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LeanPool.RegtsSevenster.RS.Classical.Deligne.PointMonoidal.Residue

The residue algebra of a complex point #

The residue module of a ℂ-point of a super-commutative algebra S has a copy of ℂ for its even part and a vanishing odd part, and the point makes S act through its value. Multiplication of complex numbers therefore descends to a morphism k ⊗ k ⟶ k of super modules, and the point itself to a morphism from the unit module, so the residue module is a commutative monoid object. Super modules over S are symmetric monoidal, so the middle-four interchange followed by that multiplication is a comparison (M ⊗ k) ⊗ (N ⊗ k) ⟶ (M ⊗ N) ⊗ k, natural in both variables, and the monoid laws are exactly what makes it lax monoidal and braided. The comparison is carried down to super vector spaces in Comparison.lean.

Contents #

The residue module is a commutative algebra #

The odd part of the residue module has one element.

An element of the odd part of the residue module vanishes.

theorem RS.pointMod_actEE {S : SuperCommAlgebra} (P : SuperPoint S) (x : S.even) (c : (SuperCommAlgebra.pointMod P).even) :
((SuperCommAlgebra.pointMod P).actEE x) c = { down := P.chi x * c.down }

The even action on the residue module is multiplication by the value of the point.

The odd action on the even part of the residue module vanishes.

The odd action on the odd part of the residue module vanishes.

The multiplication of the residue module, on even parts: the residue module is a copy of ℂ in even degree, and this is the multiplication of ℂ.

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    @[simp]
    theorem RS.pointMulLin_apply {S : SuperCommAlgebra} (P : SuperPoint S) (a b : (SuperCommAlgebra.pointMod P).even) :
    ((pointMulLin P) a) b = { down := a.down * b.down }

    The multiplication of the residue module, evaluated.

    The data of the multiplication of the residue module as a morphism out of the tensor square: the even-even block is the multiplication of ℂ and the three remaining blocks vanish, the odd part of the residue module being zero.

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      The multiplication of the residue module, as a morphism of super modules out of its tensor square.

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        @[simp]

        The multiplication on even-even products.

        The unit of the residue module: the point itself, read as a morphism from the algebra.

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          @[simp]
          theorem RS.pointUnitHom_evenMap {S : SuperCommAlgebra} (P : SuperPoint S) (x : S.even) :
          (pointUnitHom P).evenMap x = { down := P.chi x }

          The unit of the residue module, evaluated.

          The base change of the unit module is finite dimensional in even degree: the left unitor identifies it with the residue module.

          The base change of the unit module is finite dimensional in odd degree.

          The comparison over the algebra #

          Base change is the functor M ↦ M ⊗ k for k the residue module of the point. The residue module is a commutative algebra, so the usual middle-four interchange followed by its multiplication is a comparison morphism (M ⊗ k) ⊗ (N ⊗ k) ⟶ (M ⊗ N) ⊗ k.

          The comparison morphism of base change, over the algebra: interchange the middle two factors and multiply the two copies of the residue module.

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            The unit of base change, over the algebra: the point read as a morphism from the unit, followed by the inverse left unitor.

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              The comparison over the algebra, on generators #

              The monoidal associator of the super modules is the explicit associator.

              The inverse associator of the super modules is explicit.

              theorem RS.modBraiding_hom {S : SuperCommAlgebra} (X Y : S.Mod) :
              (β_ X Y).hom = X.braidingHom Y

              The braiding of the super modules is the Koszul swap.

              Left whiskering of super modules is a tensor product of morphisms.

              Right whiskering of super modules is a tensor product of morphisms.

              The monoidal tensor product of super modules is the balanced tensor product.

              The left unitor of the super modules is explicit.

              The right unitor of the super modules is explicit.

              The monoidal unit of the super modules is the algebra.

              The comparison over the algebra on even-even generators.

              The comparison over the algebra on odd-odd generators.

              The comparison over the algebra on even-odd generators.

              The comparison over the algebra on odd-even generators.

              The residue module is a commutative monoid object #

              The three monoid laws and commutativity, in the form the lax structure of base change consumes. Every law is an identity of complex numbers in the even-even-even block, and every other block lands in the odd part of the residue module, which vanishes.

              Base change over the algebra is lax monoidal #