Rigidity of contractions on Hilbert spaces
arXiv:0909.4695
Abstract
We study the asymptotic behaviour of contractive operators and strongly continuous semigroups on separable Hilbert spaces using the notion of rigidity. In particular, we show that a "typical" contraction contains the unit circle times the identity operator in the strong limit set of its powers, while converges weakly to zero along a sequence with density one. The continuous analogue is presented for isometric ang unitary -(semi)groups.
17 pages. The results of this paper are published in Section IV.3 in the author's monograph "Stability of Operators and Operator Semigroups", Springer Verlag