The inverse-linear bound for the exponent of random k-majority tournaments

From papers

Let G(n,k)\mathcal{G}(n,k) be the probability space of kk-majority tournaments on vertex set [n][n] obtained by uniformly choosing, with replacement, 2k12k-1 linear orders of [n][n]. Let X(n,k)X(n,k) be the maximum tt such that a transitive tournament TtT_t occurs in GG(n,k)G\sim\mathcal{G}(n,k), and define rkr_k as the infimum over all αR\alpha\in\mathbb{R} such that E[X(n,k)]nα\mathbb{E}[X(n,k)]\le n^\alpha for all sufficiently large nn. Inverse-linear exponent conjecture.

rk=O(1/k).r_k=O(1/k).

The bound would give a substantially stronger estimate for the expected size of the largest transitive subtournament in random kk-majority tournaments and, as noted in the source, would improve the upper bound for fk(n)f_k(n). The paper establishes rk<1r_k<1 for every kk and gives r22/3r_2\le 2/3, but the stated inverse-linear bound is not resolved here.

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Sources & referencesView supporting material

Primary source

Asaf Shapira and Raphael Yuster, “On Ramsey Properties of k-Majority Tournaments”, arXiv:2603.04174 (2026).

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