On varieties of completely regular semigroups.
On varieties of completely regular semigroups II.
On varieties of completely regular semigroups III.
On Varieties of Literally Idempotent Languages
A language L ⊆A* is literally idempotent in case that ua2v ∈ L if and only if uav ∈ L, for each u,v ∈ A*, a ∈ A. Varieties of literally idempotent languages result naturally by taking all literally idempotent languages in a classical (positive) variety or by considering a certain closure operator on classes of languages. We initiate the systematic study of such varieties. Various classes of literally idempotent languages can be characterized using syntactic methods. A starting example is the...
On varieties of regular -semigroups
On varieties of regular -semigroups, II
On weakly commutative semigroups
On -operators in an arbitrary semigroup
On -ideals and generalized -ideals in 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 -ideals and -ideals in semirings.
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 .
Operators and products in the lattice of existence varieties of regular semigroups.
Operators , and in the classes of -semigroups and -semirings.
Order and domains of attraction of control sets in flag manifolds.