Julien Paupert


Title: Discrete complex reflection groups in PU(2,1)

Abstract: The group PU(n,1) of holomorphic isometries of complex hyperbolic space is one of the two occurrences (with PO(n,1)) of a simple real Lie group of rank 1 where Margulis superrigidity does not hold. The only known examples of nonarithmetic lattices in PU(2,1) were constructed by Mostow in the 1980's. We will recall the construction of these lattices, which are generated by complex reflections, and we will show how to find new examples of the same kind in a family of configuration polygons. This is joint work with John Parker (Durham).

April 28 & 29, 2007, Salt Lake City, Utah