Friday 21 January, 16:00, Zoom link
This talk is based on joint works with Bernard Helffer. Let $[0,\infty[ \ni t \to S(t)$ be a semigroup of bounded operators on a complex Hilbert space. We discuss bounds on $\|S(t)\|$ that can be obtained from bounds on the re- solvent of the generator and some known a priori bound on $\|S(t)\|$ for $t$ in a given interval $[0,a^*[$. Via variational arguments, the results are linked to second order ODE’s and Riccati equations.
Johannes Sjöstrand. (University of Burgundy, France)