Title: Twenty-second Annual Southern California Probability Symposium Date: Sunday, December 8, 1991 Host: UCI Organizer: Ruth Williams Program: 9:30-10:10 AM Abel Klein (UCI) Contact and percolation processes in a disordered environment 10:20-11:00 AM Richard Sowers (USC) Some new results for stochastic parabolic PDE's with white noise perturbations 11:10-11:30 AM Coffee break 11:30-12:10 AM Rajeeva Karandikar (UCSB) Invariant measures and evolution equations for Markov processes characterized via martingale problems 12:20-2:00 PM Lunch 2:00-2:40 PM Weian Zheng (UCI) Brownian motion on a non-smooth Riemannian manifold 2:50-3:30 PM Simon Tavar\'e (USC) Independent process approximations for combinatorial structures