Uniqueness of adjoints #
This file shows that adjoints are unique up to natural isomorphism.
Main results #
Adjunction.natTransEquiv
andAdjunction.natIsoEquiv
IfF ⊣ G
andF' ⊣ G'
are adjunctions, then there are equivalences(G ⟶ G') ≃ (F' ⟶ F)
and(G ≅ G') ≃ (F' ≅ F)
. Everything else is deduced from this:Adjunction.leftAdjointUniq
: IfF
andF'
are both left adjoint toG
, then they are naturally isomorphic.Adjunction.rightAdjointUniq
: IfG
andG'
are both right adjoint toF
, then they are naturally isomorphic.
If F ⊣ G
and F' ⊣ G'
are adjunctions, then giving a natural transformation G ⟶ G'
is the
same as giving a natural transformation F' ⟶ F
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
If F ⊣ G
and F' ⊣ G'
are adjunctions, then giving a natural isomorphism G ≅ G'
is the
same as giving a natural transformation F' ≅ F
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
If F
and F'
are both left adjoint to G
, then they are naturally isomorphic.
Equations
- adj1.leftAdjointUniq adj2 = ((adj1.natIsoEquiv adj2) (CategoryTheory.Iso.refl G)).symm
Instances For
If G
and G'
are both right adjoint to F
, then they are naturally isomorphic.
Equations
- adj1.rightAdjointUniq adj2 = (adj1.natIsoEquiv adj2).symm (CategoryTheory.Iso.refl F)