Existence of Equivariant Models of Spherical Varieties and Other G-varieties.

Let be a field of characteristic with algebraic closure. Let be a connected reductive -group, and let be a spherical variety over (a spherical homogeneous space or a spherical embedding). Let be a -model (-form) of. We give necessary and sufficient conditions for the existence of a -equivariant -model of. [ABSTRACT FROM AUTHOR]