Finite Semigroups Satisfying an Identity $x_1 \dots x_n \approx \rho(x_1, \dots, x_n)$

Abstract

We determine the maximal pseudovarieties of finite semigroups that satisfy an identity of the form $x_1 \dots x_n \approx \rho(x_1, \dots, x_n)$. Applying this classification, we further show that a pseudovariety of permutative semigroups satisfies a common permutation identity if and only if it satisfies an identity of the above form or, equivalently, if it does not contain $\mathbf{T} = [x^2 \approx xyx \approx 0]$.