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arXiv · 2209.13867

Rainbow Subgraphs in Edge-colored Complete Graphs -- Answering two Questions by Erdős and Tuza

Maria Axenovich·Felix Christian Clemen
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Abstract

An edge-coloring of a complete graph with a set of colors $C$ is called completely balanced if any vertex is incident to the same number of edges of each color from $C$. Erdős and Tuza asked in $1993$ whether for any graph $F$ on $\ell$ edges and any completely balanced coloring of any sufficiently large complete graph using $\ell$ colors contains a rainbow copy of $F$. This question was restated by Erdős in his list of ``Some of my favourite problems on cycles and colourings''. We answer this question in the negative for most cliques $F=K_q$ by giving explicit constructions of respective completely balanced colorings. Further, we answer a related question concerning completely balanced colorings of complete graphs with more colors than the number of edges in the graph $F$.

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Maria Axenovich, Felix Christian Clemen. 2022-11-28. Rainbow Subgraphs in Edge-colored Complete Graphs -- Answering two Questions by Erdős and Tuza. https://arxiv.org/abs/2209.13867

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