On abstract representations of the groups of rational points of   algebraic groups in positive characteristic
  We analyze the structure of a large class of connected algebraic rings over an algebraically closed field of positive characteristic using Greenberg's perfectization functor. We then give applications to rigidity problems for representations of Chevalley groups, recovering, in particular, a rigidity theorem of Seitz. 
Mitya Boyarchenko, Igor A. Rapinchuk
math.GR math.AG math.NT math.RT