Abstract
Denote by \(\mathcal {CR}\) the variety of all completely regular semigroups with the unary operation of inversion within their maximal subgroups. Next let \(\mathcal {L}^*\) be the subvariety of \(\mathcal {CR}\) in all of whose members Green’s relation \(\mathcal {L}\) is a congruence. For an \(\cap \)-subsemilattice of subvarieties of \(\mathcal {L}^*\), we determine the lower ends of kernel, (left and right) trace, and core relations, and a basis of identities of its members with a few exceptions. The semilattice is presented by a diagram, and the results in a table.
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Assistance of Edmond Lee is deeply appreciated.
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Communicated by László Márki.
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Petrich, M. Some relations on a semilattice of varieties of completely regular semigroups. Semigroup Forum 93, 607–628 (2016). https://doi.org/10.1007/s00233-016-9817-6
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DOI: https://doi.org/10.1007/s00233-016-9817-6