k(Γ_A) is finite-dimensional #
graded-category.tex, eq. (2.15) of the proof of Proposition 2.10:
"dim C(X, Y) = ∑_n dim J^n(X, Y)/J^{n+1}(X, Y) = dim Hom_A(X, Y). It follows
from the finite radical filtration." By Proposition 2.6(3) the Hom spaces of
k(Γ_A) are the direct sums of their degree parts, which are the radical
layers; these vanish from the nilpotency index of the radical on.
instance
MultiplicativeBasisDeformations.IndSkeleton.finiteDimensional_degreePart
{k A : Type w}
[Field k]
[IsAlgClosed k]
[Ring A]
[Algebra k A]
[FiniteDimensional k A]
[IsNoetherianRing Aᵐᵒᵖ]
(S : IndSkeleton k A)
(b : S.ArrowBases)
(d : ℕ)
(x y : S.ARVertex)
:
FiniteDimensional k ↥(ScalarMeshCategory.degreePart (S.arCoefficients b) d x y)
theorem
MultiplicativeBasisDeformations.IndSkeleton.degreePart_eq_bot
{k A : Type w}
[Field k]
[IsAlgClosed k]
[Ring A]
[Algebra k A]
[FiniteDimensional k A]
[IsNoetherianRing Aᵐᵒᵖ]
(S : IndSkeleton k A)
(b : S.ArrowBases)
{N : ℕ}
(hN : ∀ (X Y : S.Ind), S.radPow N X Y = ⊥)
{d : ℕ}
(hd : N ≤ d)
(x y : S.ARVertex)
:
ScalarMeshCategory.degreePart (S.arCoefficients b) d x y = ⊥
theorem
MultiplicativeBasisDeformations.IndSkeleton.finiteDimensional_meshHom
{k A : Type w}
[Field k]
[IsAlgClosed k]
[Ring A]
[Algebra k A]
[FiniteDimensional k A]
[IsNoetherianRing Aᵐᵒᵖ]
(S : IndSkeleton k A)
(b : S.ArrowBases)
(x y : S.ARVertex)
:
The Hom spaces of k(Γ_A) are finite-dimensional.