Mourning for Prof. Herbert Gajewski
(July 13, 1939 - December 11, 2019)

H. Gajewski
The Weierstrass Institute for Applied Analysis and Stochastics mourns the death of its former acting and later deputy director, research group leader and colleague, Professor Herbert Gajewski, who died unexpectedly on December 11, 2019. We bid farewell to a great individual and outstanding scientist, who has repeatedly achieved great accomplishments through the various development phases of our institute and has shaped important lines of research.

Herbert Gajewski was born on 13 July 1939 as the son of a craftsman. After graduating from high school he studied mathematics at the Humboldt Universität in Berlin, in particular under Professor Arno Langenbach, who had already developed modern functional analytical methods for the investigation of applied problems. After obtaining his diploma in 1962 Herbert Gajewski joined the Institute for Mathematics and Mechanics at the Academy of Sciences of the GDR.

Throughout his life, he was known for the high theoretical level of his research and his aspiration to solve applied problems which lead to real progress in technology and engineering. Herbert Gajewski received his doctorate in 1966 from Kurt Schröder with a thesis on “Constructive approximation methods in non-linear elasticity and plasticity theory” and habilitated with a thesis on “Direct methods for solving non-linear variation tasks and their application to problems of plasticity theory”. The theoretical foundations of this research culminated in 1974 in the monograph “Nonlinear operator equations and operator differential equations”, written jointly with Konrad Gröger and Klaus Zacharias, which still represents a widely cited standard work today.

On the other hand, he researched the optimization of chemical reactions in cooperation with Chemiewerk Schwedt for the optimization of paraffin extraction and the production of detergents from crude oil. The practical results of this work were so highly valued by the GDR that he was awarded the National Prize for Science and Technology in 1972. In 1977 Herbert Gajewski became an academy professor at the Mathematics Institute of the Academy of Sciences of the GDR.

As part of the institute's efforts to contribute to the modeling of microelectronic and optoelectronic components, the working group led by him turned to this topic. Jointly together with Konrad Gröger, he was the first person in the world to mathematically analyze the so-called van Roosbroeck system under realistic assumptions and, based on this, to develop the simulation tool “Tosca”. In the spirit of his view that work at an academy institute had to bring concrete benefits, he himself cooperated with the Funkwerk Erfurt, the semiconductor plant in Frankfurt (Oder) and the plant for television electronics in Berlin and carried out extensive calculations on the components himself. In 1993, he was awarded the Karl Heinz Beckurts Award for providing impulses for industrial innovations for his life's work in microelectronics.

From 1985 to 1992 Gajewski was a Corresponding Member of the Academy of Sciences of the GDR - since 1992 of the Berlin-Brandenburg Academy of Sciences. He played a major role in the very positive evaluation of the “Karl Weierstrass Institute” in the early post-reunification period and its re-foundation as a “Blue List Institute” in 1992, both professionally and through his exceptional personal qualities. Consequently, he also took over the function of the provisional director of this new institute until September 1993 and was, in addition to his function as head of the research group “Partial Differential Equations and Variational Equations”, also deputy director of the institute until his retirement in 2004.

In the years 1992 - 2004, he turned his attention to problems from mathematical biology and phase separation in addition to semiconductor theory and the further development of the simulation tool WIAS-TeSCA. Following his general impetus 'useful for others', the results of this research were applied in rheumatism diagnostics in cooperation with the Berlin Charité.

Herbert Gajewski was an outstanding personality as a colleague and as a person. We are very happy to have known him and to have experienced him to the end as an active honorary member of the institute. Only recently, we celebrated his 80th birthday with him at an honorary colloquium. Our thoughts are with his family in this difficult time.