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A Problem of B. Plotkin for S-Acts: Automorphisms of Categories of Free S-Acts

Yefim Katsov
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Abstract

In this paper, we prove that all automorphisms of categories of free S-acts are semi-inner, which solves a variation of a well known B. Plotkin's problem in the case of monoids. We also give a description of automorphisms of categories of finitely generated free algebras of varieties of unary algebras, and show that among varieties of unary algebras only the variety of mono-unary algebras is perfect.

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Yefim Katsov. 2006-02-06. A Problem of B. Plotkin for S-Acts: Automorphisms of Categories of Free S-Acts. https://arxiv.org/abs/math/0602103

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