English
A δ-mediated exact sequence gives a perfect resolution in a shifted context.
Русский
Крaткая последовательность, управляемая δ, обеспечивает разрешение после сдвига.
LaTeX
$$$(F.shift n_0).shifted\ δ_1$-exactness$$
Lean4
theorem homologySequence_exact₁ : (ShortComplex.mk _ _ (F.homologySequenceδ_comp T hT _ _ h)).Exact :=
by
refine ShortComplex.exact_of_iso ?_ (F.homologySequence_exact₂ _ (inv_rot_of_distTriang _ hT) n₁)
refine ShortComplex.isoMk (-((F.shiftIso (-1) n₁ n₀ (by cutsat)).app _)) (Iso.refl _) (Iso.refl _) ?_ (by simp)
dsimp
simp only [homologySequenceδ, neg_comp, map_neg, comp_id,
F.shiftIso_hom_app_comp_shiftMap_of_add_eq_zero T.mor₃ (-1) (neg_add_cancel 1) n₀ n₁ (by cutsat)]