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Varieties of many-sorted recognizable sets. (English) Zbl 1224.68056

Summary: We consider varieties of recognizable subsets of many-sorted finitely generated free algebras over a given variety, varieties of congruences of such algebras, and varieties of finite many-sorted algebras. A variety theorem that establishes bijections between the classes of these three types of varieties is proved. For this, appropriate notions of many-sorted syntactic congruences and algebras are needed. Also an alternative type of varieties is considered where each subset consists of elements of just one sort.

MSC:

68Q70 Algebraic theory of languages and automata
08A70 Applications of universal algebra in computer science
08B15 Lattices of varieties
08A68 Heterogeneous algebras