Multiplicative bases

MultiplicativeBasisDeformations.Foundations.WeightTwist

Scalar automorphisms act trivially on module classes #

Lemma 4.13, first step (scalar-normalization.tex): "A weight scales morphism lines and thus defines an automorphism of L. These automorphisms act on the indecomposable module classes with any fixed finite support […]. Their permutation image is finite, abelian and divisible, hence trivial. Every scalar automorphism consequently fixes each V_X̃ up to isomorphism."

For a finite set of objects s of the graded covering category, a weight d defines the automorphism σ_d of the covering algebra cov D s scaling the (p, q)-entry by d(s p, s q) (scaleEquiv). By divisibility of weights (Lemma 4.11(2)) σ_d = σ_e^N for the N of twist_pow_iso, so σ_d fixes every finite-dimensional indecomposable class (weight_twist_iso).

def MultiplicativeBasisDeformations.CatAlg.ent {k : Type u} [Field k] {𝒞 : Type v} [CategoryTheory.Category.{u, v} 𝒞] [CategoryTheory.Preadditive 𝒞] [CategoryTheory.Linear k 𝒞] {ι : Type} [Fintype ι] [DecidableEq ι] {F : ι → 𝒞} {G : Type} [Group G] [DecidableEq G] {D : HomGrading F G} {κ : Type} [Fintype κ] [DecidableEq κ] (s : κ → CovObj D) (a : ↥(cov D s)) (p q : κ) :
s p ⟶ s q

An entry of a covering algebra element as a morphism of the cover.

Instances For
    theorem MultiplicativeBasisDeformations.CatAlg.ent_ext {k : Type u} [Field k] {𝒞 : Type v} [CategoryTheory.Category.{u, v} 𝒞] [CategoryTheory.Preadditive 𝒞] [CategoryTheory.Linear k 𝒞] {ι : Type} [Fintype ι] [DecidableEq ι] {F : ι → 𝒞} {G : Type} [Group G] [DecidableEq G] {D : HomGrading F G} {κ : Type} [Fintype κ] [DecidableEq κ] {s : κ → CovObj D} {a b : ↥(cov D s)} (h : ∀ (p q : κ), ent s a p q = ent s b p q) :
    a = b
    def MultiplicativeBasisDeformations.CatAlg.scale {k : Type u} [Field k] {𝒞 : Type v} [CategoryTheory.Category.{u, v} 𝒞] [CategoryTheory.Preadditive 𝒞] [CategoryTheory.Linear k 𝒞] {ι : Type} [Fintype ι] [DecidableEq ι] {F : ι → 𝒞} {G : Type} [Group G] [DecidableEq G] {D : HomGrading F G} {κ : Type} [Fintype κ] [DecidableEq κ] (s : κ → CovObj D) (d : CovObj D → CovObj D → k) (a : ↥(cov D s)) :
    ↥(cov D s)

    Scaling the entries by a function on pairs of objects.

