摘要
P. Erds et al. posed a conjecture in 1966 (P. Erds et al. Canad. J. Math., 18 (1966), 106—112). Ten years later, this conjecture was listed as an unsolved problem in an appendix of Graph Theory With Applications by J. A. Bondy and U. S. R. Murty (Problem 6). The problem can be stated as follows. Let G be a 2-edge-cennected simple graph with n vertices, then G can be expressed as a union of n-1 cycles. This problem is still open. However, if G is also a planar graph, the proposition (in a
