Mercredi 24 février 2021
Loris Arnold (LmB, Université de Franche-Comté)
First we study $\gamma$-bounded -semigroups on Banach spaces. We will able to generalize Gomilko Shi-Feng Theorem in Banach settings. This generalization gives us a characterization of -bounded -semigroups. Further, in this context, we study the derivative bounded functional calculus introduced by Batty Haase and Mubeen.
Then we study operators which satisfy a condition called discrete Gomilko Shi-Feng condition. We show that this condition is equivalent to various bounded functional calculi. We also study power -bounded operators and we characterize them in a similar way as for -bounded -semigroups.
Finally, we focus on -semigroups on Hilbert space. Our goal is to construct a bounded functional calculus on a new algebra inspired by Figa-Talamanca-Herz algebras. We show that this bounded functional calculus improves existing results.