76 research outputs found

    On a problem of graph theory

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    Partitioning 3-colored complete graphs into three monochromatic cycles

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    We show in this paper that in every 3-coloring of the edges of Kn all but o(n) of its vertices can be partitioned into three monochromatic cycles. From this, using our earlier results, actually it follows that we can partition all the vertices into at most 17 monochromatic cycles, improving the best known bounds. If the colors of the three monochromatic cycles must be different then one can cover ( 3 4 − o(1))n vertices and this is close to best possible

    The Approximate Loebl-Koml\'os-S\'os Conjecture III: The finer structure of LKS graphs

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    This is the third of a series of four papers in which we prove the following relaxation of the Loebl-Komlos-Sos Conjecture: For every α>0\alpha>0 there exists a number k0k_0 such that for every k>k0k>k_0 every nn-vertex graph GG with at least (12+α)n(\frac12+\alpha)n vertices of degree at least (1+α)k(1+\alpha)k contains each tree TT of order kk as a subgraph. In the first paper of the series, we gave a decomposition of the graph GG into several parts of different characteristics. In the second paper, we found a combinatorial structure inside the decomposition. In this paper, we will give a refinement of this structure. In the forthcoming fourth paper, the refined structure will be used for embedding the tree TT.Comment: 59 pages, 4 figures; further comments by a referee incorporated; this includes a subtle but important fix to Lemma 5.1; as a consequence, Preconfiguration Clubs was change

    The approximate Loebl-Koml\'os-S\'os Conjecture II: The rough structure of LKS graphs

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    This is the second of a series of four papers in which we prove the following relaxation of the Loebl-Komlos--Sos Conjecture: For every α>0\alpha>0 there exists a number k0k_0 such that for every k>k0k>k_0 every nn-vertex graph GG with at least (12+α)n(\frac12+\alpha)n vertices of degree at least (1+α)k(1+\alpha)k contains each tree TT of order kk as a subgraph. In the first paper of the series, we gave a decomposition of the graph GG into several parts of different characteristics; this decomposition might be viewed as an analogue of a regular partition for sparse graphs. In the present paper, we find a combinatorial structure inside this decomposition. In the last two papers, we refine the structure and use it for embedding the tree TT.Comment: 38 pages, 4 figures; new is Section 5.1.1; accepted to SIDM
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