Abstract
The problem of characterization of fuzzy relational equations with respect to their solvability property is studied. Some aspects of manipulation of fuzzy data with the aid of fuzzy relational equations are considered. Two stages of manipulation process are indicated: combining pieces of evidence and inferring their mutual correspondence. Both of them are formulated and solved by the use of fuzzy relational equations. The role of a solvability index is extensively studied. Numerical considerations give an illustration of the approach we propose and deal with some real data used for fuzzy controllers.