RAYMOND MORTINI, born 1958, is professor emeritus at the Université de Lorraine in Metz (France) and, since 2020, guest researcher at the University of Luxembourg, his home country. He obtained his Ph.D. (1984) and habilitation (1988) at the University of Karlsruhe (Germany) and was hired by the Université de Metz in 1995. From 2017-2020 he hold his courses at the University of Luxembourg, still being affiliated with the Université de Lorraine. His main interests lie in function theory, functional analysis, operator theory and point set topology. Currently he is in the editorial board of three Springer journals. RUDOLF RUPP, born 1960, is professor at the Nuremberg Institute of Technology, Georg-Simon-Ohm in Nuremberg, Germany. He obtained his Ph.D.(1988) and habilitation (1992) at the University of Karlsruhe (Germany), now called KIT. From 1999 until 2003 he persued a job outside the university. His research interests lie in function theory, Banach algebras and point set topology.