Limits in C
give colimits in Cᵒᵖ
. #
We also give special cases for (co)products, (co)equalizers, and pullbacks / pushouts.
Turn a colimit for F : J ⥤ Cᵒᵖ
into a limit for F.leftOp : Jᵒᵖ ⥤ C
.
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Turn a limit of F : J ⥤ Cᵒᵖ
into a colimit of F.leftOp : Jᵒᵖ ⥤ C
.
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Turn a colimit for F : Jᵒᵖ ⥤ C
into a limit for F.rightOp : J ⥤ Cᵒᵖ
.
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Turn a limit for F : Jᵒᵖ ⥤ C
into a colimit for F.rightOp : J ⥤ Cᵒᵖ
.
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Turn a colimit for F : Jᵒᵖ ⥤ Cᵒᵖ
into a limit for F.unop : J ⥤ C
.
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Turn a limit of F : Jᵒᵖ ⥤ Cᵒᵖ
into a colimit of F.unop : J ⥤ C
.
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Turn a colimit for F.leftOp : Jᵒᵖ ⥤ C
into a limit for F : J ⥤ Cᵒᵖ
.
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Turn a limit of F.leftOp : Jᵒᵖ ⥤ C
into a colimit of F : J ⥤ Cᵒᵖ
.
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Turn a colimit for F.rightOp : J ⥤ Cᵒᵖ
into a limit for F : Jᵒᵖ ⥤ C
.
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Turn a limit for F.rightOp : J ⥤ Cᵒᵖ
into a colimit for F : Jᵒᵖ ⥤ C
.
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Turn a colimit for F.unop : J ⥤ C
into a limit for F : Jᵒᵖ ⥤ Cᵒᵖ
.
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Turn a limit for F.unop : J ⥤ C
into a colimit for F : Jᵒᵖ ⥤ Cᵒᵖ
.
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Turn a limit for F.leftOp : Jᵒᵖ ⥤ C
into a colimit for F : J ⥤ Cᵒᵖ
.
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Turn a colimit for F.leftOp : Jᵒᵖ ⥤ C
into a limit for F : J ⥤ Cᵒᵖ
.
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Turn a limit for F.rightOp : J ⥤ Cᵒᵖ
into a colimit for F : Jᵒᵖ ⥤ C
.
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Turn a colimit for F.rightOp : J ⥤ Cᵒᵖ
into a limit for F : Jᵒᵖ ⥤ C
.
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Turn a limit for F.unop : J ⥤ C
into a colimit for F : Jᵒᵖ ⥤ Cᵒᵖ
.
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Turn a colimit for F.unop : J ⥤ C
into a limit for F : Jᵒᵖ ⥤ Cᵒᵖ
.
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Turn a limit for F : J ⥤ Cᵒᵖ
into a colimit for F.leftOp : Jᵒᵖ ⥤ C
.
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Turn a colimit for F : J ⥤ Cᵒᵖ
into a limit for F.leftOp : Jᵒᵖ ⥤ C
.
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Turn a limit for F : Jᵒᵖ ⥤ C
into a colimit for F.rightOp : J ⥤ Cᵒᵖ.
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Turn a colimit for F : Jᵒᵖ ⥤ C
into a limit for F.rightOp : J ⥤ Cᵒᵖ
.
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Turn a limit for F : Jᵒᵖ ⥤ Cᵒᵖ
into a colimit for F.unop : J ⥤ C
.
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Turn a colimit for F : Jᵒᵖ ⥤ Cᵒᵖ
into a limit for F.unop : J ⥤ C
.
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If F.leftOp : Jᵒᵖ ⥤ C
has a colimit, we can construct a limit for F : J ⥤ Cᵒᵖ
.
The limit of F.op
is the opposite of colimit F
.
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The limit of F.leftOp
is the unopposite of colimit F
.
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The limit of F.rightOp
is the opposite of colimit F
.
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The limit of F.unop
is the unopposite of colimit F
.
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If C
has colimits of shape Jᵒᵖ
, we can construct limits in Cᵒᵖ
of shape J
.
If C
has colimits, we can construct limits for Cᵒᵖ
.
If F.leftOp : Jᵒᵖ ⥤ C
has a limit, we can construct a colimit for F : J ⥤ Cᵒᵖ
.
The colimit of F.op
is the opposite of limit F
.
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The colimit of F.leftOp
is the unopposite of limit F
.
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The colimit of F.rightOp
is the opposite of limit F
.
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The colimit of F.unop
is the unopposite of limit F
.
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If C
has colimits of shape Jᵒᵖ
, we can construct limits in Cᵒᵖ
of shape J
.
If C
has limits, we can construct colimits for Cᵒᵖ
.
If C
has products indexed by X
, then Cᵒᵖ
has coproducts indexed by X
.
If C
has coproducts indexed by X
, then Cᵒᵖ
has products indexed by X
.
A Cofan
gives a Fan
in the opposite category.
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If a Cofan
is colimit, then its opposite is limit.
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The canonical isomorphism from the opposite of an abstract coproduct to the corresponding product in the opposite category.
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The canonical isomorphism from the opposite of the coproduct to the product in the opposite category.
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A Fan
gives a Cofan
in the opposite category.
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If a Fan
is limit, then its opposite is colimit.
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The canonical isomorphism from the opposite of an abstract product to the corresponding coproduct in the opposite category.
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The canonical isomorphism from the opposite of the product to the coproduct in the opposite category.
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The canonical isomorphism from the opposite of the binary product to the coproduct in the opposite category.
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The obvious map PushoutCocone f g → PullbackCone f.unop g.unop
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The obvious map PushoutCocone f.op g.op → PullbackCone f g
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The obvious map PullbackCone f g → PushoutCocone f.unop g.unop
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The obvious map PullbackCone f g → PushoutCocone f.op g.op
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If c
is a pullback cone, then c.op.unop
is isomorphic to c
.
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If c
is a pullback cone in Cᵒᵖ
, then c.unop.op
is isomorphic to c
.
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If c
is a pushout cocone, then c.op.unop
is isomorphic to c
.
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If c
is a pushout cocone in Cᵒᵖ
, then c.unop.op
is isomorphic to c
.
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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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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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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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A colimit cokernel cofork gives a limit kernel fork in the opposite category
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A colimit cokernel cofork in the opposite category gives a limit kernel fork in the original category
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A limit kernel fork gives a colimit cokernel cofork in the opposite category
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A limit kernel fork in the opposite category gives a colimit cokernel cofork in the original category