The close limit of colliding black holes: an update

This is the writeup of the talk I gave at the Yukawa International Symposium at Kyoto, Japan on June 29, 1999. The talk summarizes the present status of the close limit approximation for colliding black holes.Comment: LaTeX with PTP macros, 8 figures, 14 page

Supersymmetry, replica and dynamic treatments of disordered systems: a parallel presentation

I briefly review the three nonperturbative methods for the treatment of disordered systems -- supersymmetry, replicas and dynamics -- with a parallel presentation that highlights their connections and differences.Comment: Proceedings of the Inhomogeneous Random Systems, Cergy 2002; to appear in Journal of Markov Processes and Related Field

Examples of noncommutative manifolds: complex tori and spherical manifolds

We survey some aspects of the theory of noncommutative manifolds focusing on the noncommutative analogs of two-dimensional tori and low-dimensional spheres. We are particularly interested in those aspects of the theory that link the differential geometry and the algebraic geometry of these spaces.Comment: Survey article. Final version. To appear in the proceedings volume of the "International Workshop on Noncommutative Geometry", IPM, Tehran 200