An associative operator on the lattice of varieties of inverse semigroups.
An automata-theoretic approach to the study of the intersection of two submonoids of a free monoid
We investigate the intersection of two finitely generated submonoids of the free monoid on a finite alphabet. To this purpose, we consider automata that recognize such submonoids and we study the product automata recognizing their intersection. By using automata methods we obtain a new proof of a result of Karhumäki on the characterization of the intersection of two submonoids of rank two, in the case of prefix (or suffix) generators. In a more general setting, for an arbitrary number of generators,...
An easy proof of Ponizovski's theorem.
An embedding theorem for semigroups of continuous selfmaps.
An embedding theorem for weakly inverse semigroups.
An equivalence theorem for inverse semigroups.
An example of a semigroup where a D-class is a subsemigroup but not bisimple.
An example of the limit variety of semigroups.
An example of two non-isomorphic finite subdirectly irreducible bands generating the same variety of bands.
An example of two von Neumann regular rings with nonisomorphic Monta equivalent multiplicative semigroups.
An extension theorem of functionals on commutative semigroups
An introduction to -graphs, a graph-theoretic representation of natural numbers.
An investigation on hyperS-posets over ordered semihypergroups
In this paper, we define and study the hyper S-posets over an ordered semihypergroup in detail. We introduce the hyper version of a pseudoorder in a hyper S-poset, and give some related properties. In particular, we characterize the structure of factor hyper S-posets by pseudoorders. Furthermore, we introduce the concepts of order-congruences and strong order-congruences on a hyper S-poset A, and obtain the relationship between strong order-congruences and pseudoorders on A. We also characterize...
An order theoretic characterization of locally orthodox regular semigroups.
An order topology for finitely generated free monoids.
An unconventional problem in the elementary theory of numbers
Analytic and arithmetic theory of semigroups with divisor theory
Announcement of an international symposium on semigroup theory and related fields.
Another proof of a theorem of Evans.
Another semigroup characterization of the simple closed curve.