ТРИ ОСЛАБЛЕННЫХ ВАРИАНТА КОНГРУЭНЦ-ПЕРЕСТАНОВОЧНОСТИ ДЛЯ МНОГООБРАЗИЙ ПОЛУГРУПП

Translated title of the contribution: Three weaker variants of congruence permutability for semigroup verieties

Research output: Contribution to journalArticle

Abstract

Congruences and on an algebra A are called 2.5-permut-able if the join of and in the lattice of congruences on A coincides with the set-theoretical union of the relations and . A semigroup variety V is called almost fi-permutable [almost weakly fi-permutable, almost fi-2.5-permutable] if any two fully invariant congruences on a V-free object S permute [weakly permute, 2.5-permute] whenever these congruences are contained in the least semilattice congruence on S. We completely determine all almost fi-permutable varieties, all almost fi-2.5-permutable varieties, and almost weakly fi-permutable varieties under the additional assumption that all nilsemigroups in a variety are semigroups with zero multiplication. The first and the third of the corresponding results correct some gaps in two previous papers.
Translated title of the contributionThree weaker variants of congruence permutability for semigroup verieties
Original languageRussian
Pages (from-to)567-604
Number of pages38
JournalSiberian Electronic Mathematical Reports
Volume11
Publication statusPublished - 2014

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  • 27.17.00

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