A joining classification and a special case of Raghunathan's conjecture in positive characteristic (with an appendix by Kevin Wortman)

Manfred Einsiedler, Amir Mohammadi

Published 2010-10-26Version 1

We prove the classification of joinings for maximal horospherical subgroups acting on homogeneous spaces without any restriction on the characteristic. Using the linearization technique we deduce a special case of Raghunathan's orbit closure conjecture. In the appendix quasi-isometries of higher rank lattices in semisimple algebraic groups over fields of positive characteristic are characterized.