137 research outputs found

    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

    Flows and bisections in cubic graphs

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    A kk-weak bisection of a cubic graph GG is a partition of the vertex-set of GG into two parts V1V_1 and V2V_2 of equal size, such that each connected component of the subgraph of GG induced by ViV_i (i=1,2i=1,2) is a tree of at most k−2k-2 vertices. This notion can be viewed as a relaxed version of nowhere-zero flows, as it directly follows from old results of Jaeger that every cubic graph GG with a circular nowhere-zero rr-flow has a ⌊r⌋\lfloor r \rfloor-weak bisection. In this paper we study problems related to the existence of kk-weak bisections. We believe that every cubic graph which has a perfect matching, other than the Petersen graph, admits a 4-weak bisection and we present a family of cubic graphs with no perfect matching which do not admit such a bisection. The main result of this article is that every cubic graph admits a 5-weak bisection. When restricted to bridgeless graphs, that result would be a consequence of the assertion of the 5-flow Conjecture and as such it can be considered a (very small) step toward proving that assertion. However, the harder part of our proof focuses on graphs which do contain bridges.Comment: 14 pages, 6 figures - revised versio
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