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Union-closed families with small average overlap densities - MaRDI portal

Union-closed families with small average overlap densities (Q2073302)

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Union-closed families with small average overlap densities
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    Union-closed families with small average overlap densities (English)
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    1 February 2022
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    Summary: In this very short paper, we show that the average overlap density of a union-closed family \(\mathcal{F}\) of subsets of \(\{1,2,\ldots,n\}\) may be as small as \[\Theta((\log_2 \log_2 |\mathcal{F}|)/(\log_2 |\mathcal{F}|)),\] for infinitely many positive integers \(n\).
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    union-closed conjecture
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    average overlap density
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