Order-7 CNF refutation for a Conway 99-graph encoding (CaDiCaL 1.9.5)

CaDiCaL 1.9.5 refuted conway_z7_canonical.cnf (header: p cnf 177097 422508) with verdict s UNSATISFIABLE after 58054.87 s process time on 24 September 2026. drat-trim checked proof_z7_canonical.drat (26746488053 bytes) and recorded s VERIFIED after 103482.837 s on 26 September 2026. SHA-256 sums are in SHA256SUMS.txt. This deposit is a certificate for that formula. It does not include the 10 September 2026 run (CaDiCaL 3.0.1, p cnf 176613 421562). It does not certify that every graph with a Z7 action satisfies this CNF, and it is not the CP-SAT model of Thakkar and Severini, arXiv:2608.11211.