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:
“All the old supports going, gone, this man reaches out a hand to steady himself on a ledge of rough brick that is warm in the sun: his hand feeds him messages of solidity, but his mind messages of destruction, for this breathing substance, made of earth, will be a dance of atoms, he knows it, his intelligence tells him so: there will soon be war, he is in the middle of war, where he stands will be a waste, mounds of rubble, and this solid earthy substance will be a film of dust on ruins.”
—Doris Lessing (b. 1919)
“Here did she fall a tear. Here in this place
I’ll set a bank of rue, sour herb-of-grace.
Rue even for ruth here shortly shall be seen
In the remembrance of a weeping queen.”
—William Shakespeare (1564–1616)