Recent publications

• (With N. A'Campo) Réseaux arithmétiques et commensurateur d'après G. A. Margulis, Invent. Math. 116 (1994), 1-25.
  
  
• (With D. Canary) A lower bound on the base eigenvalue for geometrically finite hyperbolic n-manifolds, J. reine angew. Math. 454 (1994), 37-57.
  
  
• Rigidity properties of group actions on CAT(0)-spaces, Proc. ICM Zürich, Switzerland 1994, 761-769 ; Birkhäuser 1995.
  
  
• (With S. Mozes) CAT(-1)-spaces, divergence groups and their commensurators, J. of the Amer. Math. Soc. 9, no 1 (1996), 57-93.
  
  
• (With P. de la Harpe) Constructing irreducible representations of discrete groups, Proc. Indian Acad. Sci. 107, no 3 (1997), 223-235.
  
  
• (With S. Mozes) Finitely presented simple groups and products of trees, C. R. Acad. Sci. Paris 324 (1997), 747-752.
  
  
• (With A. Valette) Idempotents in complex group rings : theorems of Zalesskii and Bass revisited, J. of Lie Theory 8 (1998), 219-228.
  
  
• (with N. Monod) Bounded cohomology of lattices in higher rank Lie groups, J. Eur. Math. Soc., 1 No. 2 (1999), 199-235.
  
  
• (with N. Monod) Erratum to the above, J. Eur. Math. Soc., 1 No. 3 (1999), 338-338.
  
  
• (with S. Mozes) Groups acting on trees : from local to global structure, Publ. I.H.E.S., 92 (2000), 113-150.
  
  
• (with S. Mozes) Lattices in products of trees, Publ. I.H.E.S., 92 (2000), 151-194 (ps or pdf version).