Homogeneous variety

In algebraic geometry, a homogeneous variety is an algebraic variety on which an algebraic group acts transitively. Homogeneous varieties over an algebraically closed field are quotient varieties G/H where G is an algebraic group and H a subgroup scheme (for instance, an algebraic subgroup).

Such varieties are always smooth quasi-projective varieties.

Classical examples are flag varieties (when G is semisimple and H a parabolic subgroup), or more generally homogeneous spherical varieties. Severi-Brauer varieties are examples of homogeneous varieties over a field without any rational points.

See also

References

  1. ↑ Michel Brion, "Introduction to actions of algebraic groups" , Definition 1.17
  2. ↑ Chow, Wei-Liang (1957). "On the projective embedding of homogeneous varieties". Princeton Mathematical Series. 12: 122–128.
  3. ↑ Michel Brion, "Introduction to actions of algebraic groups" , Theorem 1.16