The news that our dear former colleague Dr. G.J. (Georg) Still passed away on December 15, 2023, has touched us deeply.
Georg, born in 1951 in Mülheim, studied Mathematics in Saarbrücken and Siegen, and obtained his PhD degree in 1983 from the University of Mannheim. He received the venia legendi from the University of Trier in 1990 with a Habilitation on “Defektminimierungsmethoden zur Lösung Elliptischer Eigenwertaufgaben”. After that, in 1990, Georg joined the University of Twente. He was an assistant and later an associate professor in the Discrete Mathematics and Mathematical Programming group until he reached pension age in 2017.
Georg’s research area was mathematical optimization in general, and specifically semi-infinite and parametric optimization. But his interests were broad and included work on equilibrium computation, combinatorial optimization, and applications in traffic. With Ulrich Faigle and Walter Kern, he co-authored the book “Algorithmic principles of Mathematical Programming”, which appeared in 2002; it is still used in contemporary courses. His research network was broad and included researchers in Cuba, Germany, England, Spain, Taiwan, and Türkiye.
During his 27 years at the University of Twente, Georg has taught and supervised many generations of mathematicians and engineers. He was without any doubt among the most big-hearted lecturers in mathematics. His patience with students was incredible. His patience with computers was a bit less pronounced. About once per day we heard him shouting at his desktop computer.
At the University of Twente, Georg has supervised five PhD students. Several of his former students or junior collaborators are now active as professors in several parts of the world. He was an extremely amiable colleague and person, modest, attentive, and extremely caring - a personality that everyone loved to have around.
Unfortunately, and already during his active years at the university, Georg had to fight against cancer, and this more than once. But he admirably came back, and things looked quite good for several years. Yet, in the long run, the treatments had left too much of an impact on him.
We are going to miss his modesty, his helpfulness, his humour. Our feelings of sympathy go to his wife Mady, their four children, grandchildren, family and loved ones.
On behalf of the Executive Board, staff and students of the University of Twente
Prof. Joost Kok, Dean Faculty EEMCS
Prof. Stephan van Gils, department chair of Applied Mathematics
Prof. Marc Uetz, chair Discrete Mathematics and Mathematical Programming
