Colloquium, University of Colorado, Nov. 1990. The homology of regular algebras. Algebra Seminar, University of Pennsylvania, Feb. 1991. The homology of regular algebras. Algebra Seminar, Brown University, Sep. 1991.
Geometry recapitulates arithmetic.
AMS Summer Research Conference on the Inverse Galois Problem, August 1993. Interpolation of galois branched covers. Algebra Seminar, McGill University, April 1994. Interpolation of galois branched covers. AMS Special Session on Galois Theory, Chattanooga, October 1996.