Abstract
Let ℰ n be the variety of all epigroups of index ≤n. We prove that, for an arbitrary natural number n, the interval [ℰ n ,ℰn+1] of the lattice of epigroup varieties contains a chain isomorphic to the chain of real numbers with the usual order and an anti-chain of the cardinality continuum.
References
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Communicated by Lev N. Shevrin.
The work was partially supported by the Russian Foundation for Basic Research (grant No. 09-01-12142) and the Federal Education Agency of the Russian Federation (project No. 2.1.1/3537).
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Skokov, D.V., Vernikov, B.M. Chains and anti-chains in the lattice of epigroup varieties. Semigroup Forum 80, 341–345 (2010). https://doi.org/10.1007/s00233-009-9196-3
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DOI: https://doi.org/10.1007/s00233-009-9196-3