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Mathlib.CategoryTheory.Limits.Shapes.Opposites.Pullbacks

Pullbacks and pushouts in C and Cᵒᵖ #

We construct pullbacks and pushouts in the opposite categories.

def CategoryTheory.Limits.spanOp {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} (f : X Z) (g : Y Z) :

The canonical isomorphism relating Span f.op g.op and (Cospan f g).op

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      theorem CategoryTheory.Limits.spanOp_inv_app {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} (f : X Z) (g : Y Z) (X✝ : WalkingSpan) :
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      theorem CategoryTheory.Limits.spanOp_hom_app {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} (f : X Z) (g : Y Z) (X✝ : WalkingSpan) :
      def CategoryTheory.Limits.opCospan {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} (f : X Z) (g : Y Z) :

      The canonical isomorphism relating (Cospan f g).op and Span f.op g.op

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          def CategoryTheory.Limits.cospanOp {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} (f : X Y) (g : X Z) :

          The canonical isomorphism relating Cospan f.op g.op and (Span f g).op

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              theorem CategoryTheory.Limits.cospanOp_inv_app {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} (f : X Y) (g : X Z) (X✝ : WalkingCospan) :
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              theorem CategoryTheory.Limits.cospanOp_hom_app {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} (f : X Y) (g : X Z) (X✝ : WalkingCospan) :
              def CategoryTheory.Limits.opSpan {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} (f : X Y) (g : X Z) :

              The canonical isomorphism relating (Span f g).op and Cospan f.op g.op

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                  def CategoryTheory.Limits.PushoutCocone.unop {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : Cᵒᵖ} {f : X Y} {g : X Z} (c : PushoutCocone f g) :

                  The obvious map PushoutCocone f g → PullbackCone f.unop g.unop

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                      theorem CategoryTheory.Limits.PushoutCocone.unop_pt {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : Cᵒᵖ} {f : X Y} {g : X Z} (c : PushoutCocone f g) :
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                      theorem CategoryTheory.Limits.PushoutCocone.unop_π_app {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : Cᵒᵖ} {f : X Y} {g : X Z} (c : PushoutCocone f g) (X✝ : WalkingCospan) :
                      def CategoryTheory.Limits.PushoutCocone.op {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} {f : X Y} {g : X Z} (c : PushoutCocone f g) :

                      The obvious map PushoutCocone f.op g.op → PullbackCone f g

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                          theorem CategoryTheory.Limits.PushoutCocone.op_pt {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} {f : X Y} {g : X Z} (c : PushoutCocone f g) :
                          theorem CategoryTheory.Limits.PushoutCocone.op_fst {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} {f : X Y} {g : X Z} (c : PushoutCocone f g) :
                          c.op.fst = c.inl.op
                          theorem CategoryTheory.Limits.PushoutCocone.op_snd {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} {f : X Y} {g : X Z} (c : PushoutCocone f g) :
                          c.op.snd = c.inr.op
                          def CategoryTheory.Limits.PullbackCone.unop {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : Cᵒᵖ} {f : X Z} {g : Y Z} (c : PullbackCone f g) :

                          The obvious map PullbackCone f g → PushoutCocone f.unop g.unop

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                              theorem CategoryTheory.Limits.PullbackCone.unop_ι_app {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : Cᵒᵖ} {f : X Z} {g : Y Z} (c : PullbackCone f g) (X✝ : WalkingSpan) :
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                              theorem CategoryTheory.Limits.PullbackCone.unop_pt {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : Cᵒᵖ} {f : X Z} {g : Y Z} (c : PullbackCone f g) :
                              def CategoryTheory.Limits.PullbackCone.op {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} {f : X Z} {g : Y Z} (c : PullbackCone f g) :

                              The obvious map PullbackCone f g → PushoutCocone f.op g.op

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                                  theorem CategoryTheory.Limits.PullbackCone.op_pt {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} {f : X Z} {g : Y Z} (c : PullbackCone f g) :
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                                  theorem CategoryTheory.Limits.PullbackCone.op_ι_app {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} {f : X Z} {g : Y Z} (c : PullbackCone f g) (X✝ : WalkingSpan) :
                                  theorem CategoryTheory.Limits.PullbackCone.op_inl {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} {f : X Z} {g : Y Z} (c : PullbackCone f g) :
                                  c.op.inl = c.fst.op
                                  theorem CategoryTheory.Limits.PullbackCone.op_inr {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} {f : X Z} {g : Y Z} (c : PullbackCone f g) :
                                  c.op.inr = c.snd.op
                                  def CategoryTheory.Limits.PullbackCone.opUnopIso {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} {f : X Z} {g : Y Z} (c : PullbackCone f g) :
                                  c.op.unop c

                                  If c is a pullback cone, then c.op.unop is isomorphic to c.

