An even 2-factor is one such that each cycle of length. A 4- regular graph G 4-edge-colorable if and only has two edge-disjoint 2- factors whose union contains all edges in G. It known the line a cubic without 3-edge-coloring not 4-edge-colorable. Hence, we are interested whether those graphs have an 2-factor. Bonisoli Bonvicini proved connected with number 2-factor, perfect matching [Even cycl...