category_theory.limits.over | Mathlib porting status

Changes since the initial port

The following section lists changes to this file in mathlib3 and mathlib4 that occured after the initial port. Most recent changes are shown first. Hovering over a commit will show all commits associated with the same mathlib3 commit.

Changes in mathlib3

3e0dd193

(last sync)

Changes in mathlib3port

mathlib3

mathlib3port

4f4a1c87

bump to nightly-2024-04-06-08

mathlib commit https://github.com/leanprover-community/mathlib/commit/65a1391a0106c9204fe45bc73a039f056558cb83

e34029c9

Diff

@@ -3,7 +3,7 @@ Copyright (c) 2018 Johan Commelin. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Johan Commelin, Reid Barton, Bhavik Mehta
 -/
-import CategoryTheory.Over
+import CategoryTheory.Comma.Over
 import CategoryTheory.Adjunction.Opposites
 import CategoryTheory.Limits.Preserves.Basic
 import CategoryTheory.Limits.Shapes.Pullbacks

4f4a1c87

bump to nightly-2023-09-24-06

mathlib commit https://github.com/leanprover-community/mathlib/commit/ce64cd319bb6b3e82f31c2d38e79080d377be451

5655435f

Diff

@@ -3,12 +3,12 @@ Copyright (c) 2018 Johan Commelin. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Johan Commelin, Reid Barton, Bhavik Mehta
 -/
-import Mathbin.CategoryTheory.Over
-import Mathbin.CategoryTheory.Adjunction.Opposites
-import Mathbin.CategoryTheory.Limits.Preserves.Basic
-import Mathbin.CategoryTheory.Limits.Shapes.Pullbacks
-import Mathbin.CategoryTheory.Limits.Creates
-import Mathbin.CategoryTheory.Limits.Comma
+import CategoryTheory.Over
+import CategoryTheory.Adjunction.Opposites
+import CategoryTheory.Limits.Preserves.Basic
+import CategoryTheory.Limits.Shapes.Pullbacks
+import CategoryTheory.Limits.Creates
+import CategoryTheory.Limits.Comma
 
 #align_import category_theory.limits.over from "leanprover-community/mathlib"@"4f4a1c875d0baa92ab5d92f3fb1bb258ad9f3e5b"

4f4a1c87

bump to nightly-2023-08-31-06

mathlib commit https://github.com/leanprover-community/mathlib/commit/ffde2d8a6e689149e44fd95fa862c23a57f8c780

8d006b5f

Diff

@@ -56,10 +56,10 @@ instance [HasColimitsOfShape J C] : HasColimitsOfShape J (Over X) where
 instance [HasColimits C] : HasColimits (Over X) :=
   ⟨inferInstance⟩
 
-#print CategoryTheory.Over.createsColimits /-
-instance createsColimits : CreatesColimits (forget X) :=
-  CostructuredArrow.createsColimits
-#align category_theory.over.creates_colimits CategoryTheory.Over.createsColimits
+#print CategoryTheory.Over.createsColimitsOfSize /-
+instance createsColimitsOfSize : CreatesColimits (forget X) :=
+  CostructuredArrow.createsColimitsOfSize
+#align category_theory.over.creates_colimits CategoryTheory.Over.createsColimitsOfSize
 -/
 
 -- We can automatically infer that the forgetful functor preserves and reflects colimits.
@@ -174,10 +174,10 @@ theorem mono_iff_mono_right [HasPullbacks C] {f g : Under X} (h : f ⟶ g) : Mon
 #align category_theory.under.mono_iff_mono_right CategoryTheory.Under.mono_iff_mono_right
 -/
 
-#print CategoryTheory.Under.createsLimits /-
-instance createsLimits : CreatesLimits (forget X) :=
-  StructuredArrow.createsLimits
-#align category_theory.under.creates_limits CategoryTheory.Under.createsLimits
+#print CategoryTheory.Under.createsLimitsOfSize /-
+instance createsLimitsOfSize : CreatesLimits (forget X) :=
+  StructuredArrow.createsLimitsOfSize
+#align category_theory.under.creates_limits CategoryTheory.Under.createsLimitsOfSize
 -/
 
 -- We can automatically infer that the forgetful functor preserves and reflects limits.

4f4a1c87

bump to nightly-2023-07-20-09

mathlib commit https://github.com/leanprover-community/mathlib/commit/8ea5598db6caeddde6cb734aa179cc2408dbd345

9c56d0dd

Diff

@@ -2,11 +2,6 @@
 Copyright (c) 2018 Johan Commelin. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Johan Commelin, Reid Barton, Bhavik Mehta
-
-! This file was ported from Lean 3 source module category_theory.limits.over
-! leanprover-community/mathlib commit 4f4a1c875d0baa92ab5d92f3fb1bb258ad9f3e5b
-! Please do not edit these lines, except to modify the commit id
-! if you have ported upstream changes.
 -/
 import Mathbin.CategoryTheory.Over
 import Mathbin.CategoryTheory.Adjunction.Opposites
@@ -15,6 +10,8 @@ import Mathbin.CategoryTheory.Limits.Shapes.Pullbacks
 import Mathbin.CategoryTheory.Limits.Creates
 import Mathbin.CategoryTheory.Limits.Comma
 
