Article
Keywords:
congruence permutable semigroups; varieties of semigroups; varieties of regular $*$-semigroups; generators
Summary:
The paper contains characterizations of semigroup varieties whose semigroups with one generator (two generators) are permutable. Here all varieties of regular $*$-semigroups are described in which each semigroup with two generators is permutable.
References:
[1] Chajda I.:
A Note on permutability in vaгieties. Časopis pěst. matem. 115 (1990), 85-91.
MR 1044018
[2] Pondělíček B.:
Tolerance modular varieties of semigгoups. Czech. Math. J. 40 (115) (1990), 441-452.
MR 1065023
[3] Hamilton H.:
Permutability of congruences on commutative semigгoups. Semigгoup Foгum 10 (1975), 55-66.
MR 0387455
[5] Pondělíček B.:
On vaгieties of regular *-semigгoups. Czech. Math. J. 41 (116) (1991), 110-119.
MR 1087630
[б] Chajda I.:
Toleгance trivial algebгas and varieties. Acta Sci. Math. (Szeged) 46 (1983), 35-40.
MR 0739020