A system of classes of functions which are closed under the operations of the relevant functional system. The most important examples are systems of subalgebras of the algebra of logic, systems of finite-valued logics, of automaton mappings, of algebras of recursive functions, and various others.
[a1] | R. Pöschel, L.A. [L.A. Kaluzhnin] Kalužnin, "Funktionen- und Relationenalgebren" , Deutsch. Verlag Wissenschaft. (1979) (Translated from Russian) |