摘要Let Z be the set of all positive integers, p∈Z, Zp={z=(z1,…,zp), zj∈Z}. For any z and w∈Zp, define d(z, w)=max{|zj-wj|, 1≤j≤p}; and for any subsets V1 and V2 in Zp, define d(V1, V2)=inf {d(z, w):z∈V1.W∈V2}.
2Yi-chao CHEN & Yan-pei LIU College of Mathematics and Econometrics, Hunan University, Changsha 410082, China,Department of Mathematics, Beijing Jiaotong University, Beijing 100044, China.On the average crosscap number II: Bounds for a graph[J].Science China Mathematics,2007,50(2):292-304. 被引量:3