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Uniformly ergodic A-contractions on Hilbert spaces

100%

Suciu L.

Studia Mathematica

2009

tom 194

nr 1

1-22

We study the concept of uniform (quasi-) A-ergodicity for A-contractions on a Hilbert space, where A is a positive operator. More precisely, we investigate the role of closedness of certain ranges in the uniformly ergodic behavior of A-contractions. We use some known results of M. Lin, M. Mbekhta and J. Zemánek, and S. Grabiner and J. Zemánek, concerning the uniform convergence of the Cesàro means of an operator, to obtain similar versions for A-contractions. Thus, we continue the study of A-ergodic operators developed earlier by the author.

Decompositions and asymptotic limit for bicontractions

63%

Kosiek M., Suciu L.

Annales Polonici Mathematici

2012

tom 105

nr 1

43-64

The asymptotic limit of a bicontraction T (that is, a pair of commuting contractions) on a Hilbert space 𝓗 is used to describe a Nagy-Foiaş-Langer type decomposition of T. This decomposition is refined in the case when the asymptotic limit of T is an orthogonal projection. The case of a bicontraction T consisting of hyponormal (even quasinormal) contractions is also considered, where we have $S_{T*}=S²_{T*}$.

Ograniczanie wyników

1 Annales Polonici Mathematici

1 Studia Mathematica

2 Suciu L.

1 Kosiek M.

1 2012

1 2009

Wyniki wyszukiwania

Uniformly ergodic A-contractions on Hilbert spaces

Decompositions and asymptotic limit for bicontractions