Refinement of the biased r-wise intersection threshold conjecture

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Let nn and rr be positive integers, let [n]={1,2,…,n}[n]=\{1,2,\ldots,n\}), and let 1>p1≥p2≥⋯≥pn>01>p_1\geq p_2\geq\cdots\geq p_n>0. Write p=(p1,p2,…,pn){\bm p}=(p_1,p_2,\ldots,p_n). For a family A⊂2[n]\mathcal A\subset 2^{[n]}, let μp(A)\mu_{\bm p}(\mathcal A) denote its p{\bm p}-biased measure, and call it rr-wise intersecting if every rr members have nonempty total intersection.

Refinement of the biased rr-wise intersection threshold conjecture. The condition

r−1r>p2\frac{r-1}{r}>p_2

in the cited theorem can be replaced with

r−1r>pr+1.\frac{r-1}{r}>p_{r+1}.

In particular, the theorem holds if p4<23p_4<\frac23 instead of p3<23p_3<\frac23.

This is presented as a strengthening of a condition in an earlier theorem, rather than as an independently named result. The supplied text gives no resolution.

References

Primary source

Norihide Tokushige, “Application of hypergraph Hoffman's bound to intersecting families”, arXiv:2112.07965 (2021).

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