Magnitude conjecture

MagnitudeConjecture.Algebra.RightModuleStandardFormRecovery

Recovery from the projective vertices of the standard mesh #

Restriction from finite contravariant modules on the whole standard mesh to the full subcategory on its projective vertices is an equivalence on projective objects. The proof compares the Auslander--Bongartz--Gabriel equivalence with kernel realization and uses two injective presentations to show that every target module is such a kernel.

Consequently the restricted Yoneda functor is full, and every indecomposable finite module on the projective vertices is represented by a standard-mesh vertex.

@[instance_reducible]
def MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.standardFormRecoveryQuiver {k A : Type u} [Field k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : FiniteIndecomposableSkeleton k A) :
Quiver (Fin S.n)
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    @[instance_reducible]
    noncomputable def MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.standardFormRecoveryArrowFintype {k A : Type u} [Field k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : FiniteIndecomposableSkeleton k A) (x y : Fin S.n) :
    Fintype (x ⟶ y)
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      @[reducible, inline]
      abbrev MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.StandardFormProjectiveVertexModuleCategory {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : FiniteIndecomposableSkeleton k A) :
      Type (u + 1)

      Finite contravariant modules on the projective vertices of the standard mesh.

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        Restriction of projective-injective whole-mesh modules, with the target injectivity witness forgotten.

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          Kernel realization after restricting projective-injective whole-mesh modules to the projective vertices.

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            Every finite module on the projective vertices has a two-term kernel presentation by restricted projective-injective whole-mesh modules.

            The equivalence obtained by realizing formal arrows as kernels after restriction to the projective vertices.

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              noncomputable def MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.standardFormProjectiveModuleRestrictionFunctor {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : FiniteIndecomposableSkeleton k A) :

              Restriction from projective whole-mesh modules to finite modules on the projective vertices.

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                Forgetting the projectivity witness after the standard-form Auslander--Bongartz--Gabriel equivalence recovers its kernel realization functor.

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                  The composite of the Auslander--Bongartz--Gabriel equivalence with projective restriction agrees with restricted kernel realization.

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                    Projective restriction as an explicit equivalence.

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                      noncomputable def MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.standardFormMeshVertexFunctor {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : FiniteIndecomposableSkeleton k A) :

                      The strict standard-mesh category and its induced vertex category have the same objects and morphisms.

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                        noncomputable def MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.standardFormMeshRawFunctor {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : FiniteIndecomposableSkeleton k A) :

                        The concrete inverse from the induced vertex category back to the strict raw standard-mesh category.

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                          noncomputable def MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.standardFormVertexRestrictedYonedaFunctor {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : FiniteIndecomposableSkeleton k A) :

                          Restricted Yoneda written on the literal vertex model of the standard mesh.

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                            instance MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.standardFormRestrictedYonedaFunctor_additive {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : FiniteIndecomposableSkeleton k A) :
                            noncomputable def MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.standardFormRepresentableProjectiveFunctor {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : FiniteIndecomposableSkeleton k A) :

                            A standard-mesh vertex, sent to its finite contravariant representable and bundled as a projective whole-mesh module.

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                              Restricting the projective representable attached to a mesh vertex is the restricted Yoneda module of that vertex.

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                                instance MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.standardFormRestrictedYonedaFunctor_full {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : FiniteIndecomposableSkeleton k A) :
                                theorem MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.standardFormProjectiveRestriction_indecomposable_underlying {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : FiniteIndecomposableSkeleton k A) (P : CategoryTheory.ProjectiveObject S.StandardFormFiniteContravariantModuleCategory) (hP : CategoryTheory.Indecomposable (S.standardFormProjectiveModuleRestrictionFunctor.obj P)) :
                                CategoryTheory.Indecomposable P.obj

                                If the restriction of a projective whole-mesh module is indecomposable, then its underlying whole-mesh module is indecomposable.

                                theorem MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.standardFormRestrictedYonedaFunctor_indec_dense {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : FiniteIndecomposableSkeleton k A) (M : S.StandardFormProjectiveVertexModuleCategory) (hM : CategoryTheory.Indecomposable M) :
                                ∃ (X : S.StandardFormMeshCategory), Nonempty ((S.standardFormRestrictedYonedaFunctor ⋯).obj X ≅ M)

                                Every indecomposable finite module on the projective vertices is the restricted Yoneda module of a standard-mesh vertex.

                                @[reducible, inline]
                                abbrev MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.StandardFormAdditiveMeshCategory {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : FiniteIndecomposableSkeleton k A) :

                                The finite additive hull of the strict standard-mesh category.

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                                  noncomputable def MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.standardFormAdditiveRestrictedYonedaFunctor {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : FiniteIndecomposableSkeleton k A) :

                                  The additive extension of restricted Yoneda from mesh vertices to finite formal sums of mesh vertices.

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                                    On a singleton matrix object, additive restricted Yoneda is the original restricted Yoneda module.

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                                      instance MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.standardFormAdditiveRestrictedYonedaFunctor_essSurj {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : FiniteIndecomposableSkeleton k A) :
                                      instance MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.standardFormAdditiveRestrictedYonedaFunctor_isEquivalence {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : FiniteIndecomposableSkeleton k A) :
                                      noncomputable def MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.standardFormAdditiveRestrictedYonedaEquivalence {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : FiniteIndecomposableSkeleton k A) :

                                      The finite additive hull of the standard mesh is equivalent to finite modules on its projective vertices.

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                                        noncomputable def MagnitudeConjecture.RightModule.FiniteIndecomposableSkeleton.standardFormAdditiveMeshModuleEquivalence {k A : Type u} [Field k] [IsAlgClosed k] [Ring A] [Algebra k A] [FiniteDimensional k A] [IsNoetherianRing Aᵐᵒᵖ] (S : FiniteIndecomposableSkeleton k A) :

                                        Algebra-facing form of standard-mesh recovery: its finite additive hull is equivalent to finitely generated right modules over the standard-form category algebra.

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