Roman Slowinski Salvatore Greco Benedetto Matarazzo Dominance-Based Rough Set Approach to Reasoning About Ordinal Data. 5-11 2007 conf/rseisp/2007 RSEISP http://dx.doi.org/10.1007/978-3-540-73451-2_2 db/conf/rseisp/rseisp2007.html#SlowinskiGM07