The range of a tilde map on an affine basic open #
On D(r), the range of the map of tilde sheaves induced by a module map is the
localization of its range. The statement uses the canonical
Localization.Away r-action transported to the underlying R-module of
sections by IsLocalizedModule.module. It does not identify that action
definitionally with the structure-sheaf action, nor compare categorical
coherent subobjects or glue them across opens.
theorem
AlgebraicGeometry.tilde.localized'_range_eq_range_map_basicOpen
(R : CommRingCat)
(K M : ModuleCat ↑R)
(g : K ⟶ M)
(r : ↑R)
:
let S := Submonoid.powers r;
let U := PrimeSpectrum.basicOpen r;
let fK := ModuleCat.Hom.hom (toOpen K U);
let fM := ModuleCat.Hom.hom (toOpen M U);
have h := ModuleCat.Hom.hom ((modulesSpecToSheaf.map (tilde.map g)).hom.app (Opposite.op U));
Submodule.localized' (Localization.Away r) S fM (ModuleCat.Hom.hom g).range = (LinearMap.extendScalarsOfIsLocalization S (Localization.Away r) h).range
The range of tilde.map g on D(r) is the localization away from r of
g's range. The result applies to an inclusion N.subtype as well as an
arbitrary module map. Both localized-module structures and scalar towers are
proof-local; no global instance for the section modules is introduced.