香蕉视频

TITLE: Thin right-angled Coxeter subgroups of some arithmetic lattices

ABSTRACT: Roughly speaking, a subgroup of a lattice in a semisimple Lie group is said to be thin if the subgroup is of infinite index in the lattice but is Zariski-dense in the Lie group. Free groups and surface groups have many manifestations as thin subgroups of lattices in Lie groups, by classical work of Tits in the free case, and by work of Kahn鈥揗arkovic, Hamenst盲dt, Long鈥揜eid, Kahn鈥揕abourie鈥揗ozes, and others in the surface group case. We sketch an argument that an irreducible right-angled Coxeter group on n>2 vertices embeds as a thin subgroup of an arithmetic lattice in O(p,q) for some p,q>0 satisfying p+q=n, and that we can arrange for the lattice to be cocompact