Optimal error estimates in operator-norm approximations of some semi-groups

Analysis Seminar
Wednesday, March 14, 2012 - 2:00pm for 1 hour (actually 50 minutes)
Skiles 006
Vygantas Paulauskas – Vilnius University
Michael Lacey
In the talk some problems related with the famous Chernoff square root of n - lemma in the theory of approximation of some semi-groups of operators will be discussed. We present some optimal bounds in these approximations (one of them is Euler approximation) and two new classes of operators, generalizing sectorial and quasi-sectorial operators will be introduced. The talk is based on two papers [V. Bentkus and V. Paulauskas, Letters in Math. Physics, 68, (2004), 131-138] and [V. Paulauskas, J. Functional Anal., 262, (2012), 2074-2099]