Proposition 6.1 with dual mesh weights (for Proposition 7.5) #
residual_dual: in characteristic two, under the hypotheses of Proposition 6.1, there is a
set S of spanning rows, at most one in each periodic component, together with integer
mesh weights W_R (R ∈ S) such that the weight of the row R' minus ν of its vertex
is 1 if R' = R and 0 otherwise. This is the input of Proposition 7.5: by Lemma 7.4
these give integer ray weights dual to the residual characters.
theorem
MultiplicativeBasisDeformations.residual_dual
{k : Type u}
[Field k]
{V : Type}
[Quiver V]
[Fintype V]
[DecidableEq V]
[(x y : V) → Fintype (x ⟶ y)]
[(x y : V) → DecidableEq (x ⟶ y)]
[(x : V) → Fintype ((y : V) × (y ⟶ x))]
{Q : TranslationQuiver V}
[DecidablePred fun (x : V) => x ∈ Q.nonprojective]
[Fintype ↑Q.nonprojective]
(c : MeshCoefficients k Q)
(hQ : HasAtMostOneArrow V)
(hchar : 2 = 0)
(hfin : ∀ (x y : V), FiniteDimensional k (ScalarMeshCategory.obj c x ⟶ ScalarMeshCategory.obj c y))
(hbrick : ScalarMeshCategory.BrickHypothesis c)
:
∃ (S : ScalarMeshCategory.RowSet Q),
(∀ R ∈ S, ↑R.fst ∈ Q.periodic) ∧ (∀ R ∈ S, ∀ R' ∈ S, ↑R'.fst ∈ Q.component ↑R.fst → R = R') ∧ ScalarMeshCategory.CokerSpan c S ∧ ∀ R ∈ S, ∃ (W : MeshWalk.MeshWt Q ℤ), ∀ R' ∈ S, W.pw R'.snd - W.ν R'.fst = if R' = R then 1 else 0
Proposition 6.1 with dual mesh weights.