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Articolul precedent |
Articolul urmator |
735 5 |
Ultima descărcare din IBN: 2022-12-04 15:31 |
SM ISO690:2012 GIGON, Roman. Clifford congruences on perfect semigroups. In: Quasigroups and Related Systems, 2013, vol. 21, nr. 2(30), pp. 207-228. ISSN 1561-2848. |
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Quasigroups and Related Systems | ||||||
Volumul 21, Numărul 2(30) / 2013 / ISSN 1561-2848 | ||||||
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Pag. 207-228 | ||||||
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A congruence on a semigroup S is called perfect if (a)(b) = (ab) for all a; b 2 S, as sets, and a semigroup S is said to be -idempotent-surjective (respectively perfect) if every -class of S contains an idempotent of S, where is the least semilattice congruence on S (respectively if each congruence on S is perfect). We describe the least Clifford congruence on an -idempotent-surjective perfect semigroup S. In addition, a characterization of all Clifford congruences on such a semigroup is given.Furthermore, we find necessary and sufficient conditions for to be idempotent pure or E-unitary. Moreover, we give a full description of all USG-congruences on an-idempotent-surjective perfect semigroup S. In fact, we show that each USG-congruence # on S is the intersection of a semilattice congruence " and a group congruence (and vice versa), and this expression is unique. Also, S=# = S=" S=. Finally, we investigate the lattice of Clifford congruences on a semigroup S which is a semilattice S= of E-inversive semigroups e (e 2 ES). |
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Cuvinte-cheie Clifford congruence, USG-congruence, perfect semigroup, -idempotent-surjective semigroup, group (semilattice) congruence, idempotent pure congruence |
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