Leírás
Előadó: Arie Levit
Cím: Counting commensurability classes of hyperbolic manifolds
Absztrakt: An interesting direction in the study of hyperbolic manifolds is counting questions. By a classical result of Wang, in dimension > 3 there are finitely many isometry classes of hyperbolic manifolds up to any finite volume V. More recently, Burger, Gelander, Lubotzky and Mozes showed that this number grows like V^V. In this talk we focus on the number of commensurability classes of hyperbolic manifolds. Two manifolds are commensurable if they admit a common finite sheeted cover. We show that in dimension > 3 this number grows like V^V as well. Since the number of arithmetic commensurability classes grows ~ polynomially, our result implies that non-arithmetic manifolds account for “most" commensurability classes. I will explain the ideas involved in the proof, which include a mixture of arithmetic, hyperbolic geometry and some combinatorics. This is a joint work with Tsachik Gelander.