Cancellable elements of the lattice of semigroup varieties: varieties satisfying a permutational identity of length 3

Abstract

We completely determine all semigroup varieties satisfiyng a permutational identity of length 3 that are cancellable elements of the lattice of all semigroup varieties. Using this result, we provide a series of new examples of semigroup varieties that are a modular but not cancellable elements of this lattice.

arXiv commentWe have slightly modify the formulation of the main result (the old formulation is correct, but contains some unnecessary information)