Axiomatizability of reducts of algebras of relations (Q1866804)

The authors study reducts of representable relation algebras whose signature contains intersection, relation composition and relation converse. They prove that the class of these algebras is a quasivariety which is non-finitely axiomatizable and its equational theory is not finitely based. The same result is shown for a class of reducts of representable cylindric algebras of dimension at least three whose similarity types include intersection and cylindrification and similarly also for the class of representable sequential algebras.