Hamiltonian Cycles for Finite Weyl Groupoids

Abstract

Let $\Gamma({\mathcal{W}})$ be the Cayley graph of a finite Weyl groupoid ${\mathcal{W}}$. In this paper, we show an existence of a Hamitonian cycle of $\Gamma({\mathcal{W}})$ for any ${\mathcal{W}}$. We exatctly draw a Hamiltonian cycle of $\Gamma({\mathcal{W}})$ for any (resp. some) irreducible ${\mathcal{W}}$ of rank three (resp. four). Moreover for the irreducible ${\mathcal{W}}$ of rank three, we give a second largest eigenvalue of the adjacency matrix of $\Gamma({\mathcal{W}})$, and know if $\Gamma({\mathcal{W}})$ is a bipartite Ramanujan graph or not.