The functor from analytic manifolds to analytic spaces is fully faithful #
A K-morphism F : Sp(M) ⟶ Sp(N) between the analytic spaces of two manifolds is induced by a
unique analytic map, namely its underlying map toSpaceFun ψ F : M → N (toSpace_fullyFaithful).
This is not stated in the sources; it is what makes the local coordinations of
[Hir64, Ch. 0, §1, p. 120], which are K-morphisms into (Kⁿ, 𝒜_{Kⁿ}), the same thing as charts.
The proof:
- Evaluation is preserved by the stalk maps (
eval_stalkMap): for a germσatF ywith valuec,σ - cis a non-unit; the stalk map is a localK-homomorphism sending constants to constants, soF^*σ - cis a non-unit, i.e.F^*σhas valuec. Hence a pulled-back section has the composed values,(F^*s)(y) = s(F y)(sheafHom_apply): the sheaf map of aK-morphism of sheaves of functions is precomposition with the underlying map. - The underlying map is analytic (
contMDiff_baseFun): in a chartχatF xwith coordinatesψ', the coordinate functionsψ'_i ∘ χ(chartSection) pull back to analytic functions onF⁻¹(χ.source)whose values areψ'_i (χ (F y)), soχ ∘ Fis analytic nearx. - Two local
K-homomorphisms out of a stalk𝒪_{N,b}agreeing on the coordinate germs of a chart agree (ringHom_ext_of_coord'): Hadamard's lemma (exists_eq_sum_coord_mul') gives the𝔪-adic approximation of every germ by polynomials in the coordinates, and Krull's intersection theorem in the Noetherian target finishes. - A
K-morphism is determined by its underlying map (hom_ext_baseFun): the stalk maps atyof two morphisms with the same base map are localK-homomorphisms𝒪_{N, F y} → 𝒪_{M, y}into a Noetherian local ring which agree on the coordinate germs, because the pulled-back coordinate sections have the same values; hence they agree, and a morphism of sheaves is determined by its stalk maps.
Then toSpaceHom ψ : AnalyticMap M N → (Sp(M) ⟶ Sp(N)) is injective (toSpaceHom_injective) and
surjective (exists_toSpaceHom_eq, the analytic map being
⟨toSpaceFun F, contMDiff_toSpaceFun F⟩). The extensionality on points is used to show that a
comparison morphism is an isomorphism chart by chart (Hironaka.AnalyticSpace.Manifold.StratumIso)
and for morphisms into a non-singular space (Hironaka.AnalyticSpace.HomExtNonSingular); the stalk
lemma ringHom_ext_of_coord' is used for the uniqueness of lifts through a blow-up chart
(Hironaka.AnalyticSpace.MonoidalUnique) and in the gluing of local resolutions
(Hironaka.Resolution.Analytic.Kol07Thm45.PieceLemma39Model,
Hironaka.Resolution.Analytic.Kol07Thm45.PieceLemma39Shear).
The underlying map M → N of a K-morphism Sp(M) ⟶ Sp(N), with the manifolds' types.
Equations
Instances For
The stalk map of a K-morphism preserves the value of a germ: σ - σ(F y) is a non-unit,
so is its image, which is F^*σ - σ(F y).
A pulled-back section has the composed values, (F^*s)(y) = s(F y).
The underlying map of a K-morphism between the spaces of two manifolds is analytic: in a
chart χ at F x, the coordinate functions of χ pull back to analytic functions whose values are
the coordinates of χ ∘ F.
Two local ring homomorphisms from 𝒪_{M,a} into a Noetherian local ring that agree on the
constants and on the coordinate germs of a chart at a agree: Hadamard's lemma gives the 𝔪-adic
approximation by polynomials in the coordinates, and Krull's intersection theorem finishes (the form
of ringHom_ext_of_coord for the stalk of a manifold).
A K-morphism between the spaces of two manifolds is determined by its underlying map: its
stalk maps are local K-homomorphisms into Noetherian local rings agreeing on the coordinate germs
(the pulled-back coordinate sections have the same values), and a morphism of sheaves is determined
by its stalk maps. ψ' supplies the coordinates on the target's model space E': the coordinate
germs ψ'_i ∘ χ of a chart χ at F x generate the maximal ideal of 𝒪_{N, F x}, and the two
stalk maps agree on them because the pulled-back coordinate sections have the same values along the
common underlying map; ψ gives the Noetherianity of the stalks of the source through its charts.
The underlying map M → N of a morphism Sp(M) ⟶ Sp(N), with the manifolds' types (the base
map of the morphism of locally ringed spaces).
Equations
- AnalyticSpace.toSpaceFun ψ F x = (CategoryTheory.ConcreteCategory.hom (↑F).base) x
Instances For
The underlying map of a morphism Sp(M) ⟶ Sp(N) is analytic.
A morphism Sp(M) ⟶ Sp(N) is determined by its underlying map.
Sp is faithful.
Sp is full: every morphism Sp(M) ⟶ Sp(N) is Sp(f) for the analytic map f underlying it.
Sp is fully faithful: analytic maps M → N correspond bijectively to morphisms
Sp(M) ⟶ Sp(N).