On axiomatic characterization of fuzzy approximation operators. II. The rough fuzzy set based case

In two previous papers we have developed axiomatic characterizations of approximation operators which are defined by the classical diamond and box operator of the modal logic on the one hand and are defined by the “fuzzified” diamond and box operator in applying to crisp sets, i.e. by using the concept of fuzzy rough sets on the other hand. The paper presented is a continuation of the first paper mentioned above by applying the classical diamond and box operators to fuzzy sets, i.e. by using the concepts of rough fuzzy sets