Multiplicative bases

MultiplicativeBasisDeformations.Statements.FamilyCriterionWP

Propositions 7.9 and 12.8 with characters in W(P) #

prop:family-criterion and prop:polynomial-mesh-comparison, for a basic connected representation-finite algebra A in characteristic two, with the residual characters χ_i = w(p_i) − ν_{v_i} in the weight lattice L = W(P) of the universal mesh weight w (Lemma 7.4), as in the source. The rows are those of Proposition 6.1 (residual_dual), of length at least three (shorter rows carry no cokernel class); their characters are pairwise distinct and part of an integer basis of W(P) (Proposition 7.5), and have degree len p_i − 2 (rowsWP). The family statements are the generic ones of FamilyCriterionGen.lean and PolynomialMesh.lean for this weight.

theorem MultiplicativeBasisDeformations.ScalarMeshCategory.cokerSpan_filter {k : Type u_1} [Field k] {V : Type} [Quiver V] [Fintype V] [DecidableEq V] {Q : TranslationQuiver V} [(x : V) → Fintype ((y : V) × (y ⟶ x))] (c : MeshCoefficients k Q) {S : RowSet Q} (hS : CokerSpan c S) :
CokerSpan c {R : (x : ↑Q.nonprojective) × Quiver.Path ↑(Q.tau x) ↑x | R ∈ S ∧ 3 ≤ R.snd.length}

Rows of length below three carry no cokernel class.

theorem MultiplicativeBasisDeformations.IndSkeleton.rowsWP {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : IndSkeleton k A) (b : S.ArrowBases) (h2 : 2 = 0) (hbasic : IsBasicAlgebra A) (hconn : IsConnectedRing A) (v₀ : S.ARVertex) :
∃ (n : ℕ) (Rw : Fin n → (x : ↑S.arTranslationQuiver.nonprojective) × Quiver.Path ↑(S.arTranslationQuiver.tau x) ↑x) (Wu : MeshWalk.MeshWt S.arTranslationQuiver (MeshWalk.WP S.arTranslationQuiver (S.arCoefficients b) v₀ (S.arMeshData b))), MeshWalk.MeshWt.res (S.arCoefficients b) (S.arMeshData b) Wu = AddMonoidHom.id (MeshWalk.WP S.arTranslationQuiver (S.arCoefficients b) v₀ (S.arMeshData b)) ∧ Function.Injective Rw ∧ (∀ (i : Fin n), ↑(Rw i).fst ∈ S.arTranslationQuiver.periodic) ∧ (∀ (i j : Fin n), ↑(Rw j).fst ∈ S.arTranslationQuiver.component ↑(Rw i).fst → i = j) ∧ ScalarMeshCategory.CokerSpan (S.arCoefficients b) (Set.range Rw) ∧ (∀ (i : Fin n), 3 ≤ (Rw i).snd.length) ∧ (Function.Injective fun (i : Fin n) => MeshWalk.rowWt Wu (Rw i)) ∧ (∃ (κ : Type) (bL : Module.Basis κ ℤ (MeshWalk.WP S.arTranslationQuiver (S.arCoefficients b) v₀ (S.arMeshData b))) (jι : Fin n → κ), Function.Injective jι ∧ ∀ (i : Fin n), bL (jι i) = MeshWalk.rowWt Wu (Rw i)) ∧ ∀ (i : Fin n), (MeshWalk.MeshWt.res (S.arCoefficients b) (S.arMeshData b) MeshWalk.lenW) (MeshWalk.rowWt Wu (Rw i)) = ↑(Rw i).snd.length - 2

The rows of Proposition 6.1 with their characters in W(P).

noncomputable def MultiplicativeBasisDeformations.IndSkeleton.basisCoords {L : Type} [AddCommGroup L] {κ : Type} (bL : Module.Basis κ ℤ L) {n : ℕ} (jι : Fin n → κ) :
L →+ Fin n → ℤ

The coordinates of an integer basis on chosen basis vectors.

Instances For
    theorem MultiplicativeBasisDeformations.IndSkeleton.basisCoords_apply {L : Type} [AddCommGroup L] {κ : Type} (bL : Module.Basis κ ℤ L) {n : ℕ} {jι : Fin n → κ} (hjι : Function.Injective jι) (i : Fin n) :
    (basisCoords bL jι) (bL (jι i)) = Pi.single i 1
    theorem MultiplicativeBasisDeformations.IndSkeleton.familyCriterion_WP {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : IndSkeleton k A) (b : S.ArrowBases) (h2 : 2 = 0) {n : ℕ} {e : Fin n → A} (he : CompleteOrthogonalIdempotents e) (hprim : ∀ (i : Fin n), IsPrimitiveIdempotent (e i)) (hbasic : ∀ (i j : Fin n), (∃ (x : A) (y : A), e i * x * e j = x ∧ e j * y * e i = y ∧ x * y = e i ∧ y * x = e j) → i = j) (hconn : IsConnectedRing A) (v₀ : S.ARVertex) :
    have hF := ⋯; have dg := MeshWalk.MeshWt.res (S.arCoefficients b) (S.arMeshData b) MeshWalk.lenW; ∃ (m : ℕ) (Rw : Fin m → (x : ↑S.arTranslationQuiver.nonprojective) × Quiver.Path ↑(S.arTranslationQuiver.tau x) ↑x) (Wu : MeshWalk.MeshWt S.arTranslationQuiver (MeshWalk.WP S.arTranslationQuiver (S.arCoefficients b) v₀ (S.arMeshData b))) (hdg : dg.comp (MeshWalk.MeshWt.res (S.arCoefficients b) (S.arMeshData b) Wu) = MeshWalk.MeshWt.res (S.arCoefficients b) (S.arMeshData b) MeshWalk.lenW), MeshWalk.MeshWt.res (S.arCoefficients b) (S.arMeshData b) Wu = AddMonoidHom.id (MeshWalk.WP S.arTranslationQuiver (S.arCoefficients b) v₀ (S.arMeshData b)) ∧ Function.Injective Rw ∧ (∀ (i : Fin m), ↑(Rw i).fst ∈ S.arTranslationQuiver.periodic) ∧ (∀ (i j : Fin m), ↑(Rw j).fst ∈ S.arTranslationQuiver.component ↑(Rw i).fst → i = j) ∧ ScalarMeshCategory.CokerSpan (S.arCoefficients b) (Set.range Rw) ∧ MeshWalk.FamilyCriterionStmt (S.arMeshData b) v₀ hF Wu dg hdg Rw (S.posFiltA b he hprim hbasic)

