Morphisms of pure Hodge structures #
A morphism between integral pure Hodge structures of the same weight is an integral linear map whose complexification preserves the Hodge filtration. The complex action is derived canonically from the integral map through the universal property of the source base change; in particular, it commutes with the lattice-induced conjugations.
Those two properties — commuting with the conjugations and preserving the filtration — are also
what a morphism of pure Hodge structures amounts to on the conjugation-parametric object
TauCeti.Hodge.HodgeStructureOn, where no lattice is in sight. They are recorded there as the
unbundled predicate TauCeti.Hodge.HodgeStructureOn.IsMorphism, from which the integral morphism
calculus below is derived: preservation of the filtration and compatibility with conjugation imply
preservation of the conjugate filtration and hence of every Hodge component H^{p,n-p}.
The rest of the file develops the elementary morphism calculus. Morphisms are closed under identities and composition, and form an additive commutative group.
Main declarations #
TauCeti.Hodge.HodgeStructureOn.IsMorphism: a complex-linear map commuting with the conjugations and preserving the Hodge filtration — a morphism of pure Hodge structures in unbundled, lattice-free form.TauCeti.Hodge.HodgeStructure.Hom: morphisms of integral pure Hodge structures of a fixed weight, withTauCeti.Hodge.HodgeStructure.Hom.isMorphismexhibiting one as such a map.TauCeti.Hodge.HodgeStructure.Hom.idandHom.comp: identity and composition.TauCeti.Hodge.HodgeStructure.Hom.map_conjF_le: morphisms preserve the conjugate filtration.TauCeti.Hodge.HodgeStructure.Hom.map_piece_le: morphisms preserve every Hodge component.
This supplies the morphism companion in Layer L0 of
TauCetiRoadmap/HodgeStructures/README.md. It follows the opposed-filtration convention of
Deligne, Théorie de Hodge II, §1.2.1, and the usual morphism convention in Voisin,
Hodge Theory and Complex Algebraic Geometry I, §7.
A morphism of pure Hodge structures of weight n, in unbundled form: a complex-linear map
commuting with the two conjugations and preserving every step of the Hodge filtration.
The bundled integral morphisms TauCeti.Hodge.HodgeStructure.Hom are of this form, by
TauCeti.Hodge.HodgeStructure.Hom.isMorphism.
The map commutes with the two conjugations.
The map preserves every step of the Hodge filtration.
Instances For
The identity map is a morphism of pure Hodge structures.
The composite of two morphisms of pure Hodge structures is a morphism.
The zero map is a morphism of pure Hodge structures.
The sum of two morphisms of pure Hodge structures is a morphism.
The negation of a morphism of pure Hodge structures is a morphism.
The difference of two morphisms of pure Hodge structures is a morphism.
A morphism of pure Hodge structures preserves the conjugate Hodge filtration.
A morphism of pure Hodge structures preserves every Hodge component H^{p,n-p}.
A morphism between integral pure Hodge structures of the same weight.
Its primary datum is an integral linear map. Its complexification is derived from the source
IsBaseChange witness together with the target integral inclusion, and is required to preserve
every step of the Hodge filtration.
The integral linear map underlying a Hodge morphism.
- map_mem_F (p : ℤ) (x : W₁) : x ∈ source.F p → (integralMapToComplex h₁ ι₂ self.toIntLinearMap) x ∈ target.F p
The complexification of the underlying map preserves every Hodge filtration step.
Instances For
The complex-linear map induced by an integral Hodge morphism.
Instances For
The complex action of a Hodge morphism is the complexification of its integral map. This is
the bridge to the TauCeti.Hodge.integralMapToComplex API.
A Hodge morphism acts on complex vectors through the complexification of its integral map.
A Hodge morphism acts on integral vectors by its underlying integral map.
Two Hodge morphisms are equal when their integral maps agree on every vector.
The complex action of a Hodge morphism commutes with lattice-induced conjugation.
Preservation of a filtration step in submodule-map form.
A bundled integral Hodge morphism is a morphism of the underlying pure Hodge structures.
A Hodge morphism preserves the conjugate Hodge filtration.
Elementwise form of preservation of the conjugate Hodge filtration.
A Hodge morphism preserves every Hodge component H^{p,n-p}.
Elementwise form of preservation of Hodge components.
The identity morphism of an integral pure Hodge structure.
Instances For
The identity Hodge morphism acts as the identity on integral vectors.
The identity Hodge morphism acts as the identity on complex vectors.
Composition of morphisms of integral pure Hodge structures.
Instances For
The integral map underlying a composite is the composite of the integral maps.
Composition of Hodge morphisms is pointwise composition on complex vectors.
Left identity law for Hodge morphisms.
Right identity law for Hodge morphisms.
Associativity of composition of Hodge morphisms.
The zero morphism between two integral pure Hodge structures.
Addition of Hodge morphisms, defined on their integral maps.
Negation of a Hodge morphism, defined on its integral map.
Subtraction of Hodge morphisms, defined on their integral maps.
Natural-number multiples of a Hodge morphism, defined on its integral map.
Integer multiples of a Hodge morphism, defined on its integral map.
Integral Hodge morphisms form an additive commutative group, transported along the injection sending a morphism to its underlying integral linear map.
The zero Hodge morphism has the zero integral linear map underneath.
Addition of Hodge morphisms is addition of their underlying integral linear maps.
Negation of a Hodge morphism is negation of its underlying integral linear map.
Subtraction of Hodge morphisms is subtraction of their underlying integral linear maps.
Natural-number multiples of Hodge morphisms pass to their underlying integral linear maps.
Integer multiples of Hodge morphisms pass to their underlying integral linear maps.
The zero Hodge morphism acts as zero on complex vectors.
Addition of Hodge morphisms is pointwise addition on complex vectors.
Negation of Hodge morphisms is pointwise negation on complex vectors.
Subtraction of Hodge morphisms is pointwise subtraction on complex vectors.
Natural-number multiples of Hodge morphisms are evaluated pointwise on complex vectors.
Integer multiples of Hodge morphisms are evaluated pointwise on complex vectors.
Composition is additive in the morphism applied second.
Composition is additive in the morphism applied first.
Composing with a zero morphism on the left gives zero.
Composing with a zero morphism on the right gives zero.