
Consider a Cayley graph \(\text{Cay}(G,S)\) of a finite group \(G\) generated by a set \(S=S^{-1}=\{s_0,\ldots,s_{|S|-1}\}\) where \(1\notin S\). A bijection \(\omega:G\to G\) is called a complete rotation of the graph if \(\omega(1)=1\) and \(\omega(xs_i)=\omega(x)s_{i+1}\) for all \(x\in G\) and all \(i\in{\mathbb{Z}}_{|S|}\). A graph is rotational if it can be represented as a Cayley graph that admits a complete rotation. This quasi-expository paper presents various necessary and/or sufficient conditions for the existence of complete rotations. For example, \(K_n\) is rotational if and only if \(n\) is a power of a prime (Theorem 2.2). Given a finite group \(G\) generated by a set \(S\), the following are equivalent: (i) \(\text{Cay}(G,S)\) admits a complete rotation; (ii) for any presentation \(\langle S|R\rangle\) of \(G\), the free group \(F(S)\) admits an automorphism that fixes setwise the normalizer of \(R\) in \(F(S)\) and also induces a cyclic permutation of \(S\); (iii) there exists a presentation \(\langle S|R\rangle\) of \(G\) such that \(F(S)\) admits an automorphism that fixes \(R\) and also induces a cyclic permutation of \(S\) (Corollary 3.1).
regular permutation group, Computational Theory and Mathematics, Finite automorphism groups of algebraic, geometric, or combinatorial structures, generating set (of a group), Geometry and Topology, rotational, Cayley graph, complete rotation, Graphs and abstract algebra (groups, rings, fields, etc.), Theoretical Computer Science
regular permutation group, Computational Theory and Mathematics, Finite automorphism groups of algebraic, geometric, or combinatorial structures, generating set (of a group), Geometry and Topology, rotational, Cayley graph, complete rotation, Graphs and abstract algebra (groups, rings, fields, etc.), Theoretical Computer Science
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