唯一偶泛圈图的一个定理

摘要

设G是一个偶图,v是偶数且是G的阶.若对每个偶数t,4≤t≤v,G恰有一个长为t的圈,则称G是唯一偶泛圈图(简称UB-图).作者证明恰有6个v+4条边的UB-图.%A bipartite grahp G is said to be uniquely bipancyclic(G is called"UB-graph"for short)if G contains exactly one cycle of every even length t,4≤t≤v,where v is the order of G.We prove that there exist exactly six UB-graphs with v+4 edges.