On free products of completely regular semigroups
Peter R. Jones · Journal of the Australian Mathematical Society Series A Pure Mathematics and Statistics · 1994
Abstract The free product*CRSiof an arbitrary family of disjoint completely simple semigroups {Si}i∈i, within the variety CR of completely regular semigroups, is described by means of a theorem generalizing that of Kaďourek and Polák for free completely regular semigroups. A notable consequence of the description is that all maximal subgroups of*CRSiare free, except for those in the factorsSithemselves. The general theorem simplifies in the case of free CR-products of groups and, in particular, free idempotent-generated completely regular semigroups.