4 papers · 1 filter
Groups that do not act by automorphisms of codimension-one foliations
Renato Feres, Dave Witte
Let G be a finitely generated group having the property that any action of any finite-index subgroup of G by homeomorphisms of the circle must have a finite orbit. (By a theorem of…
Homogeneous Lorentz manifolds with simple isometry group
Dave Witte
Let H be a closed, noncompact subgroup of a simple Lie group G, such that G/H admits an invariant Lorentz metric. We show that if G = SO(2,n), with n > 2, then the identity compone…
On automorphisms of arithmetic subgroups of unipotent groups in positive characteristic
Lucy Lifschitz, Dave Witte
Let F be a local field of positive characteristic, and let G be either a Heisenberg group over F, or a certain (nonabelian) two-dimensional unipotent group over F. If H is an arith…
Cartan-decomposition subgroups of SU(2,n)
Alessandra Iozzi, Dave Witte
We give explicit, practical conditions that determine whether or not a closed, connected subgroup H of G = SU(2,n) has the property that there exists a compact subset C of G with C…