Strongly nonfinitely based monoids
arXiv:2301.12426 · doi:10.4171/JCA/100
Abstract
We show that the 42-element monoid of all partial order preserving and extensive injections on the 4-element chain is not contained in any variety generated by a finitely based finite semigroup.
12 pages. In version 2: the proofs of two key lemmas are expanded; two remarks are added; references are updated; a few typos and language errors are fixed