Serre's theorem on affineness

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In the mathematical discipline of algebraic geometry, Serre's theorem on affineness (also called Serre's cohomological characterization of affineness or Serre's criterion on affineness) is a theorem due to Jean-Pierre Serre which gives sufficient conditions for a scheme to be affine. [1] The theorem was first published by Serre in 1957. [2]

Contents

Statement

Let X be a scheme with structure sheaf OX. If:

(1) X is quasi-compact, and
(2) for every quasi-coherent ideal sheaf I of OX-modules, H1(X, I) = 0, [lower-alpha 1]

then X is affine. [3]

Notes

  1. Some texts, such as Ueno (2001, pp. 128–133), require that Hi(X,I) = 0 for all i  1 as a condition for the theorem. In fact, this is equivalent to condition (2) above.

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References

  1. Stacks 01XF.
  2. Serre (1957).
  3. Stacks 01XF.
  4. Stacks 01XE, Lemma 29.3.2.

Bibliography