We consider a class of flows which includes both magnetic flows and Gaussian thermostats of external fields. We give sufficient conditions for such flows on manifolds of negative sectional curvature to be Anosov.
I study the Schrödinger operator with the strong magnetic field, considering links between geometry of magnetic field, classical and quantum dynamics associated with operator and spectral asymptotics. In particular, I will discuss the role of short periodic trajectories.
The paper deals with the notion of entropy for doubly stochastic operators. It is shown that the entropy defined by Maličky and Riečan in [MR] is equal to the operator entropy proposed in [DF]. Moreover, some continuity properties of the [MR] entropy are established.
The invariant measures for a Markovian operator corresponding to a random walk, in a random stationary one-dimensional environment defined by a dynamical system, are quasi-invariant measures for the system. We discuss the construction of such measures in the general case and show unicity, under some assumptions, for a rotation on the circle.
Fibre expanding systems have been introduced by Denker and Gordin. Here we show the existence of a finite partition for such systems which is fibrewise a Markov partition. Such partitions have direct applications to the Abramov-Rokhlin formula for relative entropy and certain polynomial endomorphisms of ℂ².
We use the properties of to construct functions associated with the elements of the lagrangian grassmannian (n) which generalize the Maslov index on Mp(n) defined by J. Leray in his “Lagrangian Analysis”. We deduce from these constructions the identity between and a subset of , equipped with appropriate algebraic and topological structures.
Soient un groupe discret géométriquement fini d’isométries d’une variété de Hadamard pincée et une pointe de l’orbifold associé . Munissant de sa mesure de Patterson-Sullivan , nous obtenons une estimation asymptotique de la masse d’un petit voisinage horocyclique de , moyennant une hypothèse sur la croissance du sous-groupe parabolique associé à , hypothèse qui est réalisée si est symétrique de rang . Nous en déduisons une estimation asymptotique du temps de retour du flot géodésique...