Compatibility of actual module coordinates with the reconstructed action #
theorem
MagnitudeConjecture.Graded.FiniteGradedModule.intervalActionMap_evaluation
{k A : Type u}
[Field k]
[Ring A]
[Algebra k A]
[FiniteDimensional k A]
(R : VectorGrading k A)
(hmul : ∀ {i j : ℤ} {a b : A}, a ∈ R.component i → b ∈ R.component j → a * b ∈ R.component (i + j))
{ι : Type}
[Fintype ι]
(e : ι → A)
(he0 : ∀ (i : ι), e i ∈ R.component 0)
(he : ∀ (i : ι), e i * e i = e i)
(m : ℕ)
(X : SupportedCategory m)
(a : A)
(y :
intervalCoordinateSpace R ⋯ e he0 (CoveringHom.restrictedLinearYoneda (principalDegreeInclusion R ⋯ e he0) X.obj) m)
(p : ι × Fin (m + 1))
:
↑((principalShiftHomEquiv R ⋯ (e p.1) ⋯ ⋯ (↑↑p.2) X.obj)
((intervalActionMap R ⋯ e he0 he (CoveringHom.restrictedLinearYoneda (principalDegreeInclusion R ⋯ e he0) X.obj) m
a)
y p)) = ∑ q : ι × Fin (m + 1), intervalCorner R e m p q a • ↑((principalShiftHomEquiv R ⋯ (e q.1) ⋯ ⋯ (↑↑q.2) X.obj) (y q))
Evaluation turns the reconstructed matrix action into the same action on coordinate vectors.
theorem
MagnitudeConjecture.Graded.FiniteGradedModule.supportedModuleCoordinateEquiv_smul
{k A : Type u}
[Field k]
[Ring A]
[Algebra k A]
[FiniteDimensional k A]
(R : VectorGrading k A)
(hmul : ∀ {i j : ℤ} {a b : A}, a ∈ R.component i → b ∈ R.component j → a * b ∈ R.component (i + j))
{ι : Type}
[Fintype ι]
(e : ι → A)
(he0 : ∀ (i : ι), e i ∈ R.component 0)
(he : ∀ (i : ι), e i * e i = e i)
(hsum : ∑ i : ι, e i = 1)
(horth : Pairwise fun (i j : ι) => e i * e j = 0)
(m : ℕ)
(X : SupportedCategory m)
(a : A)
(x : ↑X.obj.obj.module)
:
(supportedModuleCoordinateEquiv R ⋯ e he0 he hsum horth m X) (a • x) = (intervalActionMap R ⋯ e he0 he (CoveringHom.restrictedLinearYoneda (principalDegreeInclusion R ⋯ e he0) X.obj) m a)
((supportedModuleCoordinateEquiv R ⋯ e he0 he hsum horth m X) x)
The vector-space coordinate equivalence intertwines the actual algebra action with reconstruction.