These three volumes (Astérisque 49,50,51) contain contributions to the confe­ rence on dynamical systems and ergodic theory held at Warsaw from June 27 to
July 2, 1977, organized jointly by the mathematics institutes of the University of Rennes and the University of Warsaw. Funds for the conference were provided by the respective institutes, their universities and by the C.N.R.S. The organizers are indebted to these institutions for their generous support.

Ninety five specialists from 13 different countries participated in the lectures and discussions. The main purpose of such a conference is of course to establish contacts and create a favorable atmosphere for discussion among scientists with varied interests and from different countries, and we would like to thank all participants for their part in attaining this goal.