Parametric Lyapunov exponents

摘要

In an algebraic family of rational maps of P1, we show that, for almost every parameter for the trace of the bifurcation current of a marked critical value, the critical value is Collet-Eckmann. This extends previous results of Graczyk and swiatek in the unicritical family, using Makarov theorem. Our methods are based instead on ideas of laminar currents theory.