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:

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, the Journal of Combinatorial Designs, and the Journal of Computational Algebra.


Here are (in pdf) some recent papers that have been accepted for publication. I also maintain a list of all my publications.

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: February 29, 2024.