+#align_import category_theory.limits.over from "leanprover-community/mathlib"@"4f4a1c875d0baa92ab5d92f3fb1bb258ad9f3e5b"
+
 /-!
 # Limits and colimits in the over and under categories

4f4a1c87

bump to nightly-2023-05-28-04

mathlib commit https://github.com/leanprover-community/mathlib/commit/917c3c072e487b3cccdbfeff17e75b40e45f66cb

6797a637

Diff

@@ -116,10 +116,7 @@ def mapPullbackAdj {A B : C} (f : A ⟶ B) : Over.map f ⊣ pullback f :=
             refine' Y.left ≫ pullback.fst
             dsimp
             rw [← over.w Y, category.assoc, pullback.condition, category.assoc]; rfl
-          left_inv := fun X => by
-            ext
-            dsimp
-            simp
+          left_inv := fun X => by ext; dsimp; simp
           right_inv := fun Y => by
             ext; dsimp
             simp only [pullback.lift_fst]

4f4a1c87

bump to nightly-2023-04-16-02

mathlib commit https://github.com/leanprover-community/mathlib/commit/4f4a1c875d0baa92ab5d92f3fb1bb258ad9f3e5b

63127953

Diff

@@ -4,7 +4,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Johan Commelin, Reid Barton, Bhavik Mehta
 
 ! This file was ported from Lean 3 source module category_theory.limits.over
-! leanprover-community/mathlib commit 3e0dd193514c9380edc69f1da92e80c02713c41d
+! leanprover-community/mathlib commit 4f4a1c875d0baa92ab5d92f3fb1bb258ad9f3e5b
 ! Please do not edit these lines, except to modify the commit id
 ! if you have ported upstream changes.
 -/
@@ -18,6 +18,9 @@ import Mathbin.CategoryTheory.Limits.Comma
 /-!
 # Limits and colimits in the over and under categories
 
+> THIS FILE IS SYNCHRONIZED WITH MATHLIB4.
+> Any changes to this file require a corresponding PR to mathlib4.
+
 Show that the forgetful functor `forget X : over X ⥤ C` creates colimits, and hence `over X` has
 any colimits that `C` has (as well as the dual that `forget X : under X ⟶ C` creates limits).

3e0dd193

bump to nightly-2023-04-14-22

mathlib commit https://github.com/leanprover-community/mathlib/commit/7ebf83ed9c262adbf983ef64d5e8c2ae94b625f4

60fdc414

Diff

@@ -44,19 +44,23 @@ variable {X : C}
 
 namespace CategoryTheory.Over
 
+#print CategoryTheory.Over.hasColimit_of_hasColimit_comp_forget /-
 instance hasColimit_of_hasColimit_comp_forget (F : J ⥤ Over X) [i : HasColimit (F ⋙ forget X)] :
     HasColimit F :=
   @CostructuredArrow.hasColimit _ _ _ _ i _
 #align category_theory.over.has_colimit_of_has_colimit_comp_forget CategoryTheory.Over.hasColimit_of_hasColimit_comp_forget
+-/
 
 instance [HasColimitsOfShape J C] : HasColimitsOfShape J (Over X) where
 
 instance [HasColimits C] : HasColimits (Over X) :=
   ⟨inferInstance⟩
 
+#print CategoryTheory.Over.createsColimits /-
 instance createsColimits : CreatesColimits (forget X) :=
   CostructuredArrow.createsColimits
 #align category_theory.over.creates_colimits CategoryTheory.Over.createsColimits
+-/
 
 -- We can automatically infer that the forgetful functor preserves and reflects colimits.
 example [HasColimits C] : PreservesColimits (forget X) :=
@@ -65,13 +69,17 @@ example [HasColimits C] : PreservesColimits (forget X) :=
 example : ReflectsColimits (forget X) :=
   inferInstance
 
+#print CategoryTheory.Over.epi_left_of_epi /-
 theorem epi_left_of_epi [HasPushouts C] {f g : Over X} (h : f ⟶ g) [Epi h] : Epi h.left :=
   CostructuredArrow.epi_left_of_epi _
 #align category_theory.over.epi_left_of_epi CategoryTheory.Over.epi_left_of_epi
+-/
 
+#print CategoryTheory.Over.epi_iff_epi_left /-
 theorem epi_iff_epi_left [HasPushouts C] {f g : Over X} (h : f ⟶ g) : Epi h ↔ Epi h.left :=
   CostructuredArrow.epi_iff_epi_left _
 #align category_theory.over.epi_iff_epi_left CategoryTheory.Over.epi_iff_epi_left
+-/
 
 section
 
@@ -79,6 +87,7 @@ variable [HasPullbacks C]
 
 open Tactic
 
+#print CategoryTheory.Over.pullback /-
 /-- When `C` has pullbacks, a morphism `f : X ⟶ Y` induces a functor `over Y ⥤ over X`,
 by pulling back a morphism along `f`. -/
 @[simps]
@@ -89,7 +98,9 @@ def pullback {X Y : C} (f : X ⟶ Y) : Over Y ⥤ Over X
     Over.homMk (pullback.lift (pullback.fst ≫ k.left) pullback.snd (by simp [pullback.condition]))
       (by tidy)
 #align category_theory.over.pullback CategoryTheory.Over.pullback
+-/
 
