68 research outputs found

    Large rainbow matchings in large graphs

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    A \textit{rainbow subgraph} of an edge-colored graph is a subgraph whose edges have distinct colors. The \textit{color degree} of a vertex vv is the number of different colors on edges incident to vv. We show that if nn is large enough (namely, nβ‰₯4.25k2n\geq 4.25k^2), then each nn-vertex graph GG with minimum color degree at least kk contains a rainbow matching of size at least kk

    A generalization of heterochromatic graphs

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    In 2006, Suzuki, and Akbari & Alipour independently presented a necessary and sufficient condition for edge-colored graphs to have a heterochromatic spanning tree, where a heterochromatic spanning tree is a spanning tree whose edges have distinct colors. In this paper, we propose ff-chromatic graphs as a generalization of heterochromatic graphs. An edge-colored graph is ff-chromatic if each color cc appears on at most f(c)f(c) edges. We also present a necessary and sufficient condition for edge-colored graphs to have an ff-chromatic spanning forest with exactly mm components. Moreover, using this criterion, we show that a gg-chromatic graph GG of order nn with ∣E(G)∣>(nβˆ’m2)|E(G)|>\binom{n-m}{2} has an ff-chromatic spanning forest with exactly mm (1≀m≀nβˆ’11 \le m \le n-1) components if g(c)β‰€βˆ£E(G)∣nβˆ’mf(c)g(c) \le \frac{|E(G)|}{n-m}f(c) for any color cc.Comment: 14 pages, 4 figure

    Existences of rainbow matchings and rainbow matching covers

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    Let GG be an edge-coloured graph. A rainbow subgraph in GG is a subgraph such that its edges have distinct colours. The minimum colour degree Ξ΄c(G)\delta^c(G) of GG is the smallest number of distinct colours on the edges incident with a vertex of GG. We show that every edge-coloured graph GG on nβ‰₯7k/2+2n\geq 7k/2+2 vertices with Ξ΄c(G)β‰₯k\delta^c(G) \geq k contains a rainbow matching of size at least kk, which improves the previous result for kβ‰₯10k \ge 10. Let Ξ”mon(G)\Delta_{\text{mon}}(G) be the maximum number of edges of the same colour incident with a vertex of GG. We also prove that if tβ‰₯11t \ge 11 and Ξ”mon(G)≀t\Delta_{\text{mon}}(G) \le t, then GG can be edge-decomposed into at most ⌊tn/2βŒ‹\lfloor tn/2 \rfloor rainbow matchings. This result is sharp and improves a result of LeSaulnier and West

    Rainbow Generalizations of Ramsey Theory - A Dynamic Survey

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    In this work, we collect Ramsey-type results concerning rainbow edge colorings of graphs

    Rainbow Generalizations of Ramsey Theory - A Dynamic Survey

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    In this work, we collect Ramsey-type results concerning rainbow edge colorings of graphs
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