FREE SYSTEMS OF ALGEBRAS AND ULTRACLOSED CLASSES
Reinhard Thron, Jörg Koppitz · 2006
Abstract. There is considered the concept of the so-called free system of algebras for an ultraclosed class of algebras of a fixed arithmetic type. Certain free systems exist for such a class if and only if the class is defined by finite disjunctions of identities where the operational symbols are interpreted as operational variables for fundamental operations of an algebra.