In computer science, a rough set, first described by a Polish computer scientist Zdzisław I. Pawlak, is a formal approximation of a crisp set (i.e., conventional set) in terms of a pair of sets which give the lower and the upper approximation of the original set. In the standard version of rough set theory (Pawlak 1991), the lower- and upper-approximation sets are crisp sets, but in other variations, the approximating sets may be fuzzy sets.
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Famous quotes containing the words rough and/or set:
“What opium is instilled into all disaster? It shows formidable as we approach it, but there is at last no rough rasping friction, but the most slippery sliding surfaces. We fall soft on a thought.”
—Ralph Waldo Emerson (1803–1882)
“To divide one’s life by years is of course to tumble into a trap set by our own arithmetic. The calendar consents to carry on its dull wall-existence by the arbitrary timetables we have drawn up in consultation with those permanent commuters, Earth and Sun. But we, unlike trees, need grow no annual rings.”
—Clifton Fadiman (b. 1904)