Morphisms of localizers #
A morphism of localizers consists of a functor F : C₁ ⥤ C₂ between
two categories equipped with morphism properties W₁ and W₂ such
that F sends morphisms in W₁ to morphisms in W₂.
If Φ : LocalizerMorphism W₁ W₂, and that L₁ : C₁ ⥤ D₁ and L₂ : C₂ ⥤ D₂
are localization functors for W₁ and W₂, the induced functor D₁ ⥤ D₂
is denoted Φ.localizedFunctor L₁ L₂; we introduce the condition
Φ.IsLocalizedEquivalence which expresses that this functor is an equivalence
of categories. This condition is independent of the choice of the
localized categories.
References #
If W₁ : MorphismProperty C₁ and W₂ : MorphismProperty C₂, a LocalizerMorphism W₁ W₂
is the datum of a functor C₁ ⥤ C₂ which sends morphisms in W₁ to morphisms in W₂
- functor : Functor C₁ C₂
a functor between the two categories
the functor is compatible with the
MorphismProperty
Instances For
Constructor for localizer morphisms given by a functor F : C₁ ⥤ C₂
under the stronger assumption that the classes of morphisms W₁ and W₂
satisfy W₁ = W₂.inverseImage F.
Equations
- CategoryTheory.LocalizerMorphism.ofEq hW = { functor := F, map := ⋯ }
Instances For
The identity functor as a morphism of localizers.
Equations
- CategoryTheory.LocalizerMorphism.id W₁ = { functor := CategoryTheory.Functor.id C₁, map := ⋯ }
Instances For
The composition of two localizers morphisms.
Instances For
The opposite localizer morphism LocalizerMorphism W₁.op W₂.op deduced
from Φ : LocalizerMorphism W₁ W₂.
Instances For
When Φ : LocalizerMorphism W₁ W₂ and that L₁ and L₂ are localization functors
for W₁ and W₂, then Φ.localizedFunctor L₁ L₂ is the induced functor on the
localized categories.
Equations
- Φ.localizedFunctor L₁ L₂ = CategoryTheory.Localization.lift (Φ.functor.comp L₂) ⋯ L₁
Instances For
Equations
- Φ.liftingLocalizedFunctor L₁ L₂ = { iso := CategoryTheory.LocalizerMorphism.liftingLocalizedFunctor._aux_1 Φ L₁ L₂ }
The 2-commutative square expressing that Φ.localizedFunctor L₁ L₂ lifts the
functor Φ.functor
Equations
- Φ.catCommSq L₁ L₂ = { iso := (CategoryTheory.Localization.Lifting.iso L₁ W₁ (Φ.functor.comp L₂) (Φ.localizedFunctor L₁ L₂)).symm }
If a localizer morphism induces an equivalence on some choice of localized categories, it will be so for any choice of localized categories.
Condition that a LocalizerMorphism induces an equivalence on the localized categories
- isEquivalence : (Φ.localizedFunctor W₁.Q W₂.Q).IsEquivalence
the induced functor on the constructed localized categories is an equivalence
Instances
If a LocalizerMorphism is a localized equivalence, then any compatible functor
between the localized categories is an equivalence.
If a LocalizerMorphism is a localized equivalence, then the induced functor on
the localized categories is an equivalence
When Φ : LocalizerMorphism W₁ W₂, if the composition Φ.functor ⋙ L₂ is a
localization functor for W₁, then Φ is a localized equivalence.
When the underlying functor Φ.functor of Φ : LocalizerMorphism W₁ W₂ is
an equivalence of categories and that W₁ and W₂ essentially correspond to each
other via this equivalence, then Φ is a localized equivalence.
Condition that a LocalizerMorphism induces a fully faithful functor
on the localized categories.
- nonempty_fullyFaithful : Nonempty (Φ.localizedFunctor W₁.Q W₂.Q).FullyFaithful
the induced functor on the constructed localized categories is fully faithful
Instances
If a LocalizerMorphism becomes a fully faithful after localization, then any compatible
functor between the localized categories is fully faithful.
Equations
- Φ.fullyFaithful L₁ L₂ G = ⋯.some
Instances For
If a LocalizerMorphism becomes fully faithful after localization,
then the induced functor on the localized categories is fully faithful.
Equations
- Φ.fullyFaithfulLocalizedFunctor L₁ L₂ = Φ.fullyFaithful L₁ L₂ (Φ.localizedFunctor L₁ L₂)
Instances For
Assume that a localizer morphism Φ : LocalizerMorphism W₁ W₂ induces
a fully faithful functor on the localized categories.
If L₂ : C₂ ⥤ D₂ is a localization functor for W₂ and we have a
factorization iso : Φ.functor ⋙ L₂ ≅ L₁ ⋙ F as an essentially surjective
functor L₁ : C₁ ⥤ D₁ followed by a fully faithful functor F : D₁ ⥤ D₂,
then L₁ is a localization functor for W₁.
The localizer morphism from W₁.arrow to W₂.arrow that is induced by
Φ : LocalizerMorphism W₁ W₂.
Instances For
If Φ : LocalizerMorphism W₁ W₂, the typeclass Φ.IsInduced
says that W₂.inverseImage Φ.functor = W₁.
Instances
The inverse of a localizer morphism Φ : LocalizerMorphism W₁ W₂,
when Φ.functor is an equivalence, W₁ is induced by W₂
and W₂ respects isomorphisms.