7,344 research outputs found

    An extensive English language bibliography on graph theory and its applications

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    Bibliography on graph theory and its application

    Ramsey-nice families of graphs

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    For a finite family F\mathcal{F} of fixed graphs let Rk(F)R_k(\mathcal{F}) be the smallest integer nn for which every kk-coloring of the edges of the complete graph KnK_n yields a monochromatic copy of some FFF\in\mathcal{F}. We say that F\mathcal{F} is kk-nice if for every graph GG with χ(G)=Rk(F)\chi(G)=R_k(\mathcal{F}) and for every kk-coloring of E(G)E(G) there exists a monochromatic copy of some FFF\in\mathcal{F}. It is easy to see that if F\mathcal{F} contains no forest, then it is not kk-nice for any kk. It seems plausible to conjecture that a (weak) converse holds, namely, for any finite family of graphs F\mathcal{F} that contains at least one forest, and for all kk0(F)k\geq k_0(\mathcal{F}) (or at least for infinitely many values of kk), F\mathcal{F} is kk-nice. We prove several (modest) results in support of this conjecture, showing, in particular, that it holds for each of the three families consisting of two connected graphs with 3 edges each and observing that it holds for any family F\mathcal{F} containing a forest with at most 2 edges. We also study some related problems and disprove a conjecture by Aharoni, Charbit and Howard regarding the size of matchings in regular 3-partite 3-uniform hypergraphs.Comment: 20 pages, 2 figure

    An extensive English language bibliography on graph theory and its applications, supplement 1

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    Graph theory and its applications - bibliography, supplement

    Counting Hamilton decompositions of oriented graphs

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    A Hamilton cycle in a directed graph G is a cycle that passes through every vertex of G⁠. A Hamilton decomposition of G is a partition of its edge set into disjoint Hamilton cycles. In the late 60s, Kelly conjectured that every regular tournament has a Hamilton decomposition. This conjecture was recently settled for large tournaments by Kühn and Osthus [13], who proved more generally that every r-regular n-vertex oriented graph G (without antiparallel edges) with r=cn for some fixed c>3/8 has a Hamilton decomposition, provided n=n(c) is sufficiently large. In this article, we address the natural question of estimating the number of such decompositions of G and show that this number is n(1−o(1))cn^2⁠. In addition, we also obtain a new and much simpler proof for the approximate version of Kelly’s conjecture

    Spartan Daily, March 27, 1987

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    Volume 88, Issue 42https://scholarworks.sjsu.edu/spartandaily/7568/thumbnail.jp

    Spartan Daily, June 1, 1939

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    Volume 27, Issue 148https://scholarworks.sjsu.edu/spartandaily/2938/thumbnail.jp

    Spartan Daily, June 1, 1939

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    Volume 27, Issue 148https://scholarworks.sjsu.edu/spartandaily/2938/thumbnail.jp

    Spartan Daily, June 1, 1939

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    Volume 27, Issue 148https://scholarworks.sjsu.edu/spartandaily/2938/thumbnail.jp
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