Problems / combinatorics
combinatorics / Extremal combinatorics; property testing
The polynomial removal conjecture for ordered binary matrices
Theorem 1.1: there is a fixed binary 66×66 matrix H such that for every h≥1, with nh=(386h+2)2h and ϵh=(386h+2)−2, some Ah is ϵh-far from H-free yet NH(Ah)≤ϵh2−hnh132; hence no polynomial removal bound holds for this H, and the finite-family question fails for one square pattern. Corollary: canonical row-column sampling testers need exp(Ω(ϵ−1/2)) samples along this sequence. Not shown: which patterns do admit polynomial removal, or a counterexample smaller than 66×66.