Apart from mathematics and all that ...
1. RunningStarting running in 2008, Jan ran fifteen half marathons and seven marathons, including Athens, Berlin, Prague, Amster- dam and Rotterdam.
Current personal bests:
Jan received extensive physiotherapy since, at ManualFysion, using the NASA-developed Alter-G tredmill.
In April 2017, he was able to (slowly=1:53:49) run the Prague Half Marathon again, after an absence of three years.
2. BilliardsAlso in 2008, as a counter balance for running, Jan started playing classical billiards (carambole, three cushion).
His carambole moyenne is a very modest 1.2.
His simultaneous Belgian Trappist moyenne is about 3.0.
3. Czech language and cultureIn the academic year 1997-1998, Jan was Visiting Professor at the Mathematical Institute of the Academy of Sciences of the Czech Republic in Prague.
Since then, he became a more and more frequent visitor, and got challenged by learning the language and the habits and rich history and culture of the Czech Republic.
He also has an office in the center of Prague, where he works 2-3 times per month, collaborating with the research group in Numerical Analysis of the Czech Academy of Sciences.
4. MiscellaneousVegetarianism, cooking, reading, classical music, swimming, fitness, wining and dining.