  We consider fuzzy rough sets defined on De Morgan Heyting algebras. We
present a theorem that can be used to obtain several correspondence results
between fuzzy rough sets and fuzzy relations defining them. We characterize
fuzzy rough approximation operators corresponding to compositions of reflexive,
transitive, mediate, Euclidean and adjoint fuzzy relations defined on De Morgan
Heyting algebras by using only a single axiom.
