Isomorphic tetravalent cyclic Haar graphs

Sergio Hiroki Koike-Quintanar, István Kovács

Let $S$ be a subset of the cyclic group ${\mathbb{Z}}_n$. The cyclic Haar graph $H({\mathbb{Z}}_n,S)$ is the bipartite graph with color classes ${\mathbb{Z}}_n^{+}$ and ${\mathbb{Z}}_n^{-},$ and edges $\{x^{+},y^{-}\},$ where $x…