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2c7d975 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 | import OAI.Algebra.AuslanderReiten.Resolutions.MapResolutionExtMk
namespace OAI
noncomputable section
open CategoryTheory CategoryTheory.Abelian CategoryTheory.Limits
namespace ArExplicit.ResolutionProducts
universe u v
variable {C : Type u} [Category.{v} C] [Abelian C] [HasExt.{v} C]
variable (F : C ⥤ C) [F.Additive] [PreservesFiniteLimits F]
[PreservesFiniteColimits F] [F.PreservesProjectiveObjects]
variable {X Y : C} (P : ProjectiveResolution X) {n : ℕ}
theorem map_extMk_conjugate (a : X ⟶ F.obj X) (b : F.obj Y ⟶ Y)
(φ : ProjectiveResolution.Hom P (mapResolution F P) a)
(f : P.complex.X n ⟶ Y) (hf : P.complex.d (n+1) n ≫ f = 0)
(g : P.complex.X n ⟶ Y) (hg : P.complex.d (n+1) n ≫ g = 0)
(hgf : g = (φ.hom.f n ≫ F.map f) ≫ b) :
((Ext.mk₀ a).comp ((P.extMk f (n+1) rfl hf).mapExactFunctor F) (zero_add n)).comp
(Ext.mk₀ b) (add_zero n) =
P.extMk g (n+1) rfl hg := by
subst g
erw [map_extMk, ProjectiveResolution.mk₀_comp_extMk _ _ _ _ φ,
ProjectiveResolution.extMk_comp_mk₀]
end ArExplicit.ResolutionProducts
end
end OAI
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