Abstract
The question of persistence consists in trying to calculate how the probability that a stochastic quantity does not change sign until the instant t decreases. The seminar began with a presentation of theoretical examples (random walk, domain growth) and experimental situations (blast figures, liquid crystals, vicinal surfaces) for which persistence exponents have been measured. The seminar continued with a description of the theoretical approaches (exact calculations, approximations, links with random polynomials) used to determine these persistence exponents, before presenting a series of recent results on persistence in the case of the diffusion equation in dimension 2.
