Minimum Diameter Orientations of Km∨Kn |
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作者姓名: | MIAO Xiao-yan SUN Zhi-ren |
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作者单位: | [1]Shanghai Gaoqiao High School, Shanghai 200137, China; [2]School of Mathematics and Computer Science, Nanjing Normal University, Nanjing 210097, China |
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基金项目: | Supported by the National Natural Science Foundation of China(10671095) .Acknowledgements The authors are grateful to Professor Huang Jing of Victoria University for his useful comments and suggestions. |
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摘 要: | For a graph G, let D denote an orientation of G having minimum diameter. Define f(G) =diamD. In this paper, we concentrate on exploring the minimum diameter of Km ∨ Kn(m ≥ 1, n ≥ 1). Some special cases are known: f(Km ∨ Kn) = ∞, 2, 3, where m = landn ≥ 1, m = 2 or m ≥ 4 andn = 1, m=3 and n = 1, respectively. So we only consider the case when m ≥ 2 and n ≥ 2. The following results are obtained. (1) f(Km ∨ Kn) = 3, where m = 2, 3, n ≥ 2 and m = n = 4. (2) f(Km ∨ Kn) = 2, m where m ≥ 5 andmisodd, 2 ≤ n ≤ (m[m/2])-m. (3) f(Km ∨ Kn) = 2, whereto ≥ 4 and m≡ 0(rood4), 2 ≤ n ≤ (m m/2)-(m/2+1). (4) ](Km ∨ Kn) = 2, where m ≥ 6 and m ≡ 2(mod4), 2 ≤ n ≤ (m m/2)-m/2. (5)/(Km ∨ Kn) = 3, where m ≥ 4, n 〉 (m[m/2]).
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关 键 词: | 最小直径 定向 Km∨Kn 图论 |
文章编号: | 1002-0462(2007)03-0359-05 |
收稿时间: | 2004-12-01 |
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