Professor Patric R. J. Östergård's home page
If you want to contact me,
The University of Pécs conferred the degree of
"Doctor et Professor Honoris Causa" on me
at a ceremony held in Pécs, Hungary, on 7 November 2013.
I am interested in a wide variety of problems in mathematics,
telecommunications, and computer science. In particular, I am interested in
using computers to find and classify mathematical objects.
My research themes can roughly be divided into the following
- Codes (covering codes, error-correcting codes, etc.)
- Combinatorial designs
- Other structures that can be viewed as packings or coverings
- Stochastic optimization methods, local search algorithms (tabu search)
- Exact algorithms for (NP-)hard problems
- Graph algorithms for clique and coloring problems
- Algorithms for isomorphism testing; classification algorithms
Information theory, in general
Discrete mathematics, in general
Recent and old news
Petteri Kaski and I showed that there are
11,084,874,829 (isomorphism classes of) Steiner triple systems
of order 19; all of those billions of objects can be obtained
For orders greater than 19, there will be too many to
classify and save all of them. Anyway, in 2023,
Daniel Heinlein and I counted the Steiner triple systems of
order 21; the number is 14,796,207,517,873,771.
Olli Pottonen and I
showed that there are 5983 perfect binary one-error-correcting
codes of length 15.
we found the first
nontrivial q-analog of a Steiner system; the result was published in 2016 and was also reported
Leonard Soicher, we published a result in 2018 showing
there is no McLaughlin geometry.
Sampo Niskanen, we have developed Cliquer, routines
for clique searching. The first public release (1.0) was
made in late 2002; the current release (1.21) can be found
I am a recipient of the 1996 Kirkman Medal, awarded by
the Institute of Combinatorics and its Applications.
I am on the editorial boards of the
Bulletin of the Institute of
Combinatorics and its Applications,
Designs, Codes and Cryptography,
Journal of Combinatorial Designs
Here are (in pdf) some recent papers that have been
accepted for publication. I also maintain a list of
all my publications.
A marathon race takes only a
little bit more than 2 hours for the elite. That is far from
being a real endurance sport. You have to increase the
running distance beyond 100k to find out who really has
endurance. I have myself taken part in marathons in different
sports. I maintain a list of
all marathons that I have completed. For other sports
than running, I have listed events that are at least 50k.
Latest update: December 11, 2023.