Publication details

Representations of relatively free profinite semigroups, irreducibility, and order primitivity

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Authors

ALMEIDA Jorge KLÍMA Ondřej

Year of publication 2020
Type Article in Periodical
Magazine / Source Transactions of the American Mathematical Society
MU Faculty or unit

Faculty of Science

Citation
Web https://doi.org/10.1090/tran/7951
Doi http://dx.doi.org/10.1090/tran/7951
Keywords Pseudovariety; relatively free profinite semigroup; torsion; group mapping semigroup; minimum ideal; join irreducibility; ordered semigroup
Description We establish that, under certain closure assumptions on a pseudovariety of semigroups, the corresponding relatively free profinite semigroups freely generated by a nonsingleton finite set act faithfully on their minimum ideals. As applications, we enlarge the scope of several previous join irreducibility results for pseudovarieties of semigroups, which turn out to be even join irreducible in the lattice of pseudovarieties of ordered semigroups, so that, in particular, they are not generated by proper subpseudovarieties of ordered semigroups. We also prove the stronger form of join irreducibility for the Krohn-Rhodes complexity pseudovarieties, thereby solving a problem proposed by Rhodes and Steinberg.
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