摘要
设r≥4且r是偶整数．阶为2n的偶图G被称为唯一r-偶泛圈图，如果对每个偶整数t，r≤t≤2n，G恰含一个长为t的圈，且G不含长小于，的圈．若G是唯一r-偶泛圈圈，则称G是r-UB-图．证明了恰好存在6个外可平面的r-UB-图和对m≤3恰好存在12个阶为2n和边数为2n＋m的r－UB－图．
Let r ≤ 4 be an even integer. A bipartite graph G if order 2n is said to be uniquely r-bipancyclic if G contains exactly one cycle of every even length t, r ≤ t ≤2n,and G contains no cycle of length less than r. If G is a uniquely r-bipancyclic graph, thenG is called an r-graph. In this paper, we prove that there exist exactly six outerplanar r-UB-graphs and exactly twelve r-UB-graphs of order 2n and size 2n + m for m ≤3.
出处
《上海师范大学学报（自然科学版）》
1997年第4期1-10,共10页
Journal of Shanghai Normal University(Natural Sciences)
关键词
圈
偶图
唯一r-偶泛圈图
cycle
bipartite graph
uniquely r-bipancyclic graph