+#print CategoryTheory.Over.mapPullbackAdj /-
 /-- `over.map f` is left adjoint to `over.pullback f`. -/
 def mapPullbackAdj {A B : C} (f : A ⟶ B) : Over.map f ⊣ pullback f :=
   Adjunction.mkOfHomEquiv
@@ -113,21 +124,28 @@ def mapPullbackAdj {A B : C} (f : A ⟶ B) : Over.map f ⊣ pullback f :=
             rw [pullback.lift_snd, ← over.w Y]
             rfl } }
 #align category_theory.over.map_pullback_adj CategoryTheory.Over.mapPullbackAdj
+-/
 
+#print CategoryTheory.Over.pullbackId /-
 /-- pullback (𝟙 A) : over A ⥤ over A is the identity functor. -/
 def pullbackId {A : C} : pullback (𝟙 A) ≅ 𝟭 _ :=
   Adjunction.rightAdjointUniq (mapPullbackAdj _) (Adjunction.id.ofNatIsoLeft Over.mapId.symm)
 #align category_theory.over.pullback_id CategoryTheory.Over.pullbackId
+-/
 
+#print CategoryTheory.Over.pullbackComp /-
 /-- pullback commutes with composition (up to natural isomorphism). -/
 def pullbackComp {X Y Z : C} (f : X ⟶ Y) (g : Y ⟶ Z) : pullback (f ≫ g) ≅ pullback g ⋙ pullback f :=
   Adjunction.rightAdjointUniq (mapPullbackAdj _)
     (((mapPullbackAdj _).comp (mapPullbackAdj _)).ofNatIsoLeft (Over.mapComp _ _).symm)
 #align category_theory.over.pullback_comp CategoryTheory.Over.pullbackComp
+-/
 
+#print CategoryTheory.Over.pullbackIsRightAdjoint /-
 instance pullbackIsRightAdjoint {A B : C} (f : A ⟶ B) : IsRightAdjoint (pullback f) :=
   ⟨_, mapPullbackAdj f⟩
 #align category_theory.over.pullback_is_right_adjoint CategoryTheory.Over.pullbackIsRightAdjoint
+-/
 
 end
 
@@ -135,27 +153,35 @@ end CategoryTheory.Over
 
 namespace CategoryTheory.Under
 
+#print CategoryTheory.Under.hasLimit_of_hasLimit_comp_forget /-
 instance hasLimit_of_hasLimit_comp_forget (F : J ⥤ Under X) [i : HasLimit (F ⋙ forget X)] :
     HasLimit F :=
   @StructuredArrow.hasLimit _ _ _ _ i _
 #align category_theory.under.has_limit_of_has_limit_comp_forget CategoryTheory.Under.hasLimit_of_hasLimit_comp_forget
+-/
 
 instance [HasLimitsOfShape J C] : HasLimitsOfShape J (Under X) where
 
 instance [HasLimits C] : HasLimits (Under X) :=
   ⟨inferInstance⟩
 
+#print CategoryTheory.Under.mono_right_of_mono /-
 theorem mono_right_of_mono [HasPullbacks C] {f g : Under X} (h : f ⟶ g) [Mono h] : Mono h.right :=
   StructuredArrow.mono_right_of_mono _
 #align category_theory.under.mono_right_of_mono CategoryTheory.Under.mono_right_of_mono
+-/
 
+#print CategoryTheory.Under.mono_iff_mono_right /-
 theorem mono_iff_mono_right [HasPullbacks C] {f g : Under X} (h : f ⟶ g) : Mono h ↔ Mono h.right :=
   StructuredArrow.mono_iff_mono_right _
 #align category_theory.under.mono_iff_mono_right CategoryTheory.Under.mono_iff_mono_right
+-/
 
+#print CategoryTheory.Under.createsLimits /-
 instance createsLimits : CreatesLimits (forget X) :=
   StructuredArrow.createsLimits
 #align category_theory.under.creates_limits CategoryTheory.Under.createsLimits
+-/
 
 -- We can automatically infer that the forgetful functor preserves and reflects limits.
 example [HasLimits C] : PreservesLimits (forget X) :=
@@ -168,6 +194,7 @@ section
 
 variable [HasPushouts C]
 
+#print CategoryTheory.Under.pushout /-
 /-- When `C` has pushouts, a morphism `f : X ⟶ Y` induces a functor `under X ⥤ under Y`,
 by pushing a morphism forward along `f`. -/
 @[simps]
@@ -178,6 +205,7 @@ def pushout {X Y : C} (f : X ⟶ Y) : Under X ⥤ Under Y
     Under.homMk (pushout.desc (k.right ≫ pushout.inl) pushout.inr (by simp [← pushout.condition]))
       (by tidy)
 #align category_theory.under.pushout CategoryTheory.Under.pushout
+-/
 
 end

3e0dd193

bump to nightly-2023-02-27-08

mathlib commit https://github.com/leanprover-community/mathlib/commit/eb0cb4511aaef0da2462207b67358a0e1fe1e2ee

