Intersections of Tournaments

Source abstract

Given two tournaments of order $n$, Bollobás and Scott defined their discrepancy in terms of the extremal deviation of their overlap from the random average, after relabelling them on a common vertex set, and they asked whether the resulting discrepancy is always $Ω(n^{3/2})$. We answer this question by proving that there is an absolute constant $c>0$ such that every pair of tournaments $T,U$ of order $n$ has discrepancy at least $cn^{3/2}$.