Abstract EN:

By analogy with the finite dimension case, we consider, in the first instance, the skew-products on S(\RAZ)^d\timesSO_p(\R)S. Unlike the periodic case, solved by the Floquet theorem, where every system is reductible, the quasi-periodic case is much more interesting. For example, we show that the systems are typically : - in a measure sense, reducibles ; in a topological sense, uniquely ergodic, and so, non reducibles.