Displaying 681 – 700 of 3198

Showing per page

Entropy of a doubly stochastic Markov operator and of its shift on the space of trajectories

Paulina Frej (2012)

Colloquium Mathematicae

We define the space of trajectories of a doubly stochastic operator on L¹(X,μ) as a shift space ( X , ν , σ ) , where ν is a probability measure defined as in the Ionescu-Tulcea theorem and σ is the shift transformation. We study connections between the entropy of a doubly stochastic operator and the entropy of the shift on the space of trajectories of this operator.

Equicontinuous families of operators generating mean periodic maps

Valentina Casarino (1999)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

The existence of mean periodic functions in the sense of L. Schwartz, generated, in various ways, by an equicontinuous group U or an equicontinuous cosine function C forces the spectral structure of the infinitesimal generator of U or C . In particular, it is proved under fairly general hypotheses that the spectrum has no accumulation point and that the continuous spectrum is empty.

Ergodic averages with generalized weights

Doğan Çömez, Semyon N. Litvinov (2006)

Studia Mathematica

Two types of weighted ergodic averages are studied. It is shown that if F = {Fₙ} is an admissible superadditive process relative to a measure preserving transformation, then a Wiener-Wintner type result holds for F. Using this result new good classes of weights generated by such processes are obtained. We also introduce another class of weights via the group of unitary functions, and study the convergence of the corresponding weighted averages. The limits of such weighted averages are also identified....

Ergodic decomposition of quasi-invariant probability measures

Gernot Greschonig, Klaus Schmidt (2000)

Colloquium Mathematicae

The purpose of this note is to prove various versions of the ergodic decomposition theorem for probability measures on standard Borel spaces which are quasi-invariant under a Borel action of a locally compact second countable group or a discrete nonsingular equivalence relation. In the process we obtain a simultaneous ergodic decomposition of all quasi-invariant probability measures with a prescribed Radon-Nikodym derivative, analogous to classical results about decomposition of invariant probability...

Ergodic properties of contraction semigroups in L p , 1 < p <

Ryotaro Sato (1994)

Commentationes Mathematicae Universitatis Carolinae

Let { T ( t ) : t > 0 } be a strongly continuous semigroup of linear contractions in L p , 1 < p < , of a σ -finite measure space. In this paper we prove that if there corresponds to each t > 0 a positive linear contraction P ( t ) in L p such that | T ( t ) f | P ( t ) | f | for all f L p , then there exists a strongly continuous semigroup { S ( t ) : t > 0 } of positive linear contractions in L p such that | T ( t ) f | S ( t ) | f | for all t > 0 and f L p . Using this and Akcoglu’s dominated ergodic theorem for positive linear contractions in L p , we also prove multiparameter pointwise ergodic and local ergodic theorems...

Ergodic theorems and perturbations of contraction semigroups

Marta Tyran-Kamińska (2009)

Studia Mathematica

We provide sufficient conditions for sums of two unbounded operators on a Banach space to be (pre-)generators of contraction semigroups. Necessary conditions and applications to positive emigroups on Banach lattices are also presented.

Currently displaying 681 – 700 of 3198