In Memoriam Emeritus Professor G. van Dijk
Gerrit van Dijk was born on 14th August 1939 in Kampen. He studied Mathematics in Utrecht where he also received his PhD in 1969 on the thesis ‘Spherical functions on the p-adic group PGL(2)’. His supervisor was prof. dr. T.A. Springer. The academic year 1969-1970 he spent in Princeton, at the Institute of Advanced Study. There he met Harish-Chandra, whose profound contributions to the mathematics of harmonic analysis and representation theory of Lie groups made a lasting impression and formed a great source of inspiration for Gerrit’s further mathematical work. After Princeton, he returned to Utrecht and next moved to Leiden in 1972. He was appointed lector at the Rijksuniversiteit Leiden first, followed by a professorship in 1980.
Gerrit has supervised fourteen PhD students during his appointment in Leiden till his retirement in 2004, some of them jointly with Tom Koornwinder. In the period from 1980 till the mid-90s he focused his research, together with his students, on the study of harmonic analysis on – mostly non-Riemannian – symmetric spaces of rank one. A characteristic of this topic is the occurrence of invariant eigendistributions that are not locally integrable, which distinguished this work from that of Harish-Chandra’s. It led to various mathematical challenges. The obtained explicit results for such spaces have been important and influential for the further development of this part of the field of harmonic analysis. Meanwhile, Gerrit remained interested too in p-adic harmonic analysis and finite symmetric spaces. Starting around 1995, his mathematical interests shifted towards the analysis of the Berezin transform, generalizations of it and the decomposition of associated so-called ‘canonical representations’.
On these topics he collaborated much with mathematicians from Russia, in particular with V.F. Molchanov, who visited Leiden often as guest. Gerrit dared to make the – then quite demanding – journey to Tambov, Russia, to work with him there. Notable is also the close working relationship with M. Wakayama in Japan. Besides numerous international contacts, he established also fruitful collaborations within the Netherlands, with Tom Koornwinder and Erik Thomas in particular. It resulted in a viable Dutch research community in harmonic analysis and representation theory of Lie groups that organized regularly national research meetings in this field. The great interest for the workshop at the Lorentz Center in Leiden, 23-26 August 2004, in honor of his 65th birthday, showed the appreciation for his contributions to the field, by many national and international participants from all over the world.
Many will remember Gerrit from his great contributions in various managerial roles. For example, alongside his academic work, he functioned with much elan and personal enthusiasm as scientific director of the Leiden Mathematical Institute (8 years), as Dean of the Faculty of Science of Leiden University (4 years) and as scientific director of the Leiden Institute of Advanced Computer Science (2 years). More than ten years he was involved in the management of the ‘Thomas Stieltjes Instituut voor Wiskunde’, one of the research institutes in mathematics in the Netherlands at the time, founded in 1992. He also worked as secretary to the science division of the ‘Koninklijke Hollandse Maatschappij der Wetenschappen’ in Haarlem.
Gerrit was involved in founding various new organizations. He was among the founders of the Lorentz Center in Leiden (and its first director) and the ‘European Association of Deans of Science’, of which he was also the treasurer for a while. After his valedictory lecture on 27th August 2004, Her Majesty the Queen appointed him as Officier in de Orde van Oranje-Nassau for his contributions to mathematics, science and society.
Gerrit was also interested in the history of mathematicians. He personally researched the life of Thomas Johannes Stieltjes (1856-1895), known for introducing the Stieltjes integral, in Leiden and Toulouse. He was the driving force behind the issuing of a new edition of Stieltjes’ Collected Works. At his valedictory lecture he also received a life-size replica of Snell’s quadrant, which was revealed on 16th January 2006. Until recently, it could be seen in the entry hall of the Snellius Building, in which the Mathematical Institute is housed. He also researched the former professors in Mathematics in Leiden and created as a result a portrait gallery in the Mathematical Institute. This resulted too in the publication of a book on this topic, ‘Leidse hoogleraren Wiskunde 1575-1975’, in which the lives of about forty of these professors were documented.
We will miss him dearly…