Formation operators on classes of algebras

摘要

Let format be the formation generated by a class of algebras X. The properties of form have been studied by Shemetkov, Skiba and others since 1981. In this paper, we consider "form" as an operator acting on the set of classes of algebras and extend it to the closure operator "tau form" for some subsystem functors tau. New results are obtained and some known results are generalized. In addition, the algebras in taufortm are considered. References: 19