91d8c210

Diff

@@ -44,10 +44,10 @@ variable {X : C}
 
 namespace CategoryTheory.Over
 
-instance hasColimitOfHasColimitCompForget (F : J ⥤ Over X) [i : HasColimit (F ⋙ forget X)] :
+instance hasColimit_of_hasColimit_comp_forget (F : J ⥤ Over X) [i : HasColimit (F ⋙ forget X)] :
     HasColimit F :=
   @CostructuredArrow.hasColimit _ _ _ _ i _
-#align category_theory.over.has_colimit_of_has_colimit_comp_forget CategoryTheory.Over.hasColimitOfHasColimitCompForget
+#align category_theory.over.has_colimit_of_has_colimit_comp_forget CategoryTheory.Over.hasColimit_of_hasColimit_comp_forget
 
 instance [HasColimitsOfShape J C] : HasColimitsOfShape J (Over X) where
 
@@ -135,10 +135,10 @@ end CategoryTheory.Over
 
 namespace CategoryTheory.Under
 
-instance hasLimitOfHasLimitCompForget (F : J ⥤ Under X) [i : HasLimit (F ⋙ forget X)] :
+instance hasLimit_of_hasLimit_comp_forget (F : J ⥤ Under X) [i : HasLimit (F ⋙ forget X)] :
     HasLimit F :=
   @StructuredArrow.hasLimit _ _ _ _ i _
-#align category_theory.under.has_limit_of_has_limit_comp_forget CategoryTheory.Under.hasLimitOfHasLimitCompForget
+#align category_theory.under.has_limit_of_has_limit_comp_forget CategoryTheory.Under.hasLimit_of_hasLimit_comp_forget
 
 instance [HasLimitsOfShape J C] : HasLimitsOfShape J (Under X) where

3e0dd193

bump to nightly-2023-02-21-16

mathlib commit https://github.com/leanprover-community/mathlib/commit/bd9851ca476957ea4549eb19b40e7b5ade9428cc

1107b979

Changes in mathlib4

mathlib3

mathlib4

3e0dd193

feat: cocones lift to the over category (#11488)

5f5e83b0

Diff

@@ -6,6 +6,7 @@ Authors: Johan Commelin, Reid Barton, Bhavik Mehta
 import Mathlib.CategoryTheory.Adjunction.Opposites
 import Mathlib.CategoryTheory.Comma.Over
 import Mathlib.CategoryTheory.Limits.Comma
+import Mathlib.CategoryTheory.Limits.ConeCategory
 import Mathlib.CategoryTheory.Limits.Creates
 import Mathlib.CategoryTheory.Limits.Preserves.Basic
 import Mathlib.CategoryTheory.Limits.Shapes.Pullbacks
@@ -68,6 +69,24 @@ theorem epi_iff_epi_left [HasPushouts C] {f g : Over X} (h : f ⟶ g) : Epi h 
   CostructuredArrow.epi_iff_epi_left _
 #align category_theory.over.epi_iff_epi_left CategoryTheory.Over.epi_iff_epi_left
 
+instance createsColimitsOfSizeMapCompForget {Y : C} (f : X ⟶ Y) :
+    CreatesColimitsOfSize.{w, w'} (map f ⋙ forget Y) :=
+  show CreatesColimitsOfSize.{w, w'} (forget X) from inferInstance
+
+instance preservesColimitsOfSizeMap [HasColimitsOfSize.{w, w'} C] {Y : C} (f : X ⟶ Y) :
+    PreservesColimitsOfSize.{w, w'} (map f) :=
+  preservesColimitsOfReflectsOfPreserves (map f) (forget Y)
+
+/-- If `c` is a colimit cocone, then so is the cocone `c.toOver` with cocone point `𝟙 c.pt`. -/
+def isColimitToOver {F : J ⥤ C} {c : Cocone F} (hc : IsColimit c) : IsColimit c.toOver :=
+  isColimitOfReflects (forget c.pt) <| IsColimit.equivIsoColimit c.mapCoconeToOver.symm hc
+
+/-- If `F` has a colimit, then the cocone `colimit.toOver F` with cocone point `𝟙 (colimit F)` is
+    also a colimit cocone. -/
+def _root_.CategoryTheory.Limits.colimit.isColimitToOver (F : J ⥤ C) [HasColimit F] :
+    IsColimit (colimit.toOver F) :=
+  Over.isColimitToOver (colimit.isColimit F)
+
 section
 
 variable [HasPullbacks C]
@@ -112,7 +131,7 @@ def mapPullbackAdj {A B : C} (f : A ⟶ B) : Over.map f ⊣ pullback f :=
       }
 #align category_theory.over.map_pullback_adj CategoryTheory.Over.mapPullbackAdj
 
-/-- pullback (𝟙 A) : over A ⥤ over A is the identity functor. -/
+/-- pullback (𝟙 A) : Over A ⥤ Over A is the identity functor. -/
 def pullbackId {A : C} : pullback (𝟙 A) ≅ 𝟭 _ :=
   Adjunction.rightAdjointUniq (mapPullbackAdj _) (Adjunction.id.ofNatIsoLeft (Over.mapId A).symm)
 #align category_theory.over.pullback_id CategoryTheory.Over.pullbackId
@@ -162,6 +181,24 @@ example [HasLimits C] : PreservesLimits (forget X) :=
 example : ReflectsLimits (forget X) :=
   inferInstance
 
