Closures of regular languages for profinite topologies.
The Pin-Reutenauer iterative descriptive procedure to compute the closure in the free group of a regular language with respect to the Hall topology is shown to hold also for several pseudovarieties of finite semigroups: for the pseudovarieties of finite aperiodic semigroups, of finite semigroups in which all regular elements are idempotents, of finite \(\mathcal J\)-trivial semigroups, of finite local semilattices and of finite \(\mathcal R\)-trivial semigroups.
scientific article; zbMATH DE number 6363654
scientific article