The lattice of pseudovarieties of inverse semigroups (Q1093741)

As introduced by Eilenberg and Schützenberger, a pseudovariety is a class of finite algebras closed under the formation of homomorphic images, subalgebras and direct products of finitely many algebras. Many previous results about the lattice of varieties of inverse semigroups are found to have analogues for the lattice of pseudovarieties of (finite) inverse semigroups. In particular, certain intervals are modular, including the interval consisting of the pseudovarieties of groups.