+instance createLimitsOfSizeMapCompForget {Y : C} (f : X ⟶ Y) :
+    CreatesLimitsOfSize.{w, w'} (map f ⋙ forget X) :=
+  show CreatesLimitsOfSize.{w, w'} (forget Y) from inferInstance
+
+instance preservesLimitsOfSizeMap [HasLimitsOfSize.{w, w'} C] {Y : C} (f : X ⟶ Y) :
+    PreservesLimitsOfSize.{w, w'} (map f) :=
+  preservesLimitsOfReflectsOfPreserves (map f) (forget X)
+
+/-- If `c` is a limit cone, then so is the cone `c.toUnder` with cone point `𝟙 c.pt`. -/
+def isLimitToUnder {F : J ⥤ C} {c : Cone F} (hc : IsLimit c) : IsLimit c.toUnder :=
+  isLimitOfReflects (forget c.pt) (IsLimit.equivIsoLimit c.mapConeToUnder.symm hc)
+
+/-- If `F` has a limit, then the cone `limit.toUnder F` with cone point `𝟙 (limit F)` is
+    also a limit cone. -/
+def _root_.CategoryTheory.Limits.limit.isLimitToOver (F : J ⥤ C) [HasLimit F] :
+    IsLimit (limit.toUnder F) :=
+  Under.isLimitToUnder (limit.isLimit F)
+
 section
 
 variable [HasPushouts C]

3e0dd193

chore(*): remove empty lines between variable statements (#11418)

Empty lines were removed by executing the following Python script twice

import os
import re


# Loop through each file in the repository
for dir_path, dirs, files in os.walk('.'):
  for filename in files:
    if filename.endswith('.lean'):
      file_path = os.path.join(dir_path, filename)

      # Open the file and read its contents
      with open(file_path, 'r') as file:
        content = file.read()

      # Use a regular expression to replace sequences of "variable" lines separated by empty lines
      # with sequences without empty lines
      modified_content = re.sub(r'(variable.*\n)\n(variable(?! .* in))', r'\1\2', content)

      # Write the modified content back to the file
      with open(file_path, 'w') as file:
        file.write(modified_content)

75c86f04

Diff

@@ -34,9 +34,7 @@ universe w' w v u
 open CategoryTheory CategoryTheory.Limits
 
 variable {J : Type w} [Category.{w'} J]
-
 variable {C : Type u} [Category.{v} C]
-
 variable {X : C}
 
 namespace CategoryTheory.Over

3e0dd193

refactor: create folder CategoryTheory/Comma (#10108)

38cd7278

Diff

@@ -3,12 +3,12 @@ Copyright (c) 2018 Johan Commelin. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Johan Commelin, Reid Barton, Bhavik Mehta
 -/
-import Mathlib.CategoryTheory.Over
 import Mathlib.CategoryTheory.Adjunction.Opposites
+import Mathlib.CategoryTheory.Comma.Over
+import Mathlib.CategoryTheory.Limits.Comma
+import Mathlib.CategoryTheory.Limits.Creates
 import Mathlib.CategoryTheory.Limits.Preserves.Basic
 import Mathlib.CategoryTheory.Limits.Shapes.Pullbacks
-import Mathlib.CategoryTheory.Limits.Creates
-import Mathlib.CategoryTheory.Limits.Comma
 
 #align_import category_theory.limits.over from "leanprover-community/mathlib"@"3e0dd193514c9380edc69f1da92e80c02713c41d"

3e0dd193

refactor: replace some [@foo](https://github.com/foo) _ _ _ _ _ ... by named arguments (#8702)

Using Lean4's named arguments, we manage to remove a few hard-to-read explicit function calls [@foo](https://github.com/foo) _ _ _ _ _ ... which used to be necessary in Lean3.

Occasionally, this results in slightly longer code. The benefit of named arguments is readability, as well as to reduce the brittleness of the code when the argument order is changed.

Co-authored-by: Michael Rothgang <rothgami@math.hu-berlin.de>

df634f2a

Diff

@@ -43,7 +43,7 @@ namespace CategoryTheory.Over
 
 instance hasColimit_of_hasColimit_comp_forget (F : J ⥤ Over X) [i : HasColimit (F ⋙ forget X)] :
     HasColimit F :=
-  @CostructuredArrow.hasColimit _ _ _ _ _ _ _ _ _ i _
+  CostructuredArrow.hasColimit (i₁ := i)
 #align category_theory.over.has_colimit_of_has_colimit_comp_forget CategoryTheory.Over.hasColimit_of_hasColimit_comp_forget
 
 instance [HasColimitsOfShape J C] : HasColimitsOfShape J (Over X) where
@@ -137,7 +137,7 @@ namespace CategoryTheory.Under
 
 instance hasLimit_of_hasLimit_comp_forget (F : J ⥤ Under X) [i : HasLimit (F ⋙ forget X)] :
     HasLimit F :=
-  @StructuredArrow.hasLimit _ _ _ _ _ _ _ _ _ i _
+  StructuredArrow.hasLimit (i₁ := i)
 #align category_theory.under.has_limit_of_has_limit_comp_forget CategoryTheory.Under.hasLimit_of_hasLimit_comp_forget
 
 instance [HasLimitsOfShape J C] : HasLimitsOfShape J (Under X) where

3e0dd193

feat(CategoryTheory/Sites): internal hom of (pre)sheaves (#8622)

In this PR, we define a presheaf presheafHom F G when F and G are presheaves Cᵒᵖ ⥤ A and show that it is a sheaf when G is a sheaf (for a certain Grothendieck topology on C).

