Endomorphisms of Cayley digraphs of rectangular groups

Abstract

Let \(\mathrm{Cay}(S,A)\) denote the Cayley digraph of the semigroup \(S\) with respect to the set \(A\), where \(A\) is any subset of \(S\). The function \(f : \mathrm{Cay}(S,A) \to \mathrm{Cay}(S,A)\) is called an endomorphism of \(\mathrm{Cay}(S,A)\) if for each \((x,y) \in E(\mathrm{Cay}(S,A))\) implies \((f(x),f(y)) \in E(\mathrm{Cay}(S,A))\) as well, where \(E(\mathrm{Cay}(S,A))\) is an arc set of \(\mathrm{Cay}(S,A)\). We characterize the endomorphisms of Cayley digraphs of rectangular groups \(G\times L\times R\), where the connection sets are in the form of \(A=K\times P\times T\).