Professor Dr. Reinhard Mennicken was a mathematician whose research focused on differential equations and spectral theory. He received his PhD in 1963 under the supervision of Professor Dr. Friedrich Wilhelm Schaefke and his Habilitation in 1968, both at the University of Cologne, the city where he was born.

Reinhard Mennicken gained international recognition by serving as President and Vice-President of the Gesellschaft fuer Angewandte Mathematik und Mechanik (International Association of Applied Mathematics and Mechanics), GAMM, from 1993 to 1998, as President of the International Council for Industrial and Applied Mathematics, ICIAM, from 1995 to 1999, as Editor of GAMM Mitteilungen and ZAMM, and as Editor-in-Chief of Mathematische Nachrichten for 20 years from 1992 to 2011. He organized and co-organized numerous large international and national conferences, including the Annual Meetings of the GAMM in 1984 and 1997, of the Deutsche Mathematiker Vereinigung (German Mathematical Association), DMV, in 1988, the International Symposium on the Mathematical Theory of Networks and Systems, MTNS, in 1993, the International Workshop on Operator Theory and Applications, IWOTA, in 1995, all held in Regensburg with several hundreds of participants, and peaking with ICIAM 1995 in Hamburg with more than 2000 participants, jointly with Professor Dr. Oskar Mahrenholtz.

Reinhard Mennicken was also a key player in establishing fruitful collaborations with mathematicians from the former Soviet Union after the fall of the Iron Curtain in 1989 with the support of Deutsche Forschungsgemeinschaft, DFG, and Deutscher Akademischer Austauschdienst, DAAD. He attracted three Humboldt Prizes to the University of Regensburg, awarded to F.V. Atkinson, I.C. Gohberg and M.A. Krasnosel'skii.

Reinhard Mennicken had one daughter and three sons, one of whom holds a PhD in mathematics as well, and two adopted children. Academically, he had 15 PhD students; four of them hold professorships, two in Germany, one in South Africa and one in Switzerland.

My sincere thanks go to Professor Mennicken as my academic teacher, for all that I learned from him over many years since I first attended one of his seminars more than 30 years ago. Special thanks go to Dr. Marilene Balbi without whom I and many colleagues would not have learned about this loss and to Dr. Joerg Mennicken for finding this memorial site.

Christiane Tretter (Bern, Switzerland)