Now showing items 1-4 of 4

• #### Cocharacter-closure and spherical buildings ﻿

[OWP-2015-12] (Mathematisches Forschungsinstitut Oberwolfach, 2015-07-29)
Let $k$ be a field, let $G$ be a reductive $k$-group and $V$ an affine $k$-variety on which $G$ acts. In this note we continue our study of the notion of cocharacter-closed $G(k)$-orbits in $V$. In earlier work we used a ...
• #### Cocharacter-Closure and the Rational Hilbert-Mumford Theorem ﻿

[OWP-2014-16] (Mathematisches Forschungsinstitut Oberwolfach, 2014-12-20)
For a field $k$, let $G$ be a reductive $k$-group and $V$ an affine $k$-variety on which $G$ acts. Using the notion of cocharacter-closed $G(k)$-orbits in $V$ , we prove a rational version of the celebrated Hilbert-Mumford ...
• #### G-complete reducibility in non-connected groups ﻿

[OWP-2013-09] (Mathematisches Forschungsinstitut Oberwolfach, 2013-04-10)
In this paper we present an algorithm for determining whether a subgroup $H$ of a non-connected reductive group $G$ is $G$-completely reducible. The algorithm consists of a series of reductions; at each step, we perform ...
• #### On Unipotent Radicals of Pseudo-Reductive Groups ﻿

[OWP-2017-12] (Mathematisches Forschungsinstitut Oberwolfach, 2017-04-27)
We establish some results on the structure of the geometric unipotent radicals of pseudo-reductive k-groups. In particular, let $k'$ be a purely inseparable field extension of k of degree $p^e$ and let $G$ denote the ...