Some results about symmetric semigroups
Lourdes Juan · Communications in Algebra · 1993
In this article we prove the equivalence of two definitions of symmetric semigroups, a necessary and sufficient condition for semigroups to be symmetric and a sufficient condition for non-symmetry of semigroups (4,b,c,c+l), b≡l, c≡2 (mod 4). An upper bound is given for the largest integer which is not in.a semigroup generated by k relative prime positive integers.