15,628 research outputs found

    Low-distortion embeddings of graphs with large girth

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    The main purpose of the paper is to construct a sequence of graphs of constant degree with indefinitely growing girths admitting embeddings into â„“1\ell_1 with uniformly bounded distortions. This result answers the problem posed by N. Linial, A. Magen, and A. Naor (2002).Comment: Some confusing omissions are corrected in the second versio

    Local colourings and monochromatic partitions in complete bipartite graphs

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    We show that for any 22-local colouring of the edges of the balanced complete bipartite graph Kn,nK_{n,n}, its vertices can be covered with at most~33 disjoint monochromatic paths. And, we can cover almost all vertices of any complete or balanced complete bipartite rr-locally coloured graph with O(r2)O(r^2) disjoint monochromatic cycles.\\ We also determine the 22-local bipartite Ramsey number of a path almost exactly: Every 22-local colouring of the edges of Kn,nK_{n,n} contains a monochromatic path on nn vertices.Comment: 18 page
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