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

Some sporadic results:

This is an old one: There are 11,084,874,829 Steiner triple systems of order 19; see a paper by Petteri Kaski and myself.

There are 5983 perfect binary one-error-correcting codes of length 15; see the paper.

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 co-Editor-in-Chief of the Journal of Combinatorial Designs.

My research is financed in part by the Academy of Finland.

I spent the year 1996 at the Department of Mathematics and Computing Science, Eindhoven University of Technology, the Netherlands. I spent the spring 2010 at the University of Bayreuth, Germany.

Publications

New lower bounds for the Shannon capacity of odd cycles, K. A. Mathew and P. R. J. Östergård, Designs, Codes and Cryptography, to appear.
On the domination number of 2-dimensional torus graphs, S. Crevals and P. R. J. Östergård, Utilitas Mathematica, to appear.
New lower bounds for binary constant-dimension subspace codes, M. Braun, P. R. J. Östergård, and A. Wassermann, Experimental Mathematics, to appear.
The chromatic number of the square of the 8-cube, J. I. Kokkala and P. R. J. Östergård, Mathematics of Computation, to appear.
There is no McLaughlin geometry, P. R. J. Östergård and L. H. Soicher, Journal of Combinatorial Theory. Series A, to appear.
New lower bounds on error-correcting ternary, quaternary and quinary codes, A. Laaksonen and P. R. J. Östergård, in: Proceedings of the 5th International Castle Meeting on Coding Theory and Applications, LNCS, to appear.

Other interests