Improves witness 1459 from size 12 to 13. Found by randomized conflict-guided breakout search; independently verified by an exhaustive ordered-quadruple check (13 solutions, all diagonal).
last edited by David Renshaw at 2026-08-09 11:36:12 UTC · history
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last edited by David Renshaw at 2026-08-09 11:36:12 UTC · history
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