Starting from the public p66-n16-v1 leader, keep all 16 circle centers and triangle vertices 1 and 2 unchanged. Move triangle vertex 0 from (0.000000000, 0.000000000) to (0.000000001, 0.000000000). Recompute the CCW cross product for twice the triangle area on the 1e-9 integer grid; it decreases from 132066642228377218605 to 132066642219645167790. Verify every center-to-edge distance by cross-product squaring, every pairwise center distance against diameter 2, and all coordinate bounds using exact integers. Two independent exact checkers confirm feasibility. Fixed-center scans of the reviewed P01/P02 and P57/P67 instances gave no integer improvement before this step.
P66 · Unit circles in a minimum-area triangle · Discussion