    Instances For
      theorem MultiplicativeBasisDeformations.CatAlg.ent_scale {k : Type u} [Field k] {𝒞 : Type v} [CategoryTheory.Category.{u, v} 𝒞] [CategoryTheory.Preadditive 𝒞] [CategoryTheory.Linear k 𝒞] {ι : Type} [Fintype ι] [DecidableEq ι] {F : ι → 𝒞} {G : Type} [Group G] [DecidableEq G] {D : HomGrading F G} {κ : Type} [Fintype κ] [DecidableEq κ] {s : κ → CovObj D} (d : CovObj D → CovObj D → k) (a : ↥(cov D s)) (p q : κ) :
      ent s (scale s d a) p q = d (s p) (s q) • ent s a p q
      theorem MultiplicativeBasisDeformations.CatAlg.ent_mul {k : Type u} [Field k] {𝒞 : Type v} [CategoryTheory.Category.{u, v} 𝒞] [CategoryTheory.Preadditive 𝒞] [CategoryTheory.Linear k 𝒞] {ι : Type} [Fintype ι] [DecidableEq ι] {F : ι → 𝒞} {G : Type} [Group G] [DecidableEq G] {D : HomGrading F G} {κ : Type} [Fintype κ] [DecidableEq κ] {s : κ → CovObj D} (a b : ↥(cov D s)) (p r : κ) :
      ent s (a * b) p r = ∑ q : κ, CategoryTheory.CategoryStruct.comp (ent s b p q) (ent s a q r)
      theorem MultiplicativeBasisDeformations.CatAlg.ent_one {k : Type u} [Field k] {𝒞 : Type v} [CategoryTheory.Category.{u, v} 𝒞] [CategoryTheory.Preadditive 𝒞] [CategoryTheory.Linear k 𝒞] {ι : Type} [Fintype ι] [DecidableEq ι] {F : ι → 𝒞} {G : Type} [Group G] [DecidableEq G] {D : HomGrading F G} {κ : Type} [Fintype κ] [DecidableEq κ] {s : κ → CovObj D} (p q : κ) :
      ↑(ent s 1 p q) = idTo p q
      theorem MultiplicativeBasisDeformations.CatAlg.scale_mul {k : Type u} [Field k] {𝒞 : Type v} [CategoryTheory.Category.{u, v} 𝒞] [CategoryTheory.Preadditive 𝒞] [CategoryTheory.Linear k 𝒞] {ι : Type} [Fintype ι] [DecidableEq ι] {F : ι → 𝒞} {G : Type} [Group G] [DecidableEq G] {D : HomGrading F G} {κ : Type} [Fintype κ] [DecidableEq κ] {s : κ → CovObj D} {d : CovObj D → CovObj D → k} (hd : Thin.IsWeight (Set.range s) d) (a b : ↥(cov D s)) :
      scale s d (a * b) = scale s d a * scale s d b
      theorem MultiplicativeBasisDeformations.CatAlg.scale_one {k : Type u} [Field k] {𝒞 : Type v} [CategoryTheory.Category.{u, v} 𝒞] [CategoryTheory.Preadditive 𝒞] [CategoryTheory.Linear k 𝒞] {ι : Type} [Fintype ι] [DecidableEq ι] {F : ι → 𝒞} {G : Type} [Group G] [DecidableEq G] {D : HomGrading F G} {κ : Type} [Fintype κ] [DecidableEq κ] {s : κ → CovObj D} {d : CovObj D → CovObj D → k} (hd : Thin.IsWeight (Set.range s) d) :
      scale s d 1 = 1
      theorem MultiplicativeBasisDeformations.CatAlg.scale_inv_scale {k : Type u} [Field k] {𝒞 : Type v} [CategoryTheory.Category.{u, v} 𝒞] [CategoryTheory.Preadditive 𝒞] [CategoryTheory.Linear k 𝒞] {ι : Type} [Fintype ι] [DecidableEq ι] {F : ι → 𝒞} {G : Type} [Group G] [DecidableEq G] {D : HomGrading F G} {κ : Type} [Fintype κ] [DecidableEq κ] {s : κ → CovObj D} {d : CovObj D → CovObj D → k} (hd : Thin.IsWeight (Set.range s) d) (a : ↥(cov D s)) :
      scale s (fun (o o' : CovObj D) => (d o o')⁻¹) (scale s d a) = a
      theorem MultiplicativeBasisDeformations.CatAlg.scale_scale_inv {k : Type u} [Field k] {𝒞 : Type v} [CategoryTheory.Category.{u, v} 𝒞] [CategoryTheory.Preadditive 𝒞] [CategoryTheory.Linear k 𝒞] {ι : Type} [Fintype ι] [DecidableEq ι] {F : ι → 𝒞} {G : Type} [Group G] [DecidableEq G] {D : HomGrading F G} {κ : Type} [Fintype κ] [DecidableEq κ] {s : κ → CovObj D} {d : CovObj D → CovObj D → k} (hd : Thin.IsWeight (Set.range s) d) (a : ↥(cov D s)) :
      scale s d (scale s (fun (o o' : CovObj D) => (d o o')⁻¹) a) = a
      theorem MultiplicativeBasisDeformations.CatAlg.scale_add {k : Type u} [Field k] {𝒞 : Type v} [CategoryTheory.Category.{u, v} 𝒞] [CategoryTheory.Preadditive 𝒞] [CategoryTheory.Linear k 𝒞] {ι : Type} [Fintype ι] [DecidableEq ι] {F : ι → 𝒞} {G : Type} [Group G] [DecidableEq G] {D : HomGrading F G} {κ : Type} [Fintype κ] [DecidableEq κ] {s : κ → CovObj D} {d : CovObj D → CovObj D → k} (a b : ↥(cov D s)) :
      scale s d (a + b) = scale s d a + scale s d b
      theorem MultiplicativeBasisDeformations.CatAlg.scale_smul {k : Type u} [Field k] {𝒞 : Type v} [CategoryTheory.Category.{u, v} 𝒞] [CategoryTheory.Preadditive 𝒞] [CategoryTheory.Linear k 𝒞] {ι : Type} [Fintype ι] [DecidableEq ι] {F : ι → 𝒞} {G : Type} [Group G] [DecidableEq G] {D : HomGrading F G} {κ : Type} [Fintype κ] [DecidableEq κ] {s : κ → CovObj D} {d : CovObj D → CovObj D → k} (c : k) (a : ↥(cov D s)) :
      scale s d (c • a) = c • scale s d a
      def MultiplicativeBasisDeformations.CatAlg.scaleEquiv {k : Type u} [Field k] {𝒞 : Type v} [CategoryTheory.Category.{u, v} 𝒞] [CategoryTheory.Preadditive 𝒞] [CategoryTheory.Linear k 𝒞] {ι : Type} [Fintype ι] [DecidableEq ι] {F : ι → 𝒞} {G : Type} [Group G] [DecidableEq G] {D : HomGrading F G} {κ : Type} [Fintype κ] [DecidableEq κ] {s : κ → CovObj D} {d : CovObj D → CovObj D → k} (hd : Thin.IsWeight (Set.range s) d) :
      ↥(cov D s) ≃ₐ[k] ↥(cov D s)

