ars mathematica contemporanea
Dan Archdeacon (11 May 1954 to 18 February 2015)
Professor Dan Archdeacon was a world-renowned mathematician, an intellectually engaging teacher, and a highly respected colleague. His research interests were in graph theory, combinatorics, and theoretical computer science. He published over seventy refereed papers in these fields, a majority of them in topological graph theory. His dissertation entitled "A Kuratowski Theorem for the Projective Plane" contains a proof of a ground-breaking and highly cited theorem which gives the extension of the Ku-ratowski theorem for the projective plane. This result has not been superseded.
His service to the mathematical community is widely appreciated. For over a decade, he was an editor of the Journal of Combinatorial Theory, Series B, and then he managed the offices of Journal of Graph Theory as its managing editor. He also served as a referee to over 30 journals in his field, and with Jeff Dinitz, he organised seven workshops in the Vermont Summer School on Combinatorics and Graph Theory. He started and maintained an online compendium of open problems in topological graph theory, which was an inspiration to several generations of the researchers in the field.
For most of his career, Dan taught at the University of Vermont, where he was named a University Scholar for the 2003/04 academic year. He was a Fulbright Teaching Fellow at the Riga Commerce School (Latvia), and visiting professor at the University of Auckland (New Zealand), Yokohama National University (Japan), the Technical University of Denmark, and the Open University (UK). He was an invited speaker at mathematics conferences across the globe. His talks were entertaining and always well attended.
Some of us had the privilege of working with Dan for more than two decades, on projects that resulted in many joint papers. Doing research with Dan was always a fantastic experience, both mathematically and socially. Dan was a very quick and sharp thinker. When tackling a research problem he quickly plunged into the absolute depth of the matter, but kept thinking in terms of a bigger picture of the situation at all stages. He was a true visionary, outlining avenues of research followed by others. At the same time he was a person with a great sense of humour, highly intelligent and very pleasant. He will be missed by an entire generation of scholars.
Dan visited Slovenia twice. In June 1999, he participated at the 4th Slovenian International Graph Theory Conference at Lake Bled, speaking of the representativity of planar graphs. During his second visit, in January 2014, he was already fighting cancer, but with the same optimism that he showed in his energy and passion for research. He spoke about toroidal triangulations being geometric, and initiated a problem on generalisation of Gauss words, which led to his last paper, published in this issue of Ars Mathematica Contemporanea.
Drago Bokal, Bojan Mohar, Jozef Siran
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