Co-authored-by: Joël Riou <37772949+joelriou@users.noreply.github.com>

c28500a0

Diff

@@ -116,7 +116,7 @@ def mapPullbackAdj {A B : C} (f : A ⟶ B) : Over.map f ⊣ pullback f :=
 
 /-- pullback (𝟙 A) : over A ⥤ over A is the identity functor. -/
 def pullbackId {A : C} : pullback (𝟙 A) ≅ 𝟭 _ :=
-  Adjunction.rightAdjointUniq (mapPullbackAdj _) (Adjunction.id.ofNatIsoLeft Over.mapId.symm)
+  Adjunction.rightAdjointUniq (mapPullbackAdj _) (Adjunction.id.ofNatIsoLeft (Over.mapId A).symm)
 #align category_theory.over.pullback_id CategoryTheory.Over.pullbackId
 
 /-- pullback commutes with composition (up to natural isomorphism). -/

3e0dd193

Revert "chore: revert #7703 (#7710)"

This reverts commit f3695eb2.

ab56fa28

Diff

@@ -108,7 +108,10 @@ def mapPullbackAdj {A B : C} (f : A ⟶ B) : Over.map f ⊣ pullback f :=
               simp only [limit.lift_π, PullbackCone.mk_pt, PullbackCone.mk_π_app]
             · dsimp
               simp only [limit.lift_π, PullbackCone.mk_pt, PullbackCone.mk_π_app, ← Over.w Y ]
-              rfl } }
+              rfl }
+      -- This used to be automatic before leanprover/lean4#2644
+      homEquiv_naturality_right := by intros; dsimp; congr 1; aesop_cat
+      }
 #align category_theory.over.map_pullback_adj CategoryTheory.Over.mapPullbackAdj
 
 /-- pullback (𝟙 A) : over A ⥤ over A is the identity functor. -/

3e0dd193

chore: revert #7703 (#7710)

This reverts commit 26eb2b0a.

f3695eb2

Diff

@@ -108,10 +108,7 @@ def mapPullbackAdj {A B : C} (f : A ⟶ B) : Over.map f ⊣ pullback f :=
               simp only [limit.lift_π, PullbackCone.mk_pt, PullbackCone.mk_π_app]
             · dsimp
               simp only [limit.lift_π, PullbackCone.mk_pt, PullbackCone.mk_π_app, ← Over.w Y ]
-              rfl }
-      -- This used to be automatic before leanprover/lean4#2644
-      homEquiv_naturality_right := by intros; dsimp; congr 1; aesop_cat
-      }
+              rfl } }
 #align category_theory.over.map_pullback_adj CategoryTheory.Over.mapPullbackAdj
 
 /-- pullback (𝟙 A) : over A ⥤ over A is the identity functor. -/

3e0dd193

chore: bump toolchain to v4.2.0-rc2 (#7703)

This includes all the changes from #7606.

Co-authored-by: Scott Morrison <scott.morrison@gmail.com>

26eb2b0a

Diff

@@ -108,7 +108,10 @@ def mapPullbackAdj {A B : C} (f : A ⟶ B) : Over.map f ⊣ pullback f :=
               simp only [limit.lift_π, PullbackCone.mk_pt, PullbackCone.mk_π_app]
             · dsimp
               simp only [limit.lift_π, PullbackCone.mk_pt, PullbackCone.mk_π_app, ← Over.w Y ]
-              rfl } }
+              rfl }
+      -- This used to be automatic before leanprover/lean4#2644
+      homEquiv_naturality_right := by intros; dsimp; congr 1; aesop_cat
+      }
 #align category_theory.over.map_pullback_adj CategoryTheory.Over.mapPullbackAdj
 
 /-- pullback (𝟙 A) : over A ⥤ over A is the identity functor. -/

3e0dd193

refactor: move morphisms in StructuredArrow to a lower universe (#6397)

This PR changes the definition

abbrev fromPUnit (X : C) : Discrete PUnit.{v + 1} ⥤ C :=
  (Functor.const _).obj X

abbrev fromPUnit (X : C) : Discrete PUnit.{w + 1} ⥤ C :=
  (Functor.const _).obj X

and then redefines

def StructuredArrow (S : D) (T : C ⥤ D) :=
  Comma (Functor.fromPUnit S) T

def StructuredArrow (S : D) (T : C ⥤ D) :=
  Comma (Functor.fromPUnit.{0} S) T

The effect of this is that given {C : Type u₁} [Category.{v₁} C] {D : Type u₂} [Category.{v₂} D] (S : D) (T : C ⥤ D), the morphisms of StructuredArrow S T no longer live in max v₁ v₂, but in v₁, as they should. Thus, this PR is basically a better version of #6388.

My guess for why we used to have the larger universe is that back in the day, the universes for limits were much more restricted, so stating the results of Limits/Comma.lean was not possible if the morphisms of StructuredArrow live in v₁. Luckily, by now it is possible to state everything correctly, and this PR adjusts Limits/Comma.lean and Limits/Over.lean accordingly.

