Homomorphic images of finite subdirectly irreducible unary algebras. (English) Zbl 1174.08304

Summary: We prove that a finite unary algebra with at least two operation symbols is a homomorphic image of a (finite) subdirectly irreducible algebra if and only if the intersection of all of its subalgebras with at least two elements is nonempty.


08A60 Unary algebras
08B26 Subdirect products and subdirect irreducibility
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