      The scalar automorphism σ_d of the covering algebra.

      Instances For
        theorem MultiplicativeBasisDeformations.CatAlg.scaleEquiv_apply {k : Type u} [Field k] {𝒞 : Type v} [CategoryTheory.Category.{u, v} 𝒞] [CategoryTheory.Preadditive 𝒞] [CategoryTheory.Linear k 𝒞] {ι : Type} [Fintype ι] [DecidableEq ι] {F : ι → 𝒞} {G : Type} [Group G] [DecidableEq G] {D : HomGrading F G} {κ : Type} [Fintype κ] [DecidableEq κ] {s : κ → CovObj D} {d : CovObj D → CovObj D → k} (hd : Thin.IsWeight (Set.range s) d) (a : ↥(cov D s)) :
        (scaleEquiv hd) a = scale s d a
        theorem MultiplicativeBasisDeformations.CatAlg.scaleEquiv_pow {k : Type u} [Field k] {𝒞 : Type v} [CategoryTheory.Category.{u, v} 𝒞] [CategoryTheory.Preadditive 𝒞] [CategoryTheory.Linear k 𝒞] {ι : Type} [Fintype ι] [DecidableEq ι] {F : ι → 𝒞} {G : Type} [Group G] [DecidableEq G] {D : HomGrading F G} {κ : Type} [Fintype κ] [DecidableEq κ] {s : κ → CovObj D} {d : CovObj D → CovObj D → k} (hd : Thin.IsWeight (Set.range s) d) (N : ℕ) (a : ↥(cov D s)) :
        (scaleEquiv hd ^ N) a = scale s (fun (o o' : CovObj D) => d o o' ^ N) a
        theorem MultiplicativeBasisDeformations.CatAlg.weight_twist_iso {k : Type u} [Field k] {𝒞 : Type v} [CategoryTheory.Category.{u, v} 𝒞] [CategoryTheory.Preadditive 𝒞] [CategoryTheory.Linear k 𝒞] {ι : Type} [Fintype ι] [DecidableEq ι] {F : ι → 𝒞} {G : Type} [Group G] [DecidableEq G] {D : HomGrading F G} {κ : Type} [Fintype κ] [DecidableEq κ] {s : κ → CovObj D} {d : CovObj D → CovObj D → k} (hd : Thin.IsWeight (Set.range s) d) [Infinite k] [IsAlgClosed k] (H : HeightData D) [∀ (x y : ι), FiniteDimensional k (F x ⟶ F y)] (hF : IsRepresentationFinite k (Alg F)ᵐᵒᵖ) (M : RightModuleCat ↥(cov D s)) (hM : IsFiniteIndecomposable k (↥(cov D s)) M) :
        Nonempty (twist (scaleEquiv hd) M ≅ M)

        Weights fix every indecomposable class (Lemma 4.13, first step).