The asymptotic number of copies of ∧s\wedge_s in {∧k,∨l}\{\wedge_k,\vee_l\}-free families

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Let ∧r\wedge_r be the poset on elements a,b1,…,bra,b_1,\ldots,b_r with a<bia<b_i for every ii, and let ∨r\vee_r be its dual. For a family of posets P\mathcal P and a poset QQ, let La(n,P,Q)La(n,\mathcal P,Q) denote the maximum number of copies of QQ in a P\mathcal P-free family F⊆2[n]{\mathcal F}\subseteq 2^{[n]}. The sharp lower-bound conjecture. For any integers k,l,sk,l,s with s≤k−1s\le k-1,

La(n,{∧k,∨l},∧s)=((k−1s)l−1k+l−2+o(1))(n⌊n/2⌋).La(n,\{\wedge_k,\vee_l\},\wedge_s)=\left(\binom{k-1}{s}\frac{l-1}{k+l-2}+o(1)\right)\binom{n}{\lfloor n/2\rfloor}.

The paper proves the same expression as a lower bound by generalizing a construction of Katona and Tarján, and conjectures that this lower bound is sharp.

References

Primary source

Dániel Gerbner, Abhishek Methuku, Dániel T. Nagy, Balázs Patkós and Máté Vizer, “On the number of containments in P-free families”, arXiv:1804.01606 (2018).

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