1. Maria Curie-Skłodowska University, Department of Logic and Philosophy of Science, Pl. Marii Curie-Skłodowskiej 4, 20-031 Lublin, Poland. marcin.wolski@umcs.lublin.pl
2. Białystok University, Institute of Computer Science, Sosnowa 64, 15-887 Białystok, Poland. anna.gom@math.uwb.edu.pl