Documentation

Mathlib.Algebra.Category.ModuleCat.Images

The category of R-modules has images. #

Note that we don't need to register any of the constructions here as instances, because we get them from the fact that ModuleCat R is an abelian category.

theorem Subtype.ext_val_iff {α : Sort u_1} {p : αProp} {a1 a2 : { x : α // p x }} :
a1 = a2 a1 = a2
def ModuleCat.image {R : Type u} [Ring R] {G H : ModuleCat R} (f : G H) :

The image of a morphism in ModuleCat R is just the bundling of LinearMap.range f

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def ModuleCat.image.ι {R : Type u} [Ring R] {G H : ModuleCat R} (f : G H) :

The inclusion of image f into the target

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instance ModuleCat.instMonoι {R : Type u} [Ring R] {G H : ModuleCat R} (f : G H) :
def ModuleCat.factorThruImage {R : Type u} [Ring R] {G H : ModuleCat R} (f : G H) :

The corestriction map to the image

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noncomputable def ModuleCat.image.lift {R : Type u} [Ring R] {G H : ModuleCat R} {f : G H} (F' : CategoryTheory.Limits.MonoFactorisation f) :
image f F'.I

The universal property for the image factorisation

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  • One or more equations did not get rendered due to their size.

The factorisation of any morphism in ModuleCat R through a mono.

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noncomputable def ModuleCat.isImage {R : Type u} [Ring R] {G H : ModuleCat R} (f : G H) :

The factorisation of any morphism in ModuleCat R through a mono has the universal property of the image.

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noncomputable def ModuleCat.imageIsoRange {R : Type u} [Ring R] {G H : ModuleCat R} (f : G H) :

The categorical image of a morphism in ModuleCat R agrees with the linear algebraic range.

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