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Theorems · Theorem · category theory

CategoryTheory.Functor.essImage_comp_of_essSurj

∀ {C : Type u₁} {D : Type u₂} {E : Type u₃} [inst : CategoryTheory.Category.{v₁, u₁} C]
  [inst_1 : CategoryTheory.Category.{v₂, u₂} D] [inst_2 : CategoryTheory.Category.{v₃, u₃} E]
  {F : CategoryTheory.Functor C D} {G : CategoryTheory.Functor D E} [F.EssSurj], (F.comp G).essImage = G.essImage

Pre-composing by an essentially surjective functor doesn't change the essential image.

Defined in
Mathlib.CategoryTheory.EssentialImage
Cited by
3 results in Mathlib
Foundations
Depth 19 from the axioms · uses propext, Classical.choice, Quot.sound
Assumes
CategoryTheory.CategoryCategoryTheory.CategoryCategoryTheory.CategoryCategoryTheory.Functor.EssSurj

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