``Pulling apart orthogonal groups to find continuous braids,'' Geometry/Topology Seminar, Cal Tech, Pasadena, California, March 2007
``Pulling apart orthogonal groups to find continuous braids,'' Geometry/Topology Seminar, University of Chicago, Chicago, Illinois, March 2006
``Noncrossing partitions in surprising locations,'' Séminiaire Général, Université de Bourgogne, Dijon, France, June 2005
``Artin groups and polytopes,'' Geometry and Topology seminar, Cal Tech, Pasadena, California, May 2005
``Garside-like structures for arbitrary Artin groups,'' Magnus group theory seminar, CUNY-graduate center, New York, November 2004
``The role of curvature in combintorics,'' Combinatorics seminar, M.I.T., Boston, Massachusetts, October 2003
``Garside structures for free groups (and other Artin groups),'' Topology seminar, Columbia University, New York, New York, October 2003
``Calculating curvatures in concrete complexes,'' Topology seminar, Cal Tech, Pasadena, California, March 2002
``Algorithmic aspects of nonpositive curvature,'' Group theory seminar, University of Illinois, Champagne-Urbana, Illinois, November 2001
``Calculating the curvature of concrete complexes,'' Topology seminar, The Ohio State University, Columbus, Ohio, April 2001
``Rigidity of Coxeter groups,'' Topology seminar, The Ohio State University, Columbus, Ohio, April 2001
``Rigidity of Coxeter groups,'' Topology seminar, Rice University, Houston, February 2001
``Rigidity of Coxeter groups,'' Magnus group theory seminar, CUNY-graduate center, New York, February 2001
``Rigidity of Coxeter groups,'' Topology seminar, University of Oklahoma, Norman, October 2000
``Calculating the curvature of concrete complexes,'' Topology seminar, State University of New York, Binghamton, October 2000
``Rigidity of Coxeter groups,'' Topology seminar, Vanderbilt University, Nashville, September 2000
``Normal forms for free aperiodic groups,'' Semigroup seminar, University of Porto, Porto, Portugal, November 1999
``The perimeter of 
-complexes and the coherence of groups,''
Topology Seminar, University of Porto, Porto, Portugal, November 1999
``An asymptotically sharp theorem about the coherence and local
quasiconvexity of -complexes,'' Topology Seminar, University of
Texas, Austin, November 1999
``The combinatorial Gauss-Bonnet theorem and the consequences of curvature in group theory,'' Group theory seminar, University of Nebraska, Lincoln, April 1999
``The perimeter of -complexes and the coherence of groups,''
Topology Seminar, University of California, Santa Barbara, November
1998
``The geometry and topology of Artin groups and braid groups,'' Topology Seminar, Rutgers University, Newark, New Jersey, October 1998
``General versions of small cancellation theory,'' Topology Seminar, The Ohio State University, Columbus, Ohio, February 1998
``The perimeter of 2-complexes and the coherence of groups,'' Topology Seminar, University of Michigan, Ann Arbor, Michigan, February 1998
``Braid groups, torus knots and Artin groups of large type,'' Topology Seminar, University of Texas, Austin, Texas, November 1997
``Artin groups of large type,'' Geometric Group Theory Seminar, University of California, Berkeley, California, March 1997
``A general small cancellation theory approach to the Burnside
groups,'' Geometric Group
Theory Seminar, University of California,
Berkeley, California, October 1996
``Small cancellation theory and the Burnside groups,'' Algebra Seminar, San Jose State University, April 1996
``General small cancellation theory and the Burnside groups,'' Geometric Group Theory Seminar, University of California, Berkeley, Spring 1995 (a series of three talks)
``Small cancellation theory and the Burnside groups'' Topics in Automata Theory, University of California, Berkeley, Spring 1995 (a series of two talks)