Hamiltonian decomposition of Cayley graphs of degree 4

Abstract

We prove that any 4-regular connected Cayley graph on a finite abelian group can be decomposed into two hamiltonian cycles. This answers a partial case of Alspach's conjecture concerning hamiltonian decompositions of 2k-regular connected Cayley graphs. As a corollary we obtain the hamiltonian decomposition of 2-jump circulant graphs, also called double loops.