Chains and anti-chains in the lattice of epigroup varieties

D. V. Skokov, B. M. Vernikov

Let ${\mathcal{E}}_n$ be the variety of all epigroups of index $\le n$. We prove that, for an arbitrary natural number $n$, the interval $[{\mathcal{E}}_n,{\mathcal{E}}_{n+1}]$ of the latt…