Commutator theory for relatively modular quasivarieties
Keith A. Kearnes, Ralph McKenzie · Transactions of the American Mathematical Society · 1992
We develop a commutator theory for relatively modular quasivarieties that extends the theory for modular varieties. We characterize relatively modular quasivarieties, prove that they have an almost-equational axiomatization and we investigate the lattice of subquasivarieties. We derive the result that every finitely generated, relatively modular quasivariety of semigroups is finitely based.