Documentation

Mathlib.AlgebraicGeometry.AffineSpace

Affine space #

Main definitions #

noncomputable def AlgebraicGeometry.AffineSpace (n : Type v) (S : Scheme) :

๐”ธ(n; S) is the affine n-space over S. Note that n is an arbitrary index type (e.g. Fin m).

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    ๐”ธ(n; S) is the affine n-space over S.

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      @[implicit_reducible]
      noncomputable instance AlgebraicGeometry.AffineSpace.over (n : Type v) (S : Scheme) :
      noncomputable def AlgebraicGeometry.AffineSpace.toSpecMvPoly (n : Type v) (S : Scheme) :
      AffineSpace n S โŸถ Spec (CommRingCat.of (MvPolynomial n (ULift.{max u v, 0} โ„ค)))

      The map from the affine n-space over S to the integral model Spec โ„ค[n].

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        noncomputable def AlgebraicGeometry.AffineSpace.toSpecMvPolyIntEquiv (n : Type v) {X : Scheme} :
        (X โŸถ Spec (CommRingCat.of (MvPolynomial n (ULift.{u, 0} โ„ค)))) โ‰ƒ (n โ†’ โ†‘(X.presheaf.obj (Opposite.op โŠค)))

        Morphisms into Spec โ„ค[n] are equivalent the choice of n global sections. Use homOverEquiv instead.

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          noncomputable def AlgebraicGeometry.AffineSpace.coord {n : Type v} (S : Scheme) (i : n) :

          The standard coordinates of ๐”ธ(n; S).

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            noncomputable def AlgebraicGeometry.AffineSpace.homOfVector {n : Type v} {S X : Scheme} (f : X โŸถ S) (v : n โ†’ โ†‘(X.presheaf.obj (Opposite.op โŠค))) :

            The morphism X โŸถ ๐”ธ(n; S) given by a X โŸถ S and a choice of n-coordinate functions.

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              noncomputable def AlgebraicGeometry.AffineSpace.homOverEquiv {n : Type v} (S : Scheme) {X : Scheme} [X.Over S] :
              { f : X โŸถ AffineSpace n S // Scheme.Hom.IsOver f S } โ‰ƒ (n โ†’ โ†‘(X.presheaf.obj (Opposite.op โŠค)))

              S-morphisms into Spec ๐”ธ(n; S) are equivalent to the choice of n global sections.

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                @[simp]
                theorem AlgebraicGeometry.AffineSpace.homOverEquiv_symm_apply_coe {n : Type v} (S : Scheme) {X : Scheme} [X.Over S] (v : n โ†’ โ†‘(X.presheaf.obj (Opposite.op โŠค))) :
                โ†‘((homOverEquiv S).symm v) = homOfVector (X โ†˜ S) v

                The affine space over an affine base is isomorphic to the spectrum of the polynomial ring. Also see AffineSpace.SpecIso.

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                  The affine space over an affine base is isomorphic to the spectrum of the polynomial ring.

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                    noncomputable def AlgebraicGeometry.AffineSpace.map (n : Type v) {S T : Scheme} (f : S โŸถ T) :

                    ๐”ธ(n; S) is functorial w.r.t. S.

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                      The map between affine spaces over affine bases is isomorphic to the natural map between polynomial rings.

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                        noncomputable def AlgebraicGeometry.AffineSpace.reindex {n m : Type v} (i : m โ†’ n) (S : Scheme) :

                        ๐”ธ(n; S) is functorial w.r.t. n.

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                          @[simp]
                          theorem AlgebraicGeometry.AffineSpace.reindex_comp {nโ‚ nโ‚‚ nโ‚ƒ : Type v} (i : nโ‚ โ†’ nโ‚‚) (j : nโ‚‚ โ†’ nโ‚ƒ) (S : Scheme) :
                          theorem AlgebraicGeometry.AffineSpace.reindex_comp_assoc {nโ‚ nโ‚‚ nโ‚ƒ : Type v} (i : nโ‚ โ†’ nโ‚‚) (j : nโ‚‚ โ†’ nโ‚ƒ) (S : Scheme) {Z : Scheme} (h : AffineSpace nโ‚ S โŸถ Z) :
                          @[simp]
                          theorem AlgebraicGeometry.AffineSpace.map_reindex {nโ‚ nโ‚‚ : Type v} (i : nโ‚ โ†’ nโ‚‚) {S T : Scheme} (f : S โŸถ T) :
                          @[simp]
                          theorem AlgebraicGeometry.AffineSpace.map_reindex_assoc {nโ‚ nโ‚‚ : Type v} (i : nโ‚ โ†’ nโ‚‚) {S T : Scheme} (f : S โŸถ T) {Z : Scheme} (h : AffineSpace nโ‚ T โŸถ Z) :
                          @[simp]
                          theorem AlgebraicGeometry.AffineSpace.functor_obj_map (n : Type vแต’แต–) {Xโœ Yโœ : Scheme} (f : Xโœ โŸถ Yโœ) :
                          theorem AlgebraicGeometry.AffineSpace.not_isIntegralHom {n : Type v} (S : Scheme) [Nonempty โ†ฅS] [Nonempty n] :