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Note on Rainbow Triangles in Edge-Colored Graphs
被引:0
|作者:
Xiaozheng Chen
Xueliang Li
Bo Ning
机构:
[1] Nankai University,Center for Combinatorics and LPMC
[2] Nankai University,College of Computer Science
来源:
Graphs and Combinatorics
|
2022年
/
38卷
关键词:
Edge-coloring;
Edge-colored complete graph;
Rainbow triangle;
Color-degree condition;
05C15;
05C38;
D O I:
暂无
中图分类号:
学科分类号:
摘要:
Let G be a graph with an edge-coloring c, and let δc(G)\documentclass[12pt]{minimal}
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\begin{document}$$\delta ^c(G)$$\end{document} denote the minimum color-degree of G. A subgraph of G is called rainbow if any two edges of the subgraph have distinct colors. In this paper, we consider color-degree conditions for the existence of rainbow triangles in edge-colored graphs. At first, we give a new proof for characterizing all extremal graphs G with δc(G)≥n2\documentclass[12pt]{minimal}
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\begin{document}$$\delta ^c(G)\ge \frac{n}{2}$$\end{document} that do not contain rainbow triangles, a known result due to Li et al. Then, we characterize all complete graphs G without rainbow triangles under the condition δc(G)=log2n\documentclass[12pt]{minimal}
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\begin{document}$$\delta ^c(G)=log_2n$$\end{document}, extending a result due to Li, Fujita and Zhang. Hu, Li and Yang showed that G contains two vertex-disjoint rainbow triangles if δc(G)≥n+22\documentclass[12pt]{minimal}
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\begin{document}$$\delta ^c(G)\ge \frac{n+2}{2}$$\end{document} when n≥20\documentclass[12pt]{minimal}
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\begin{document}$$n\ge 20$$\end{document}. We slightly refine their result by showing that the result also holds for n≥6\documentclass[12pt]{minimal}
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\begin{document}$$n\ge 6$$\end{document}, filling the gap of n from 6 to 20. Finally, we prove that if δc(G)≥n+k2\documentclass[12pt]{minimal}
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\begin{document}$$\delta ^c(G)\ge \frac{n+k}{2}$$\end{document} then every vertex of an edge-colored complete graph G is contained in at least k rainbow triangles, generalizing a result due to Fujita and Magnant. At the end, we mention some open problems.
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