C-D18H-FIXED-M5-CLOSURE

The fixed signed degree-5 margin M5 is REFUTED, a real proper non-tight vector at p=197 has M5 = minus 20/49 < 0

In plain language

A single fixed fifth-order rule cannot certify every case, an honest counterexample drives it negative.

Exact statement

The fixed signed degree-5 margin M5 is REFUTED, a real proper non-tight vector at p=197 has M5 = minus 20/49 < 0