November 21, 2022 marks a peak in Professor Carsten Thomassen's career with the awarding of one of the most distinguished Danish scientific honours, the Ole Rømer Gold Medal. Carsten Thomassen is one of only 10 recipients of the award, which was established in 1944 on the 300th anniversary of Ole Rømer's birth.
The honorary degree was awarded in the banquet hall at the University of Copenhagen by Rector Henrik C. Wegener after the awardee had shared his enthusiasm for graph theory in a lecture and made the audience laugh and colleagues jot down scientific knowledge and jokes for their own use.
Carsten Thomassen was surprised when he heard that he was to receive the Ole Rømer Gold Medal:
"I was very touched to be nominated for the medal by DTU in the first place, but then I didn't expect to hear more. Ole Rømer was an astronomer, so the medal could go to an astronomer or anything close to astronomy, so many talented researchers could be involved. So I am very grateful for the award.”
In 2019, Carsten Thomassen was appointed Honorary Fellow of the Institute of Combinatorics and its Applications at a ceremony in Canada. It was - like the gold medal now - a peak in his career, since there can only be 10 living Honorary Fellows.
"But the Ole Rømer Gold Medal is a bit different because it is my colleagues at DTU who nominated me. It's a huge recognition, and it gives me extra energy for my research," says Carsten Thomassen.
Problem solving graph theorist
Carsten Thomassen is Professor of mathematics at DTU Compute. His field of research is combinatorics, with an emphasis on graph theory.
A graph is the mathematical abstraction for networks, such as road networks, power grids, data networks such as the Internet, and disease spread models. In computer science, graphs play a fundamental role, and graph theory has been one of the fastest growing branches of mathematics in the 20th century.
Carsten Thomassen has written over 240 publications. He has been included in the annual ISI list of the worlds 250 most cited mathematicians several times, and his work has had a great impact also in computer science. His applications of graph theory to problems in random walks, surfaces, curves, matrices, and algorithms are astonishing and original, and throughout his career he has solved several so-called "open problems" - problems that other mathematicians have had to give up on over many years.
Over the years, Thomassen has received several national and international acknowledgements, and he has been distinguished visiting professor around the world, including Rothschild Professor at the Isaac Newton Institute at Cambridge University in 2008. He is also prolific as editor of international journals, e.g., he is the main editor of the international Journal of Graph Theory since 1989.
"In the Section of Algorithms, Logic and Graphs, we consider it a privilege to have Carsten Thomassen in our midst - he has the great mathematical overview and the originality that is so important for achieving new results in the area between mathematics and IT. And he's a great teacher," says Head of Section, Professor Philip Bille.
The hunt for a beautiful mathematical proof
"It really pleases me sincerely that one of our absolute top Professors, who has also always been an excellent teacher, is now being rewarded in this way. It is an honour for our university."
Rector at DTU Anders Bjarklev
At the award ceremony, the Rector of the University of Copenhagen, Henrik C. Wegener, justified the award by saying that Carsten Thomassen is not only one of the world's leading graph theorists, but also a world-class mathematician seen across disciplines
"Carsten, you’re a great problem solver - world-renowned for your striking ability to solve very difficult problems that other mathematicians have given up on. Your scientific output is vast, and you have produced several elegant and deeply original mathematical proofs. ... The impact of your work is far-reaching. Your research has a very large application potential in other mathematical areas such as geometry and topology, and in computer science. ...All the applications are important, but I think the hunt for a beautiful mathematical proof is a goal in itself for you. What drives you and your research is of a more fundamental nature."
Words that the scientific world and colleagues can sign on to, and Carsten Thomassen himself is still fascinated by mathematics:
"Mathematics is a wonderful subject that continues to develop - it is fascinating to see how mathematics on the one hand is fundamental to many applied disciplines and on the other hand contains a wealth of beautiful problems that are interesting in themselves."
An honour for DTU
Rector at DTU Anders Bjarklev was present at the award ceremony:
"It really pleases me sincerely that one of our absolute top Professors, who has also always been an excellent teacher, is now being rewarded in this way. It is an honour for our university.”
Head of Department at DTU Compute, professor Jan Madsen, adds that the gold medal shows the importance of researchers having time for basic research.
"Today there is a lot of focus on commercialisation, and you have to be able to argue for how things can create value here and now. That is why it is super important to show the value of the fact that we actually have people who take the time and have the time to immerse themselves and look at the very basic foundations. So it's fantastic that Carsten has received this award," says Jan Madsen.
The last time the Ole Rømer Medal was awarded was in 2001 to the Physicist Lene Hau, and in 1976 it went to the Nobel laureates Aage Bohr and Ben Mottelson. Professor Carsten Thomassen is also the last recipient of the Ole Rømer Gold Medal because the foundation will be dissolved.