Claude Opus 5 has found a counterexample for Conjecture A.671 from the Aouchiche 2006 thesis, targeting its 273rd mathematical refutation. The conjecture concerns the minimum of algebraic connectivity divided by chromatic number (a/&chi;), claiming the Solt&eacute;s graph attains the bound with &chi; = &lfloor;n/2&rfloor;. At n=18, the kite graph K(18,8) beats the pinned K(18,9) by <strong>0.297%</strong>, certified exactly with the rational separator 337/65536.