On January 14, 2005, Professor Bernd Aulbach suddenly and unexpectedly passed away at the age of 57 years. The Institute for Mathematics lost a valued colleague, a respected scientist, and a popular university teacher. We are all mourning his death.

Bernd Aulbach was born in Aschaffenburg on December 23, 1947, where he also went to school and graduated with the German high school diploma (Abitur) in 1967. Subsequently, he studied mathematics with a minor in physics in Würzburg. Early on, he discovered his interest in differential equations and consequently wrote his Master's thesis with Professor H. W. Knobloch on the topic: "The Domain of Attractivity of an Asymptotically Stable Solution for Nonautonomous Periodic Differential Equations". He graduated from Würzburg with the Master's degree (Diplom) in 1973 and remained in Würzburg as a scientific assistant to the chair, Professor Knobloch, with whom he completed the Ph.D. degree in 1976 by writing a thesis also on domains of attractivity of stable periodic solutions. He spent the academic year 1978/79 as a Visiting Assistant Professor at State University of New York in Albany. From 1983 until 1986 he had a fellowship from the "Volkswagenwerk Foundation" in order to study the project "Qualitative Analysis of Nonlinear Dynamic Systems by Means of Invariant Manifolds". In the context of this project, his State Doctoral thesis (Habilitationsschrift) "Continuous and Discrete Dynamics near Manifolds of Equilibria" emerged, which also appeared as Lecture Notes published by Springer in 1984. In August 1984, he became a lecturer (Privatdozent) at the University of Würzburg. Subsequently, he was awarded a highly competitive Heisenberg Scholarship from the DFG (German Research Society), which he used to finance a longer stay at the University of California in Berkeley in 1986/87. In the year 1987, he finally accepted a position at the University of Augsburg. In the year 1970, still as a student, he married Gudrun Nöll with whom he had one daughter and two sons; the children were born in the years 1971, 1976, and 1980.

As can be inferred from the quoted topic of his first research project, his interest was devoted to the qualitative theory of dynamical systems. And though he remained faithful to this area, it was natural that the emphasis of his work shifted. His main legacy is without doubt his steady effort to regard continuous and discrete dynamics from a common point of view. This begins 1984 with his Habilitationsschrift and culminates 2001 in his presidency of the "International Society of Difference Equations". He was thereby not only concerned with a new unification of different approaches, but also with bringing together scientists who work and perform research to a large extent separately in the areas of "differential equations" and "difference equations". This effort succeeded with the "Sixth International Conference on Difference Equations", which he organized in Augsburg in 2001. Until his death, he was considerably involved with the continuation of this conference series. Hand in hand with this, one must also recognize his activity as an editor of the "Journal of Difference Equations and Applications", to which, however, his editorial activity was not limited: The journals "Differential Equations and Dynamical Systems" and "Nonlinear Dynamics and Systems Theory" are to be mentioned as well. A crucial tool to build the bridge between continuous and discrete dynamics is the "measure chain calculus", and he was probably the first one to recognize its importance: He had already put the decisive basic principles together with his Ph.D. student S. Hilger in the late Eighties. A further emphasis of his research was nonautonomous systems, which do not produce dynamical systems in the classical sense. Here as well, he emphasized the importance of only measurable time dependence, i.e., he was concerned with a unified qualitative theory for both nonautonomous differential equations and nonautonomous difference equations. At all times he was particularly open for applications.

Together with Professor Colonius he also directed the working group "Dynamics and Control of Ordinary Differential Equations" within the scope of Augsburg's Graduate School (Graduiertenkolleg) in "Nonlinear Problems in Analysis, Geometry, and Physics". This Graduate School was granted to Augsburg in 1996 by the DFG, and from the very beginning, Bernd Aulbach was its speaker. It was also mainly due to his dedicated input that the Graduate School was extended twice and thus the maximum support duration was granted. Unfortunately he was unable to see his favorite project (as he admitted) through to its completion in this year 2005.

As a scientist, Bernd Aulbach was always active and successful, which is documented by his over 60 scientific publications. His text book on "Ordinary Differential Equations", which just appeared in its second edition, is much in demand.

Professor Aulbach was a highly gifted teacher and consequently was very popular among his students. This also resulted in a higher-than-average number of graduate students. His student S. Siegmund received a renowned Emmy Noether Scholarship. Like his lectures, his presentations were characterized by extreme clarity. For this reason, he was invited to many national and international conferences, workshops, and colloquia. In order to participate, he did not hesitate to even take the longest journeys, e.g., to Vietnam, China, or India. As a colleague, Bernd Aulbach was extremely cooperative, and he never refused to serve in committees and advisory commissions. His balanced personality was esteemed, and his ideas advanced many a committee.

The Institute for Mathematics mourns the loss of a universally qualified colleague, a popular teacher, and a friend. We will remember him forever.

Hansjörg Kielhöfer, Augsburg
(translated by Martin Bohner, Rolla)