Magnitude conjecture

MagnitudeConjecture.CategoryTheory.ShortExactKernelTransport

Transporting the kernel of a short exact complex #

noncomputable def CategoryTheory.ShortComplex.sourceIsoKernelOfShortExactCompIso {C : Type u} [Category.{v, u} C] [Abelian C] (S : ShortComplex C) (hS : S.ShortExact) {Y : C} (g : S.X₂ ⟶ Y) (e : S.X₃ ≅ Y) (h : CategoryStruct.comp S.g e.hom = g) :
S.X₁ ≅ Limits.kernel g

If a short exact complex's second map is transported across an isomorphism of its target, its source remains a kernel of the transported map.

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