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Mathlib.Geometry.RingedSpace.LocallyRingedSpace

The category of locally ringed spaces #

We define (bundled) locally ringed spaces (as SheafedSpace CommRing along with the fact that the stalks are local rings), and morphisms between these (morphisms in SheafedSpace with is_local_ring_hom on the stalk maps).

A LocallyRingedSpace is a topological space equipped with a sheaf of commutative rings such that all the stalks are local rings.

A morphism of locally ringed spaces is a morphism of ringed spaces such that the morphisms induced on stalks are local ring homomorphisms.

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    An alias for to_SheafedSpace, where the result type is a RingedSpace. This allows us to use dot-notation for the RingedSpace namespace.

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      The underlying topological space of a locally ringed space.

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        A morphism of locally ringed spaces is a morphism of ringed spaces such that the morphisms induced on stalks are local ring homomorphisms.

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          The identity morphism on a locally ringed space.

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            Composition of morphisms of locally ringed spaces.

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              The forgetful functor from LocallyRingedSpace to SheafedSpace CommRing.

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                Given two locally ringed spaces X and Y, an isomorphism between X and Y as sheafed spaces can be lifted to a morphism X ⟶ Y as locally ringed spaces.

                See also iso_of_SheafedSpace_iso.

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                  Given two locally ringed spaces X and Y, an isomorphism between X and Y as sheafed spaces can be lifted to an isomorphism X ⟶ Y as locally ringed spaces.

                  This is related to the property that the functor forget_to_SheafedSpace reflects isomorphisms. In fact, it is slightly stronger as we do not require f to come from a morphism between locally ringed spaces.

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                    @[simp]
                    theorem AlgebraicGeometry.LocallyRingedSpace.restrict_presheaf_map {U : TopCat} (X : AlgebraicGeometry.LocallyRingedSpace) {f : U AlgebraicGeometry.LocallyRingedSpace.toTopCat X} (h : OpenEmbedding f) :
                    ∀ {X_1 Y : (TopologicalSpace.Opens U)ᵒᵖ} (f_1 : X_1 Y), (AlgebraicGeometry.LocallyRingedSpace.restrict X h).toSheafedSpace.toPresheafedSpace.presheaf.toPrefunctor.map f_1 = X.presheaf.toPrefunctor.map ((IsOpenMap.functor (_ : IsOpenMap f)).toPrefunctor.map f_1.unop).op
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                    theorem AlgebraicGeometry.LocallyRingedSpace.restrict_presheaf_obj {U : TopCat} (X : AlgebraicGeometry.LocallyRingedSpace) {f : U AlgebraicGeometry.LocallyRingedSpace.toTopCat X✝} (h : OpenEmbedding f) (X : (TopologicalSpace.Opens U)ᵒᵖ) :
                    (AlgebraicGeometry.LocallyRingedSpace.restrict X✝ h).toSheafedSpace.toPresheafedSpace.presheaf.toPrefunctor.obj X = X✝.presheaf.toPrefunctor.obj (Opposite.op ((IsOpenMap.functor (_ : IsOpenMap f)).toPrefunctor.obj X.unop))

                    The restriction of a locally ringed space along an open embedding.

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                      The canonical map from the restriction to the subspace.

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                        instance AlgebraicGeometry.LocallyRingedSpace.component_nontrivial (X : AlgebraicGeometry.LocallyRingedSpace) (U : TopologicalSpace.Opens X.toPresheafedSpace) [hU : Nonempty U] :
                        Nontrivial (X.presheaf.toPrefunctor.obj (Opposite.op U))
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