    Proposition 7.9 (prop:family-criterion) for a basic connected representation-finite algebra A in characteristic two, with the residual characters in W(P): for the rows of Proposition 6.1 and the universal mesh weight, every family μ_i, i ∈ I₀, of normalized relative cocycles of character χ_i ∈ W(P) with nonzero classes, associative, whose binary fibres have the basis of kP as a normed multiplicative ray basis, gives A as a binary fibre with a normed multiplicative ray basis presenting P (FamilyCriterionStmt for B = A).

    theorem MultiplicativeBasisDeformations.IndSkeleton.polynomialMeshComparison_WP {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : IndSkeleton k A) (b : S.ArrowBases) (h2 : 2 = 0) (hbasic : IsBasicAlgebra A) (hconn : IsConnectedRing A) (v₀ : S.ARVertex) :
    have hF := ⋯; have dg := MeshWalk.MeshWt.res (S.arCoefficients b) (S.arMeshData b) MeshWalk.lenW; ∃ (m : ℕ) (Rw : Fin m → (x : ↑S.arTranslationQuiver.nonprojective) × Quiver.Path ↑(S.arTranslationQuiver.tau x) ↑x) (Wu : MeshWalk.MeshWt S.arTranslationQuiver (MeshWalk.WP S.arTranslationQuiver (S.arCoefficients b) v₀ (S.arMeshData b))) (hdg : dg.comp (MeshWalk.MeshWt.res (S.arCoefficients b) (S.arMeshData b) Wu) = MeshWalk.MeshWt.res (S.arCoefficients b) (S.arMeshData b) MeshWalk.lenW) (coords : MeshWalk.WP S.arTranslationQuiver (S.arCoefficients b) v₀ (S.arMeshData b) →+ Fin m → ℤ), MeshWalk.MeshWt.res (S.arCoefficients b) (S.arMeshData b) Wu = AddMonoidHom.id (MeshWalk.WP S.arTranslationQuiver (S.arCoefficients b) v₀ (S.arMeshData b)) ∧ Function.Injective Rw ∧ (∀ (i : Fin m), ↑(Rw i).fst ∈ S.arTranslationQuiver.periodic) ∧ (∀ (i j : Fin m), ↑(Rw j).fst ∈ S.arTranslationQuiver.component ↑(Rw i).fst → i = j) ∧ ScalarMeshCategory.CokerSpan (S.arCoefficients b) (Set.range Rw) ∧ (∀ (i : Fin m), 3 ≤ (Rw i).snd.length) ∧ (∀ (i : Fin m), coords (MeshWalk.rowCharG Wu Rw i) = Pi.single i 1) ∧ ∀ (μ : Fin m → (CatAlg.Alg (S.arMeshData b).F0)ᵐᵒᵖ →ₗ[k] (CatAlg.Alg (S.arMeshData b).F0)ᵐᵒᵖ →ₗ[k] (CatAlg.Alg (S.arMeshData b).F0)ᵐᵒᵖ), (∀ (i : Fin m), LenGrading.IsRel₂ (MeshWalk.VxG (S.arMeshData b) v₀ hF Wu dg hdg) (μ i)) → (∀ (i : Fin m), (MeshWalk.latA0 Wu ⋯ (S.arMeshData b)).Char₂ (MeshWalk.rowCharG Wu Rw i) (μ i)) → (∀ (i : Fin m), ¬∃ (f : (CatAlg.Alg (S.arMeshData b).F0)ᵐᵒᵖ →ₗ[k] (CatAlg.Alg (S.arMeshData b).F0)ᵐᵒᵖ), μ i = LenGrading.cobdry k f) → (∀ (t : Fin m → k) (a b' z : (CatAlg.Alg (S.arMeshData b).F0)ᵐᵒᵖ), ((MeshWalk.famMul (S.arMeshData b) μ t) (((MeshWalk.famMul (S.arMeshData b) μ t) a) b')) z = ((MeshWalk.famMul (S.arMeshData b) μ t) a) (((MeshWalk.famMul (S.arMeshData b) μ t) b') z)) → MeshWalk.PolyMeshStmtG (S.arMeshData b) Rw Wu coords (S.arInjData b) ⋯ μ

    Proposition 12.8 (prop:polynomial-mesh-comparison) for a basic connected representation-finite algebra in characteristic two, with the residual characters in W(P): for the rows of Proposition 6.1 (of length at least three) and the universal mesh weight, every family μ_i indexed by I = I₀ with the hypotheses of Proposition 7.9 has polynomial lifts with retained mesh coefficients a_i t_i, a_i ≠ 0, presenting every fibre, whose modules exhaust the indecomposables of the fibre (PolyMeshStmtG).