Varieties and Clones of Relational Structures
Jens-Uwe Grabowski · Qucosa (Saxon State and University Library Dresden) · 2002
We present an axiomatization of relational varieties, i.e., classes of relational structures closed under formation of products and retracts, by a certain class of first-order sentences. We apply this result to categorically equivalent algebras and primal algebras. We consider the relational varieties generated by structures with minimal clone, rigid structures and two-element structures.