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                                      def CategoryTheory.Limits.PullbackCone.unopOpIso {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : Cᵒᵖ} {f : X Z} {g : Y Z} (c : PullbackCone f g) :
                                      c.unop.op c

                                      If c is a pullback cone in Cᵒᵖ, then c.unop.op is isomorphic to c.

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                                          def CategoryTheory.Limits.PushoutCocone.opUnopIso {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} {f : X Y} {g : X Z} (c : PushoutCocone f g) :
                                          c.op.unop c

                                          If c is a pushout cocone, then c.op.unop is isomorphic to c.

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                                              def CategoryTheory.Limits.PushoutCocone.unopOpIso {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : Cᵒᵖ} {f : X Y} {g : X Z} (c : PushoutCocone f g) :
                                              c.unop.op c

                                              If c is a pushout cocone in Cᵒᵖ, then c.unop.op is isomorphic to c.

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                                                  noncomputable def CategoryTheory.Limits.PushoutCocone.isColimitEquivIsLimitOp {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} {f : X Y} {g : X Z} (c : PushoutCocone f g) :

                                                  A pushout cone is a colimit cocone if and only if the corresponding pullback cone in the opposite category is a limit cone.

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                                                      A pushout cone is a colimit cocone in Cᵒᵖ if and only if the corresponding pullback cone in C is a limit cone.

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                                                          A pullback cone is a limit cone if and only if the corresponding pushout cocone in the opposite category is a colimit cocone.

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                                                              A pullback cone is a limit cone in Cᵒᵖ if and only if the corresponding pushout cocone in C is a colimit cocone.

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                                                                  noncomputable def CategoryTheory.Limits.pullbackIsoUnopPushout {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} (f : X Z) (g : Y Z) [h : HasPullback f g] [HasPushout f.op g.op] :

                                                                  The pullback of f and g in C is isomorphic to the pushout of f.op and g.op in Cᵒᵖ.

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                                                                      noncomputable def CategoryTheory.Limits.pullbackIsoOpPushout {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : Cᵒᵖ} (f : X Z) (g : Y Z) [h : HasPullback f g] [HasPushout f.unop g.unop] :

                                                                      The pullback of f and g in Cᵒᵖ is isomorphic to the pushout of f.unop and g.unop in C.

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                                                                          noncomputable def CategoryTheory.Limits.pushoutIsoUnopPullback {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : C} (f : X Z) (g : X Y) [h : HasPushout f g] [HasPullback f.op g.op] :

                                                                          The pushout of f and g in C is isomorphic to the pullback of f.op and g.op in Cᵒᵖ.

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                                                                              noncomputable def CategoryTheory.Limits.pushoutIsoOpPullback {C : Type u₁} [Category.{v₁, u₁} C] {X Y Z : Cᵒᵖ} (f : X Z) (g : X Y) [h : HasPushout f g] [HasPullback f.unop g.unop] :

                                                                              The pushout of f and g in Cᵒᵖ is isomorphic to the pullback of f.unop and g.unop in C.

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                                                                                  def CategoryTheory.CommSq.coneOp {C : Type u_1} [Category.{v_1, u_1} C] {W X Y Z : C} {f : W X} {g : W Y} {h : X Z} {i : Y Z} (p : CommSq f g h i) :

                                                                                  The pushout cocone in the opposite category associated to the cone of a commutative square identifies to the cocone of the flipped commutative square in the opposite category

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                                                                                      def CategoryTheory.CommSq.coconeOp {C : Type u_1} [Category.{v_1, u_1} C] {W X Y Z : C} {f : W X} {g : W Y} {h : X Z} {i : Y Z} (p : CommSq f g h i) :

                                                                                      The pullback cone in the opposite category associated to the cocone of a commutative square identifies to the cone of the flipped commutative square in the opposite category

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                                                                                          def CategoryTheory.CommSq.coneUnop {C : Type u_1} [Category.{v_1, u_1} C] {W X Y Z : Cᵒᵖ} {f : W X} {g : W Y} {h : X Z} {i : Y Z} (p : CommSq f g h i) :

                                                                                          The pushout cocone obtained from the pullback cone associated to a commutative square in the opposite category identifies to the cocone associated to the flipped square.

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                                                                                              def CategoryTheory.CommSq.coconeUnop {C : Type u_1} [Category.{v_1, u_1} C] {W X Y Z : Cᵒᵖ} {f : W X} {g : W Y} {h : X Z} {i : Y Z} (p : CommSq f g h i) :

                                                                                              The pullback cone obtained from the pushout cone associated to a commutative square in the opposite category identifies to the cone associated to the flipped square.

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