  We introduce Kleene-Varlet spaces as partially ordered sets equipped with a
polarity satisfying certain additional conditions. By applying Kleene-Varlet
spaces, we prove that each regular pseudocomplemented Kleene algebra is
isomorphic to a subalgebra of the rough set regular pseudocomplemented Kleene
algebra defined by a tolerance induced by an irredundant covering. We also
characterize the Kleene-Varlet spaces corresponding to the regular
pseudocomplemented Kleene algebras satisfying the Stone identity.
