摘要
In this paper, we show that the nonorientable genus of Cm ＋ Cn, the join of two cycles Cm and Cn, is equal to [（（m-2）（n-2））/2] if m = 3, n ≡ 1 （mod 2）, or m ≥ 4, n ≥ 4, （m, n） （4, 4）. We determine that the nonorientable genus of C4 ＋C4 is 3, and that the nonorientable genus of C3 ＋Cn is n/2 if n ≡ 0 （mod 2）. Our results show that a minimum nonorientable genus embedding of the complete bipartite graph Km,n cannot be extended to an embedding of the join of two cycles without increasing the genus of the surface.
In this paper, we show that the nonorientable genus of Cm ＋ Cn, the join of two cycles Cm and Cn, is equal to [（（m-2）（n-2））/2] if m = 3, n ≡ 1 （mod 2）, or m ≥ 4, n ≥ 4, （m, n） （4, 4）. We determine that the nonorientable genus of C4 ＋C4 is 3, and that the nonorientable genus of C3 ＋Cn is n/2 if n ≡ 0 （mod 2）. Our results show that a minimum nonorientable genus embedding of the complete bipartite graph Km,n cannot be extended to an embedding of the join of two cycles without increasing the genus of the surface.
基金
Supported by National Natural Science Foundation of China(Grant No.11171114)
