Obituary: Johannes Boersma (1937-2004), a remarkable mathematician

Motivation: This article is a tribute to Johannes Boersma, amathematician who made an indelible impression upon all those who got to know him professionally. Yet, he never aimed to become a star among the stars. Indeed, only the relatively small group who knew him and interacted with him will be able to judge the extremely high level at which he was used to working. He deliberately kept himself out of the limelight. The joy of doing his kind ofmathematics sufficed for him. He also seemed to derive great pleasure from helping others who got stuck in their research and showing them ways on how to solve their mathematical problems. I was one of those. Below are testimonials written by some of the colleagues, peers and others who either greatly benefited from collaborating with him or were awed by the way he handled his particular brand of mathematics. The suggestion to write this tribute came from Professor Tony Rawlins of Brunel, a contributor to the special Wiener–Hopf issue (Vol. 59/4) for which this paper was originally planned. This is the kind of mathematics Boersma loved, along with the whole gamut of special functions and complex-function theory that many applied mathematicians now consider obsolete and superseded by numerics. How wrong they are, if only in view of the handling of singularities and the development of asymptotic constructs it affords! At a recent conference Prof. Rawlins spoke to me of his amazement that nothing of the kind seemed to have been done so far. Even so, the Mathematics Department in Eindhoven offered to organize a scientific conference on the occasion of Boersma’s early retirement and he refused. Had he agreed, a book of symposium proceedings might have rendered this present paper superfluous. Although Boersma probably would have frowned upon the publication of a paper like this one, in which his person features so prominently, I believe it will serve a useful purpose. It may show what a life devoted to mathematics may look like, irrespective of career prospects and political in-fighting. Whatever career he may have had came naturally. It ended prematurely, since modern academic times and the emphasis it puts on funding had caught up with him. I start with a section on testimonials written by some of Boersma’s colleagues, both in The Netherlands and outside it, who knew him and his work well. They will emphasize different aspects of his activities and persona. Clearly, there will be some duplication of views, but this is understandable and serves to emphasize those points. In a later section I will present my own views, imperfect as these may be. The growth of the scientist will be sketched and his contributions and collaborations will be put in a, hopefully, proper perspective.With only 6 weeks, the time I had for this was fairly short. But then, the Internet and e-mail communication spares one weeks and weeks in dusty library vaults. This contribution will be completed by an incomplete list of Boersma’s publications.