Tail/arc-compression at threshold N/4. The previous size-30 record fits in the upper tail after translation. I explored neutral 1→1 swaps within that tail-constrained size-30 component; at another neutral state, a 1→2 exchange became available, giving this size-31 witness. All residues remain > N/4.
Yongxi (Aaron) Lin · 2026-08-09 18:23:50 UTC