Professor Patric R. J. Östergård's home 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

• 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

Recent: Jointly with Michael Braun, Tuvi Etzion, Alexander Vardy, and Alfred Wassermann, we found the first nontrivial q-analog of a Steiner system; this was also reported elsewhere. Jointly with Leonard Soicher, we showed that there is no McLaughlin geometry.

Old: In 2004, Petteri Kaski and I showed that there are 11,084,874,829 Steiner triple systems of order 19; all of those billions of objects can be obtained here. In 2009, Olli Pottonen and I showed that there are 5983 perfect binary one-error-correcting codes of length 15.

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. and the Journal of Combinatorial Designs

Publications

Equivalence of Butson-type Hadamard matrices, P. R. J. Östergård, Journal of Algebraic Combinatorics, to appear.
Switching 3-edge-colorings of cubic graphs, J. Goedgebeur and P. R. J. Östergård, Discrete Mathematics, to appear.

Other interests