
596 Soft Computing and Its Applications
of view) to construct concept approximations of high quality. Searching problems for
optimal tolerance relations are NP-complete or NP-hard. However, it has been pos-
sible to develop efcient heuristics searching for relevant tolerance relation(s) that
allow extracting interesting patterns in data. The reported results are promising. A suc-
cessful realization of this approach is possible because in the rough set approach rel-
evant tolerance relations determining patterns can be extracted from the background
knowledge represented in the form of data tables. The extracted patterns can be further
fuzzyed ...