Sur les Classes Caractéristiques des Sous-Feuilletages

Abstract

The purpose of this paper is twofold. First, we compute thé cohomology algebras H(W(g,_H_1; and second, we study some properties of subfoliations, in order to give a geometric interpretation for certain secondary characteristic classes of subfoliations, in particular, Godbillon-Vey's classes of a subfoliation. We also construct examples of subfoliations with non-trivial Godbillon-Vey classes.