Algorithmic problems for finite groups and finite 0-simple semigroups Original Research Article

It is shown that the embeddability of a finite 4-nilpotent semigroup into a 0-simple finite semigroup with maximal groups from a pseudovariety image is decidable if and only if the universal theory of the class image is decidable. We show that it is impossible to replace 4 by 3 in this statement. We also show that if the membership in image is decidable then the membership in the pseudovariety generated by the class of all finite 0-simple semigroups with subgroups from image is decidable while the membership in the quasi-variety generated by this class of 0-simple semigroups may be undecidable.