Roughness of fuzzy soft sets and related results

This paper investigates roughness of fuzzy soft sets. A pair of fuzzy soft rough approximations is proposed and their properties are given. Based on fuzzy soft rough approximations, the concept of fuzzy soft rough sets is introduced. New types of fuzzy soft sets such as full, intersection complete and union complete fuzzy soft sets are defined and supported by some illustrative examples. We obtain the structure of fuzzy soft rough sets, investigate the structure of fuzzy topologies induced by fuzzy soft sets, reveal the fact that every finite fuzzy topological space is a fuzzy soft approximation space and discuss fuzzy soft rough relations. We proved that there exists a one-to-one correspondence between the set of all fuzzy soft sets and the set of all [0,1]-valued information systems, which illustrates that we can research [0,1]-information systems by means of fuzzy soft sets.