7499ee49

Diff

@@ -29,11 +29,11 @@ TODO: If `C` has binary products, then `forget X : Over X ⥤ C` has a right adj
 noncomputable section
 
 -- morphism levels before object levels. See note [category_theory universes].
-universe v u
+universe w' w v u
 
 open CategoryTheory CategoryTheory.Limits
 
-variable {J : Type v} [SmallCategory J]
+variable {J : Type w} [Category.{w'} J]
 
 variable {C : Type u} [Category.{v} C]
 
@@ -51,9 +51,9 @@ instance [HasColimitsOfShape J C] : HasColimitsOfShape J (Over X) where
 instance [HasColimits C] : HasColimits (Over X) :=
   ⟨inferInstance⟩
 
-instance createsColimits : CreatesColimits (forget X) :=
-  CostructuredArrow.createsColimits
-#align category_theory.over.creates_colimits CategoryTheory.Over.createsColimits
+instance createsColimitsOfSize : CreatesColimitsOfSize.{w, w'} (forget X) :=
+  CostructuredArrow.createsColimitsOfSize
+#align category_theory.over.creates_colimits CategoryTheory.Over.createsColimitsOfSize
 
 -- We can automatically infer that the forgetful functor preserves and reflects colimits.
 example [HasColimits C] : PreservesColimits (forget X) :=
@@ -150,9 +150,9 @@ theorem mono_iff_mono_right [HasPullbacks C] {f g : Under X} (h : f ⟶ g) : Mon
   StructuredArrow.mono_iff_mono_right _
 #align category_theory.under.mono_iff_mono_right CategoryTheory.Under.mono_iff_mono_right
 
-instance createsLimits : CreatesLimits (forget X) :=
-  StructuredArrow.createsLimits
-#align category_theory.under.creates_limits CategoryTheory.Under.createsLimits
+instance createsLimitsOfSize : CreatesLimitsOfSize.{w, w'} (forget X) :=
+  StructuredArrow.createsLimitsOfSize
+#align category_theory.under.creates_limits CategoryTheory.Under.createsLimitsOfSize
 
 -- We can automatically infer that the forgetful functor preserves and reflects limits.
 example [HasLimits C] : PreservesLimits (forget X) :=

3e0dd193

chore: script to replace headers with #align_import statements (#5979)

depends on: #5966

Co-authored-by: Eric Wieser <wieser.eric@gmail.com> Co-authored-by: Scott Morrison <scott.morrison@gmail.com>

89aa3a3b

Diff

@@ -2,11 +2,6 @@
 Copyright (c) 2018 Johan Commelin. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Johan Commelin, Reid Barton, Bhavik Mehta
-
-! This file was ported from Lean 3 source module category_theory.limits.over
-! leanprover-community/mathlib commit 3e0dd193514c9380edc69f1da92e80c02713c41d
-! Please do not edit these lines, except to modify the commit id
-! if you have ported upstream changes.
 -/
 import Mathlib.CategoryTheory.Over
 import Mathlib.CategoryTheory.Adjunction.Opposites
@@ -15,6 +10,8 @@ import Mathlib.CategoryTheory.Limits.Shapes.Pullbacks
 import Mathlib.CategoryTheory.Limits.Creates
 import Mathlib.CategoryTheory.Limits.Comma
 
+#align_import category_theory.limits.over from "leanprover-community/mathlib"@"3e0dd193514c9380edc69f1da92e80c02713c41d"
+
 /-!
 # Limits and colimits in the over and under categories

3e0dd193

chore: fix focusing dots (#5708)

This PR is the result of running

find . -type f -name "*.lean" -exec sed -i -E 's/^( +)\. /\1· /' {} \;
find . -type f -name "*.lean" -exec sed -i -E 'N;s/^( +·)\n +(.*)$/\1 \2/;P;D' {} \;

which firstly replaces . focusing dots with · and secondly removes isolated instances of such dots, unifying them with the following line. A new rule is placed in the style linter to verify this.

cb02d09e

Diff

@@ -107,9 +107,9 @@ def mapPullbackAdj {A B : C} (f : A ⟶ B) : Over.map f ⊣ pullback f :=
             -- TODO: It would be nice to replace the next two lines with just `ext`.
             apply OverMorphism.ext
             apply pullback.hom_ext
-            . dsimp
+            · dsimp
               simp only [limit.lift_π, PullbackCone.mk_pt, PullbackCone.mk_π_app]
-            . dsimp
+            · dsimp
               simp only [limit.lift_π, PullbackCone.mk_pt, PullbackCone.mk_π_app, ← Over.w Y ]
               rfl } }
 #align category_theory.over.map_pullback_adj CategoryTheory.Over.mapPullbackAdj

3e0dd193

feat: more consistent use of ext, and updating porting notes. (#5242)

Co-authored-by: Scott Morrison <scott.morrison@anu.edu.au>

dbae2f17

Diff

@@ -104,6 +104,7 @@ def mapPullbackAdj {A B : C} (f : A ⟶ B) : Over.map f ⊣ pullback f :=
             dsimp
             simp
           right_inv := fun Y => by
+            -- TODO: It would be nice to replace the next two lines with just `ext`.
             apply OverMorphism.ext
             apply pullback.hom_ext
             . dsimp

3e0dd193

chore: review of automation in category theory (#4793)

Clean up of automation in the category theory library. Leaving out unnecessary proof steps, or fields done by aesop_cat, and making more use of available autoparameters.

