Race model inequality ($F_{AV}(t)\le \min (1,F_A(t)+F_V(t))$)

Under context-invariant channel distributions, $P(\min (T_A,T_V)\le t)=P(T_A\le t\mathrm{or}{T}_V\le t)\le F_A(t)+F_V(t)$ by the union bound; probability is also at most one. No independence assumption is needed. A reliable violation rejects this model with those marginals, not every possible separate-channel or decision account.