Currently, four major functions keep me somewhat busy. I am Professor at TU Berlin, President of the Zuse Institute (ZIB), Secretary of the International Mathematical Union (IMU), and Chair of the Einstein Foundation (ESB), all with their own location, see below, and secretarial staff in Berlin. Since the largest part of my research team and administration group is located at ZIB, it is my ZIB office where I spend most of my time. If you want to reach me by phone, please try my phone number at ZIB first. E-mail is most likely the best way to contact me.

Konrad-Zuse-Zentrum für Informationstechnik Berlin (ZIB) Takustraße 7 14195 Berlin Germany	TU Berlin Institut für Mathematik Sekretariat MA 3-1 (room MA 302) Straße des 17. Juni 136 10623 Berlin Germany	Einstein Stiftung Berlin Am Gendarmenmarkt Jägerstr. 22/23 D-10117 Berlin	International Mathematical Union Secretariat Markgrafenstr. 32 D-10117 Berlin Germany
Phone: +49 (0)30-84185-210	Phone: +49 (0)30-314-23266	Phone: +49 (0)30-20370-375	Phone: +49 (0)30-20372-431
Office: +49 (0)30-84185-208   (Susanne Mittenzwey) +49 (0)30-84185-209   (Bettina Kasse)	Office: +49 (0)30-314-28478 (Claudia Ewel)	Office: +49 (0)30-20370-228 (Kerstin Albrecht) +49 (0)30-20370-375 (Dr. Marion Müller)	Office: +49 (0)30-20372-430 (Sylwia Markwardt) manager@mathunion.org
Fax: +49 (0)30-84185-269	Fax: +49 (0)30-314-29260	Fax: +49 (0)30-20370-377	Fax: +49 (0)30 20372-439
groetschel@zib.de	groetsch@math.tu-berlin.de	chair@einsteinfoundation.de	secretary@mathunion.org