Co-authored-by: Scott Morrison <scott.morrison@anu.edu.au>

5b958613

Diff

@@ -86,7 +86,6 @@ def pullback {X Y : C} (f : X ⟶ Y) : Over Y ⥤ Over X where
   obj g := Over.mk (pullback.snd : CategoryTheory.Limits.pullback g.hom f ⟶ X)
   map := fun g {h} {k} =>
     Over.homMk (pullback.lift (pullback.fst ≫ k.left) pullback.snd (by simp [pullback.condition]))
-      (by aesop_cat)
 #align category_theory.over.pullback CategoryTheory.Over.pullback
 
 /-- `Over.map f` is left adjoint to `Over.pullback f`. -/
@@ -175,7 +174,6 @@ def pushout {X Y : C} (f : X ⟶ Y) : Under X ⥤ Under Y where
   obj g := Under.mk (pushout.inr : Y ⟶ CategoryTheory.Limits.pushout g.hom f)
   map := fun g {h} {k} =>
     Under.homMk (pushout.desc (k.right ≫ pushout.inl) pushout.inr (by simp [← pushout.condition]))
-      (by aesop_cat)
 #align category_theory.under.pushout CategoryTheory.Under.pushout
 
 end

3e0dd193

chore: tidy various files (#3474)

4fe63cb5

Diff

@@ -18,22 +18,22 @@ import Mathlib.CategoryTheory.Limits.Comma
 /-!
 # Limits and colimits in the over and under categories
 
-Show that the forgetful functor `forget X : over X ⥤ C` creates colimits, and hence `over X` has
-any colimits that `C` has (as well as the dual that `forget X : under X ⟶ C` creates limits).
+Show that the forgetful functor `forget X : Over X ⥤ C` creates colimits, and hence `Over X` has
+any colimits that `C` has (as well as the dual that `forget X : Under X ⟶ C` creates limits).
 
-Note that the folder `category_theory.limits.shapes.constructions.over` further shows that
-`forget X : over X ⥤ C` creates connected limits (so `over X` has connected limits), and that
-`over X` has `J`-indexed products if `C` has `J`-indexed wide pullbacks.
+Note that the folder `CategoryTheory.Limits.Shapes.Constructions.Over` further shows that
+`forget X : Over X ⥤ C` creates connected limits (so `Over X` has connected limits), and that
+`Over X` has `J`-indexed products if `C` has `J`-indexed wide pullbacks.
 
-TODO: If `C` has binary products, then `forget X : over X ⥤ C` has a right adjoint.
+TODO: If `C` has binary products, then `forget X : Over X ⥤ C` has a right adjoint.
 -/
 
 
 noncomputable section
 
+-- morphism levels before object levels. See note [category_theory universes].
 universe v u
 
--- morphism levels before object levels. See note [category_theory universes].
 open CategoryTheory CategoryTheory.Limits
 
 variable {J : Type v} [SmallCategory J]
@@ -79,7 +79,7 @@ variable [HasPullbacks C]
 
 open Tactic
 
-/-- When `C` has pullbacks, a morphism `f : X ⟶ Y` induces a functor `over Y ⥤ over X`,
+/-- When `C` has pullbacks, a morphism `f : X ⟶ Y` induces a functor `Over Y ⥤ Over X`,
 by pulling back a morphism along `f`. -/
 @[simps]
 def pullback {X Y : C} (f : X ⟶ Y) : Over Y ⥤ Over X where
@@ -89,11 +89,10 @@ def pullback {X Y : C} (f : X ⟶ Y) : Over Y ⥤ Over X where
       (by aesop_cat)
 #align category_theory.over.pullback CategoryTheory.Over.pullback
 
-/-- `over.map f` is left adjoint to `over.pullback f`. -/
+/-- `Over.map f` is left adjoint to `Over.pullback f`. -/
 def mapPullbackAdj {A B : C} (f : A ⟶ B) : Over.map f ⊣ pullback f :=
   Adjunction.mkOfHomEquiv
-    {
-      homEquiv := fun g h =>
+    { homEquiv := fun g h =>
         { toFun := fun X =>
             Over.homMk (pullback.lift X.left g.hom (Over.w X)) (pullback.lift_snd _ _ _)
           invFun := fun Y => by
@@ -169,7 +168,7 @@ section
 
 variable [HasPushouts C]
 
-/-- When `C` has pushouts, a morphism `f : X ⟶ Y` induces a functor `under X ⥤ under Y`,
+/-- When `C` has pushouts, a morphism `f : X ⟶ Y` induces a functor `Under X ⥤ Under Y`,
 by pushing a morphism forward along `f`. -/
 @[simps]
 def pushout {X Y : C} (f : X ⟶ Y) : Under X ⥤ Under Y where

3e0dd193

feat: port CategoryTheory.Limits.Over (#3172)

Co-authored-by: Joël Riou <joel.riou@universite-paris-saclay.fr>

71438f76

`category_theory.limits.over` ⟷ `Mathlib.CategoryTheory.Limits.Over`

Changes since the initial port

Changes in mathlib3

Changes in mathlib3port

Changes in mathlib4

Dependencies 117

category_theory.limits.over ⟷ Mathlib.CategoryTheory.Limits.Over

Changes since the initial port

Changes in mathlib3

Changes in mathlib3port

Changes in mathlib4

Dependencies 117

`category_theory.limits.over` ⟷ `Mathlib.CategoryTheory.Limits.Over`