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 #
RS.pointMulHom,RS.pointUnitHom: the residue module as a commutative algebra over the base, with its associativityRS.pointMulHom_assoc, its two unit laws and its commutativityRS.pointMulHom_comm.RS.pointBaseMu,RS.pointBaseEps: the comparison morphisms over the algebra, withRS.pointBaseMu_naturalityand the four generator formulasRS.pointBaseMu_evenMap_eeand companions.RS.pointBaseMu_associativity,RS.pointBaseMu_left_unitality,RS.pointBaseMu_right_unitality: the three coherence laws of the comparison over the algebra — base change over the algebra is lax monoidal, and the multiplication of the residue module is what makes it so.RS.pointBaseMu_braiding: the comparison over the algebra intertwines the braidings, the residue factor contributing nothing because its multiplication is commutative.RS.modAssociator_homand its companions: the structural morphisms of the category of super modules, in the form the generator computations consume.
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.
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.
Equations
- RS.pointMulLin P = LinearMap.mk₂ ℂ (fun (a b : (RS.SuperCommAlgebra.pointMod P).even) => { down := a.down * b.down }) ⋯ ⋯ ⋯ ⋯
Instances For
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.
Equations
- One or more equations did not get rendered due to their size.
Instances For
The multiplication of the residue module, as a morphism of super modules out of its tensor square.
Equations
Instances For
The multiplication on even-even products.
The unit of the residue module: the point itself, read as a morphism from the algebra.
Equations
- RS.pointUnitHom P = { evenMap := ↑ULift.moduleEquiv.symm ∘ₗ P.chi.toLinearMap, oddMap := 0, map_actEE := ⋯, map_actEO := ⋯, map_actOE := ⋯, map_actOO := ⋯ }
Instances For
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.
Equations
- One or more equations did not get rendered due to their size.
Instances For
The unit of base change, over the algebra: the point read as a morphism from the unit, followed by the inverse left unitor.
Equations
- One or more equations did not get rendered due to their size.
Instances For
The comparison over the algebra is natural in both variables: this is naturality of the middle-four interchange.
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.
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.
The multiplication of the residue module is associative.
The point is a left unit for the multiplication of the residue module.
The point is a right unit for the multiplication of the residue module.
The multiplication of the residue module is commutative.
Base change over the algebra is lax monoidal #
Associativity of the comparison over the algebra.
Left unitality of the comparison over the algebra.
Right unitality of the comparison over the algebra.
The comparison over the algebra intertwines the braidings.
The interchange does so by RS.tensorμ_braiding, and the residue
factor by commutativity of its multiplication.