Decompositions into shifted standard-form representatives #
theorem
MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.standardFormGraded_shifted_exists_iso
{k A : Type u}
[Field k]
[IsAlgClosed k]
[Ring A]
[Algebra k A]
[FiniteDimensional k A]
[IsNoetherianRing Aᵐᵒᵖ]
(S : FiniteIndecomposableSkeleton k A)
(M : Graded.FiniteGradedModule.ShiftedModule)
(hM : CategoryTheory.Indecomposable M)
:
∃ (i : Fin S.n) (s : ℤ), Nonempty (M ≅ { obj := S.standardFormGradedFamily i, degree := s })
Classification also applies when an arbitrary external shift is already present.
theorem
MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.standardFormGraded_decomposition
{k A : Type u}
[Field k]
[IsAlgClosed k]
[Ring A]
[Algebra k A]
[FiniteDimensional k A]
[IsNoetherianRing Aᵐᵒᵖ]
(S : FiniteIndecomposableSkeleton k A)
(M : Graded.FiniteGradedModule.ShiftedModule)
:
∃ (n : ℕ) (i : Fin n → Fin S.n) (s : Fin n → ℤ),
Nonempty (M ≅ ⨁ fun (j : Fin n) => { obj := S.standardFormGradedFamily (i j), degree := s j })
Every graded module is a finite sum of the classified shifted vertex modules.