Loris Arnold
(Université de Franche-Comté)
Let be a bounded operator on a Banach space . We say that is a (-)Ritt operator if it satisfies that the two sequence and are (-)bounded. It is possible to construct a Ritt operator which is not -Ritt, but until now, without knowing whether or (or both) is not -bounded. We will give some preliminaries about the topic and we will construct a Ritt operator such that the sequence is not -bounded.