Recent developments in the theory of skew lattices.
Rechtskomplementäre Halbgruppen, Axiome, Polynome, Kongruenzen.
Regular elements of the semigroup of all binary relations.
Regular involution groupoids revisited.
Regularity of residuated mappings.
Regularity of the wreath product of monoids.
Roots of doubly-infinite increasing sequences.
Roots of increasing sequences.