Convergence of moving averages of multiparameter superadditive processes.
Convergence of the averages and finiteness of ergodic power funtions in weighted L1 spaces.
Let (X, F, μ) be a finite measure space. Let T: X → X be a measure preserving transformation and let Anf denote the average of Tkf, k = 0, ..., n. Given a real positive function v on X, we prove that {Anf} converges in the a.e. sense for every f in L1(v dμ) if and only if infi ≥ 0 v(Tix) > 0 a.e., and the same condition is equivalent to the finiteness of a related ergodic power function Prf for every f in L1(v dμ). We apply this result to characterize, being T null-preserving, the finite...
Convergence of the -series for stationary sequences.
Convergence presque sûre de moyennes de sommes de Riemann
Convolutions related to q-deformed commutativity
Two important examples of q-deformed commutativity relations are: aa* - qa*a = 1, studied in particular by M. Bożejko and R. Speicher, and ab = qba, studied by T. H. Koornwinder and S. Majid. The second case includes the q-normality of operators, defined by S. Ôta (aa* = qa*a). These two frameworks give rise to different convolutions. In particular, in the second scheme, G. Carnovale and T. H. Koornwinder studied their q-convolution. In the present paper we consider another convolution of measures...
Coordinatewise decomposition, Borel cohomology, and invariant measures
Given Polish spaces X and Y and a Borel set S ⊆ X × Y with countable sections, we describe the circumstances under which a Borel function f: S → ℝ is of the form f(x,y) = u(x) + v(y), where u: X → ℝ and v: Y → ℝ are Borel. This turns out to be a special case of the problem of determining whether a real-valued Borel cocycle on a countable Borel equivalence relation is a coboundary. We use several Glimm-Effros style dichotomies to give a solution to this problem in terms of certain σ-finite measures...
Correction to An algebraic formulation of ergodic problems
Correction to : “Precompact contraction of metric uniformities and the continuity of ”
Corrigendum to the paper: “A remark on the weighted averages for superadditive processes”.
Countably piecewise expanding transformations without absolutely continuous invariant measure
Counting and convergence in ergodic theory
Courte démonstration du théorème ergodique sur-additif
Cyclic approximation of analytic cocycles over irrational rotations
Cyclic approximation of ergodic step cocycles over irrational rotations
Cyclic space isomorphism of unitary operators
We introduce a new equivalence relation between unitary operators on separable Hilbert spaces and discuss a possibility to have in each equivalence class a measure-preserving transformation.
Décomposition et classification des systèmes dynamiques
Densité des orbites des trajectoires browniennes sous l’action de la transformation de Lévy
Let Tbe a measurable transformation of a probability space , preserving the measureπ. Let X be a random variable with law π. Call K(⋅, ⋅) a regular version of the conditional law of X given T(X). Fix . We first prove that ifB is reachable from π-almost every point for a Markov chain of kernel K, then the T-orbit of π-almost every point X visits B. We then apply this result to the Lévy transform, which transforms the Brownian motion W into the Brownian motion |W| − L, where L is the local time...
Density theorems for measurable transformations
Density theorems for measurable transformations
Density-preserving homeomorphisms