Y) :
284287
pullback C H.inv ≅ pushforward C H.hom :=
285-
Adjunction.leftAdjointUniq (pushforwardPullbackAdjunction C H.inv)
288+
Adjunction.leftAdjointUniq (pullbackPushforwardAdjunction C H.inv)
286289
(presheafEquivOfIso C H).toAdjunction
287290

288291
variable {C}

Mathlib/Topology/Sheaves/Stalks.lean

Lines changed: 15 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -227,15 +227,15 @@ section stalkPullback
227227
/-- The morphism `ℱ_{f x} ⟶ (f⁻¹ℱ)ₓ` that factors through `(f_*f⁻¹ℱ)_{f x}`. -/
228228
def stalkPullbackHom (f : X ⟶ Y) (F : Y.Presheaf C) (x : X) :
229229
F.stalk (f x) ⟶ ((pullback C f).obj F).stalk x :=
230-
(stalkFunctor _ (f x)).map ((pushforwardPullbackAdjunction C f).unit.app F) ≫
230+
(stalkFunctor _ (f x)).map ((pullbackPushforwardAdjunction C f).unit.app F) ≫
231231
stalkPushforward _ _ _ x
232232

233233
set_option backward.isDefEq.respectTransparency false in
234234
@[reassoc (attr := simp)]
235235
lemma germ_stalkPullbackHom
236236
(f : X ⟶ Y) (F : Y.Presheaf C) (x : X) (U : Opens Y) (hU : f x ∈ U) :
237237
F.germ U (f x) hU ≫ stalkPullbackHom C f F x =
238-
((pushforwardPullbackAdjunction C f).unit.app F).app _ ≫
238+
((pullbackPushforwardAdjunction C f).unit.app F).app _ ≫
239239
((pullback C f).obj F).germ ((Opens.map f).obj U) x hU := by
240240
simp [stalkPullbackHom, germ, stalkFunctor, stalkPushforward]
241241

@@ -253,23 +253,23 @@ variable {C} in
253253
lemma pullback_obj_obj_ext {Z : C} {f : X ⟶ Y} {F : Y.Presheaf C} (U : (Opens X)ᵒᵖ)
254254
{φ ψ : ((pullback C f).obj F).obj U ⟶ Z}
255255
(h : ∀ (V : Opens Y) (hV : U.unop ≤ (Opens.map f).obj V),
256-
((pushforwardPullbackAdjunction C f).unit.app F).app (op V) ≫
256+
((pullbackPushforwardAdjunction C f).unit.app F).app (op V) ≫
257257
((pullback C f).obj F).map (homOfLE hV).op ≫ φ =
258-
((pushforwardPullbackAdjunction C f).unit.app F).app (op V) ≫
258+
((pullbackPushforwardAdjunction C f).unit.app F).app (op V) ≫
259259
((pullback C f).obj F).map (homOfLE hV).op ≫ ψ) : φ = ψ := by
260260
apply ((Opens.map f).op.isPointwiseLeftKanExtensionLeftKanExtensionUnit F _).hom_ext
261261
rintro ⟨⟨V⟩, ⟨⟩, ⟨b⟩⟩
262-
simpa [pushforwardPullbackAdjunction, Functor.lanAdjunction_unit]
262+
simpa [pullbackPushforwardAdjunction, Functor.lanAdjunction_unit]
263263
using h V (leOfHom b)
264264

265265
@[reassoc (attr := simp)]
266-
lemma pushforwardPullbackAdjunction_unit_pullback_map_germToPullbackStalk
266+
lemma pullbackPushforwardAdjunction_unit_pullback_map_germToPullbackStalk
267267
(f : X ⟶ Y) (F : Y.Presheaf C) (U : Opens X) (x : X) (hx : x ∈ U) (V : Opens Y)
268268
(hV : U ≤ (Opens.map f).obj V) :
269-
((pushforwardPullbackAdjunction C f).unit.app F).app (op V) ≫
269+
((pullbackPushforwardAdjunction C f).unit.app F).app (op V) ≫
270270
((pullback C f).obj F).map (homOfLE hV).op ≫ germToPullbackStalk C f F U x hx =
271271
F.germ _ (f x) (hV hx) := by
272-
simpa [pushforwardPullbackAdjunction] using
272+
simpa [pullbackPushforwardAdjunction] using
273273
((Opens.map f).op.isPointwiseLeftKanExtensionLeftKanExtensionUnit F (op U)).fac _
274274
(CostructuredArrow.mk (homOfLE hV).op)
275275

@@ -281,15 +281,15 @@ lemma germToPullbackStalk_stalkPullbackHom
281281
((pullback C f).obj F).germ _ x hx := by
282282
ext V hV
283283
dsimp
284-
simp only [pushforwardPullbackAdjunction_unit_pullback_map_germToPullbackStalk_assoc,
284+
simp only [pullbackPushforwardAdjunction_unit_pullback_map_germToPullbackStalk_assoc,
285285
germ_stalkPullbackHom, germ_res]
286286

287287
@[reassoc (attr := simp)]
288-
lemma pushforwardPullbackAdjunction_unit_app_app_germToPullbackStalk
288+
lemma pullbackPushforwardAdjunction_unit_app_app_germToPullbackStalk
289289
(f : X ⟶ Y) (F : Y.Presheaf C) (V : (Opens Y)ᵒᵖ) (x : X) (hx : f x ∈ V.unop) :
290-
((pushforwardPullbackAdjunction C f).unit.app F).app V ≫ germToPullbackStalk C f F _ x hx =
290+
((pullbackPushforwardAdjunction C f).unit.app F).app V ≫ germToPullbackStalk C f F _ x hx =
291291
F.germ _ (f x) hx := by
292-
simpa using pushforwardPullbackAdjunction_unit_pullback_map_germToPullbackStalk
292+
simpa using pullbackPushforwardAdjunction_unit_pullback_map_germToPullbackStalk
293293
C f F ((Opens.map f).obj V.unop) x hx V.unop (by rfl)
294294

295295
set_option backward.isDefEq.respectTransparency false in
@@ -305,8 +305,8 @@ def stalkPullbackInv (f : X ⟶ Y) (F : Y.Presheaf C) (x : X) :
305305
ext W hW
306306
dsimp [OpenNhds.inclusion]
307307
rw [Category.comp_id, ← Functor.map_comp_assoc,
308-
pushforwardPullbackAdjunction_unit_pullback_map_germToPullbackStalk]
309-
erw [pushforwardPullbackAdjunction_unit_pullback_map_germToPullbackStalk] } }
308+
pullbackPushforwardAdjunction_unit_pullback_map_germToPullbackStalk]
309+
erw [pullbackPushforwardAdjunction_unit_pullback_map_germToPullbackStalk] } }
310310

311311
@[reassoc (attr := simp)]
312312
lemma germ_stalkPullbackInv (f : X ⟶ Y) (F : Y.Presheaf C) (x : X) (V : Opens X) (hV : x ∈ V) :
@@ -324,7 +324,7 @@ def stalkPullbackIso (f : X ⟶ Y) (F : Y.Presheaf C) (x : X) :
324324
ext U hU
325325
dsimp
326326
rw [germ_stalkPullbackHom_assoc, germ_stalkPullbackInv, Category.comp_id,
327-
pushforwardPullbackAdjunction_unit_app_app_germToPullbackStalk]
327+
pullbackPushforwardAdjunction_unit_app_app_germToPullbackStalk]
328328
inv_hom_id := by
329329
ext V hV
330330
dsimp

0 commit comments

Comments
 (0)