On three lattices that belong to every semigroup
On tolerance relations
On tolerances on periodic semigroups
On t-semigroups.
On two papers of B.M. Schein.
On unique factorization semilattices
The class of unique factorization semilattices (UFSs) contains important examples of semilattices such as free semilattices and the semilattices of idempotents of free inverse monoids. Their structural properties allow an efficient study, among other things, of their principal ideals. A general construction of UFSs from arbitrary posets is presented and some categorical properties are derived. The problem of embedding arbitrary semilattices into UFSs is considered and complete characterizations...
On weakly commutative semigroups
On -semigroups
One element extensions of commutative semigroups
One remarkable property of the bicyclic semigroup
One simple result concerning imprimitivity relations of monoids of transformations and its applications.
One-Sided Bases of Semigroups
Onesided inverses for semigroups.
One-sided principal ideals in the direct product of two semigroups
A necessary and sufficient condition is given for a) a principal left ideal in to be equal to the direct product of the corresponding principal left ideals , b) an -class to be equal to the direct product of the corresponding -classes .
Ordered sets which support inverse semigroups : Three examples.
Orthodox bands of modules
Orthodox congruences on regular semigroups.
Orthodox semidirect products and wreath products of monoids.
Orthodox semigroups.
Orthodox semigroups whose idempotents satisfy a certain identity.