28 research outputs found

    Monochromatic loose paths in multicolored kk-uniform cliques

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    For integers kβ‰₯2k\ge 2 and β„“β‰₯0\ell\ge 0, a kk-uniform hypergraph is called a loose path of length β„“\ell, and denoted by Pβ„“(k)P_\ell^{(k)}, if it consists of β„“\ell edges e1,…,eβ„“e_1,\dots,e_\ell such that ∣ei∩ej∣=1|e_i\cap e_j|=1 if ∣iβˆ’j∣=1|i-j|=1 and ei∩ej=βˆ…e_i\cap e_j=\emptyset if ∣iβˆ’j∣β‰₯2|i-j|\ge2. In other words, each pair of consecutive edges intersects on a single vertex, while all other pairs are disjoint. Let R(Pβ„“(k);r)R(P_\ell^{(k)};r) be the minimum integer nn such that every rr-edge-coloring of the complete kk-uniform hypergraph Kn(k)K_n^{(k)} yields a monochromatic copy of Pβ„“(k)P_\ell^{(k)}. In this paper we are mostly interested in constructive upper bounds on R(Pβ„“(k);r)R(P_\ell^{(k)};r), meaning that on the cost of possibly enlarging the order of the complete hypergraph, we would like to efficiently find a monochromatic copy of Pβ„“(k)P_\ell^{(k)} in every coloring. In particular, we show that there is a constant c>0c>0 such that for all kβ‰₯2k\ge 2, β„“β‰₯3\ell\ge3, 2≀r≀kβˆ’12\le r\le k-1, and nβ‰₯k(β„“+1)r(1+ln⁑(r))n\ge k(\ell+1)r(1+\ln(r)), there is an algorithm such that for every rr-edge-coloring of the edges of Kn(k)K_n^{(k)}, it finds a monochromatic copy of Pβ„“(k)P_\ell^{(k)} in time at most cnkcn^k. We also prove a non-constructive upper bound R(Pβ„“(k);r)≀(kβˆ’1)β„“rR(P_\ell^{(k)};r)\le(k-1)\ell r

    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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