English

Poisson deformations and birational geometry

Algebraic Geometry 2014-04-08 v6

Abstract

Let \pi: Y -> X be a crepant projective resolution of an affine symplectic variety X with a good C^*-action. We interpret the second cohomology H^2(Y, C) in two ways. First, H^2(Y, C) is the Picard group of Y tensorised with C. By the ample cones of different crepant resolutions of X, there is a natural chamber structure in H^2(Y, C). The second interpretation of H^2(Y, C) is the base space of the universal Poisson deformation Y\mathcal Y of Y. Let D \subset H^2(Y, C) be the locus where the corresponding Poisson varieties are not affine. Then D is the union of finite number of hyperplanes, which gives a chamber structure in H^2(Y, C). These two chamber structures coincide.

Keywords

Cite

@article{arxiv.1305.1698,
  title  = {Poisson deformations and birational geometry},
  author = {Yoshinori Namikawa},
  journal= {arXiv preprint arXiv:1305.1698},
  year   = {2014}
}

Comments

15 pages, the title of the article is slightly changed

R2 v1 2026-06-22T00:13:12.750Z