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Mathlib.Algebra.Homology.HomologicalComplexBiprod

Binary biproducts of homological complexes

In this file, it is shown that if two homological complex K and L in a preadditive category are such that for all i : ι, the binary biproduct K.X i ⊞ L.X i exists, then K ⊞ L exists, and there is an isomorphism biprodXIso K L i : (K ⊞ L).X i ≅ (K.X i) ⊞ (L.X i).

noncomputable def HomologicalComplex.biprodXIso {C : Type u_1} {ι : Type u_2} [CategoryTheory.Category.{u_3, u_1} C] [CategoryTheory.Preadditive C] {c : ComplexShape ι} (K L : HomologicalComplex C c) [∀ (i : ι), CategoryTheory.Limits.HasBinaryBiproduct (K.X i) (L.X i)] (i : ι) :
(K L).X i K.X i L.X i

The canonical isomorphism (K ⊞ L).X i ≅ (K.X i) ⊞ (L.X i).

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