Range sets and partition sets in connection with congruences and algebraic invariants.
Ranks of binary relations.
Rational tree morphisms and transducer integer sequences: definition and examples.
Reconstructing some idempotent-generated semigroups from their biordered sets.
Reductive groups and regular semigroups.
Regular ....-classes of semigroups of continua.
Regular, inverse, and completely regular centralizers of permutations
For an arbitrary permutation in the semigroup of full transformations on a set with elements, the regular elements of the centralizer of in are characterized and criteria are given for to be a regular semigroup, an inverse semigroup, and a completely regular semigroup.
Regular monoids generated by two Galois connections.
Regularity and complete distributivity.
Regularity and Green's relations on a semigroup of transformations with restricted range.
Regularity and transitivity of local-automorphism semigroups of locally finite forests
Relations Invariant under semigroup actions.
Remarks on isomorphisms of regressive transformation semigroups.
Representable epimorphisms of monoids
Representation of inverse semigroups by local automorphisms and multi-automorphisms of groups and rings.
Representations of group and semigroup actions
Representations of semigroups by linear transformations, Part I.
Representations of semigroups by linear transformations,Part II..
Representations of semigroups of idempotents
Riemann surfaces in Stein manifolds with the Density property
We show that any open Riemann surface can be properly immersed in any Stein manifold with the (Volume) Density property and of dimension at least 2. If the dimension is at least 3, we can actually choose this immersion to be an embedding. As an application, we show that Stein manifolds with the (Volume) Density property and of dimension at least 3, are characterized among all other complex manifolds by their semigroup of holomorphic endomorphisms.