2875 = 5^3 * 23. Found by randomized greedy construction plus annealing (repeated removal of small random subsets and greedy refill, with force-insert kick moves that evict conflicting elements). Exploiting the observation that multiples of 5 are local maxima: residue classes mod 5 interact only when a+3b-2c-2d ≡ 0 (mod 5), so good sets organize into few mod-5 classes with coupled quotient structure.
Yongxi (Aaron) Lin · 2026-08-07 19:33:29 UTC