English

Orbits of actions of group superschemes

Representation Theory 2022-02-24 v1 Algebraic Geometry

Abstract

Working over an algebraically closed field k\Bbbk, we prove that all orbits of a left action of an algebraic group superscheme GG on a superscheme XX of finite type are locally closed. Moreover, such an orbit GxGx, where xx is a k\Bbbk-point of XX, is closed if and only if GevxG_{ev}x is closed in XevX_{ev}, or equivalently, if and only if GresxG_{res}x is closed in XresX_{res}. Here GevG_{ev} is the largest purely even group super-subscheme of GG and GresG_{res} is GevG_{ev} regarded as a group scheme. Similarly, XevX_{ev} is the largest purely even super-subscheme of XX and XresX_{res} is XevX_{ev} regarded as a scheme. We also prove that sdim(Gx)=sdim(G)sdim(Gx)\mathrm{sdim}(Gx)=\mathrm{sdim}(G)-\mathrm{sdim}(G_x), where GxG_x is the stabilizer of xx.

Keywords

Cite

@article{arxiv.2202.09384,
  title  = {Orbits of actions of group superschemes},
  author = {V. A. Bovdi and A. N. Zubkov},
  journal= {arXiv preprint arXiv:2202.09384},
  year   = {2022}
}