- October 2008 GDR Topologie Algébrique,  Université Paris 13, France.(cancelled)

- August 2008 Algebraic and Geometric Deformation Spaces, Max-Planck Institut für 
 Mathematiks, Bonn, Germany.

-Jul   Noncommutative Geometry Conference,  Hausdorff Research Institute, Bonn.

- July 2008, Mirror Symmetry, Hausdorff  Research Institute, Bonn, Germany.

- June 2008,  Homotopical Group Theory and Topological Algebraic Geometry, Max-Planck Institut für 
 Mathematiks, Bonn, Germany (60th birthday of Haynes Miller).

- June 2008,  Workshop on the Chiral de Rham Complex and Geometry, Max-Planck Institut für 
 Mathematiks, Bonn, Germany.

-October 2007 GDR Topologie Algébrique,  Université d'Angers, France.

-July 2007  Hochschild and Cylic (co)-homology and  Applications to Physics and Geometry, Max-Planck Institut für 
 Mathematiks, Bonn, Germany.

-Mathematische Arbeitstagung 2007,  Max-Planck Institut für Mathematiks, Bonn, Germany.

-June 2007 Rational Homotopy Theory, Louvain-La-Neuve, Belgium.

-January 2007 Higher Structures in Geometry and Physics, IHP, Paris, France.

-January 2006 Workshop on Moduli spaces of Knots, American Institute of Mathematics, US.

-October 2005 GDR Topologie Algèbrique, Université de Lille 1, France.

-July 2005 Annual Algebraic Topology Conference, Matsumuto, Japan.

-July 2005 Goups, Homotopy and Configuration Spaces, a conference in honor of Fred Cohen, Tokyo, Japan.

-July 2004 NATO Adavanced Study Institute: Morse theoretic methods in non-linear analysis and symplectic topology,            
 Université de Montréal, Canada.

-June 2004 GDR Topologie Algèbrique, Louvain-La-Neuve, Belgique.

-June 2004 Journées du GDR Tresses, Institut Fourier, Grenoble.

-March-June 2004 Semestre "K-théorie et géométrie noncommutative", Institut Henri Poincaré.

-August 2003 Algebraic Topology of Strings and Moduli Space of Riemann Surfaces,  SUNY Stony Brook, USA.

-March 2003 Symplectic Geometry and Physics Workshop, IPAM, UCLA, Los Angeles, USA.

-June 2002 Topological Methods in Complex Analysis and Geometry, Université de Lille.

-June 2002 Graphs and Patterns, Dennisfest SUNY, Stony Brook, USA (60th birthday of Dennis Sullivan).

-March 2002 Holomorphic Curves and Low Dimensional Topology, Institute of Advance Studies, Princeton,
 USA.

-March 2001 Around Dynamics : A Conference to Celebrate J. Milnor's 70th birthday, Stony Brook, USA.

-June 1999 Conférence en hommage à  Valentin Poenaru, Orsay, France.

-May 1999 Journal of Differential Geometry Conference in honor of Atiyah, Bott, Hirzebruch and Singer, Harvard University,  
 Boston, USA.

-April 1998 Connections in Modern Mathematics and Physics, a conference in honor of James Simon, Stony Brook, USA

- June 1998 Kirby Fest,  a conference on low dimensional topology, MSRI, Berkeley, USA.