Professor Patric R. J. Östergård's home page
If you want to contact me,
see
this page.
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.
Research interests
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
groups:
-
Mathematical objects
- Codes (covering codes, error-correcting codes, etc.)
- Combinatorial designs
- Other structures that can be viewed as packings or coverings
-
Combinatorial algorithms
- 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
In 2004,
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
here.
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.
In 2009,
Olli Pottonen and I
showed that there are 5983 perfect binary one-error-correcting
codes of length 15.
Jointly with
Michael Braun,
Tuvi Etzion,
Alexander Vardy,
and
Alfred Wassermann,
we found the first
nontrivial q-analog of a Steiner system; the result was published in 2016 and was also reported
elsewhere.
Jointly with
Leonard Soicher, we published a result in 2018 showing
that
there is no McLaughlin geometry.
Together with
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
here.
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,
and the
Journal of Combinatorial Designs
Publications
Here are (in pdf) some recent papers that have been
accepted for publication. I also maintain a list of
all my publications.
Steiner triple systems of order 21 with subsystems,
D. Heinlein and and P. R. J. Östergård,
Glasnik Matematički. Serija III, to appear.
Bussey systems and Steiner's tactical problem,
C. J. Colbourn, D. L. Kreher, and P. R. J. Östergård,
Glasnik Matematički. Serija III, to appear.
Other interests
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: August 24, 2023.