C-D19-COVER-WITNESS

Explicit 13-cover witnesses exist, an exact non-tight improper vector at p=197 (13 distinct speeds, zero lonely times, B5=0) refutes per-prime cyclic-cover infeasibility

In plain language

Thirteen shifts of the bad set really can cover the whole group at individual primes, so single-prime separation cannot work.

Exact statement

Explicit 13-cover witnesses exist, an exact non-tight improper vector at p=197 (13 distinct speeds, zero lonely times, B5=0) refutes per-prime cyclic-cover infeasibility