nLab affine variety



Affine kk-variety is a locus of zeros of a set of polynomials in the affine nn-dimensional space A k n\mathbf{A}^n_k. Usually kk is taken to be a field.


Given a field kk, an affine kk-variety is a maximal spectrum (= set of maximal ideals) of a finitely generated noetherian (commutative unital) kk-commutative algebra without nilpotents, equipped with the Zariski topology; the algebra can be recovered as the coordinate ring of the variety; this correspondence is an equivalence of categories, if the morphisms are properly defined.

Affine varieties can be embedded as closed subvarieties into an affine space (in the sense of algebraic geometry). As topological spaces affine varieties are noetherian.



For XX an affine variety then its abelian sheaf cohomology with coefficients in the structure sheaf satisfies

H 1(X,𝒪 X)=0. H^{\bullet \geq 1}(X,\mathcal{O}_X) = 0 \,.

The converse requires in addition some finiteness condition. (Ballico 08).


  • E. Ballico, A characterization of affine varieties 2008

Last revised on January 2, 2015 at 13:21:45. See the history of this page for a list of all contributions to it.