In this paper, we show that CLn, the chain with n elements, is efficient and that the direct
product CLm× CLn is inefficient. Moreover, we embed any finitely presented semigroup S …

In this thesis we consider in detail the following two problems for semigroups:(i) When are
semigroups finitely generated and presented?(ii) Which families of semigroups can be …

Let Sl denote the class of all finite semilattices and let Sl n be the pseudovariety of
semigroups generated by all semidirect products of n finite Semilattices. The main result of …

FINITE PRESENTABILITY OF SEMIGROUP CONSTRUCTIONS Page 1 April 5, 2002 17:2
WSPC/132-IJAC 00089 International Journal of Algebra and Computation, Vol. 12, Nos. 1 & 2 …

S is said to be efficient if it can be defined by a presentation (A| R) with| R|-| A|= rank (H 2
(S)). In this paper we demonstrate certain infinite classes of both efficient and inefficient …

We consider the relationship between the combinatorial properties of semigroupoids in
general and semigroups in particular. We show that a semigroupoid is finitely generated …

Abstract Let\(I\) be a semilattice, and\(S_i\)\((i\in I)\) be a family of disjoint semigroups. Then
we prove that the strong semilattice\(S=\mathcal {S}[I, S_i,\phi _ {j, i}]\) of semigroups\(S_i\) …

We study the structure of strongly 2-chained semigroups, which can be defined alternatively
as semigroups whose regular elements are completely regular. The main result is a …

We study properties determined by idempotents in the following families of matrix
semigroups over a semiring S: the full matrix semigroup M n (S), the semigroup UT n (S) …

A regular semigroup is weakly generated by a set X if it has no proper regular subsemigroup
containing X. In this paper, we study the regular semigroups weakly generated by …