a1 IRMAR, Mathematiques Université de Rennes I-35042 Rennes Cedex, France
We study the ergodic properties of a class of dynamical systems with infinite invariant measure. This class contains skew-products of Anosov systems withd. The results are applied to the K property of skew-products and also to the ergodicity of the geodesic flow on abelian coverings of compact manifolds with constant negative curvature.
(Received July 20 1987)
(Revised January 17 1989)