Rough Approximations under Level Fuzzy Sets
The combination of fuzzy set and rough set theories lead to various models. Functional and set approaches are two categories based on different fuzzy representations. In this paper, we study rough approximations based on the notion of level fuzzy sets. Two rough approximation models, namely α-level rough set and β-level rough set, are proposed. It shows that β-level fuzzy rough set model can approximate a fuzzy set at different precisions.
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