Krzysztof Dembczynski Salvatore Greco Roman Slowinski Second-Order Rough Approximations in Multi-criteria Classification with Imprecise Evaluations and Assignments. 54-63 2005 conf/rsfdgrc/2005-1 RSFDGrC (1) https://doi.org/10.1007/11548669_6 db/conf/rsfdgrc/rsfdgrc2005-1.html#DembczynskiGS05