Matjaž Zaveršnik
Inst. of Math., Physics, and Mechanics
Dept. of Theoretical Computer Science
Jadranska 19, 1000 Ljubljana, Slovenia matjaz.zaversnik@fmf.uni-lj.si
Vladimir Batagelj
Faculty of Mathematics and Physics
Department of Mathematics
Jadranska 19, 1000 Ljubljana, Slovenia vladimir.batagelj@uni-lj.si