A pseudovariety of semigroups is join irreducible if, whenever it is contained in the complete join of some pseudovarieties, then it is contained in one of the pseudovarieties. A finite semigroup is join irreducible if it generates a join irreducible pseudovariety. New finite -trivial semigroups () are exhibited with the property that, while each is not join irreducible, the monoid is join irreducible. The monoids are the first examples of join irreducible -trivial semigroups that generate pseudovarieties that are not self-dual. Several sufficient conditions are also established under which a finite semigroup is not join irreducible. Based on these results, join irreducible pseudovarieties generated by a -trivial semigroup of order up to six are completely described. It turns out that besides known examples and those generated by and its dual monoid, there are no further examples.
@article{RSMUP_2022__147__43_0, author = {Edmond W. \hspace{1pt}H. Lee and John Rhodes and Benjamin Steinberg}, title = {On join irreducible $J$-trivial semigroups}, journal = {Rendiconti del Seminario Matematico della Universit\`a di Padova}, pages = {43--78}, volume = {147}, year = {2022}, doi = {10.4171/rsmup/90}, mrnumber = {4450783}, zbl = {1506.20089}, language = {en}, url = {http://www.numdam.org/articles/10.4171/rsmup/90/} }
TY - JOUR AU - Edmond W. H. Lee AU - John Rhodes AU - Benjamin Steinberg TI - On join irreducible $J$-trivial semigroups JO - Rendiconti del Seminario Matematico della Università di Padova PY - 2022 SP - 43 EP - 78 VL - 147 UR - http://www.numdam.org/articles/10.4171/rsmup/90/ DO - 10.4171/rsmup/90 LA - en ID - RSMUP_2022__147__43_0 ER -
%0 Journal Article %A Edmond W. H. Lee %A John Rhodes %A Benjamin Steinberg %T On join irreducible $J$-trivial semigroups %J Rendiconti del Seminario Matematico della Università di Padova %D 2022 %P 43-78 %V 147 %U http://www.numdam.org/articles/10.4171/rsmup/90/ %R 10.4171/rsmup/90 %G en %F RSMUP_2022__147__43_0
Edmond W. H. Lee; John Rhodes; Benjamin Steinberg. On join irreducible $J$-trivial semigroups. Rendiconti del Seminario Matematico della Università di Padova, Tome 147 (2022), pp. 43-78. doi : 10.4171/rsmup/90. http://www.numdam.org/articles/10.4171/rsmup/90/
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