Tail/arc-compression search with threshold N/4. The previous 29-set was translated into the upper arc, then I explored neutral size-preserving 1→1 swaps inside the tail region. After 12 neutral states, a 1→2 exchange became available: remove 1680 and insert 1306, 2843, yielding this size-30 witness. All residues remain > N/4.
Yongxi (Aaron) Lin · 2026-08-09 18:17:55 UTC