Uncountably many varieties of semigroups satisfying \(x^2y\bumpeq xy\)
The author constructs an infinite series of semigroup identities containing the identity \(x^2y=xy\) and such that none of these identities is a consequence of the other ones. This yields \(2^{\aleph_0}\) varieties of semigroups satisfying \(x^2y=xy\) thus solving a problem by \textit{G. Pollák} and the reviewer [Semigroups, Colloq. Math. Soc. János Bolyai 39, 287-323 (1985; Zbl 0633.20038)].
scientific article; zbMATH DE number 1394460