Search results for "Approximation operators"
showing 2 items of 2 documents
On the Measure of Many-Level Fuzzy Rough Approximation for L-Fuzzy Sets
2019
We introduce a many-level version of L-fuzzy rough approximation operators and define measures of approximation obtained by such operators. In a certain sense, theses measures characterize the quality of the resulting approximation. We study properties of such measures and give a topological interpretation of the obtained results.
Extensions and intentions in the rough set theory
1998
Abstract The approach to rough set theory proposed in this paper is based on the mutual correspondence of the concepts of extension and intension. It is different from the well-known approaches in the literature in that the upper approximations and the lower approximations of ‘unknown’ sets are considered as certain families of ‘known’ sets. This approach makes it possible to formulate necessary and sufficient conditions for the existence of operations on rough sets, which are analogous to classical operations on sets. The basic results presented in this paper, based on certain ideas of the second author, were formulated by the first author in his doctoral dissertation prepared under the su…