A cop wearing a high-visibility vest is holding a stop sign.
A cop dressed in all black is holding a sign.
If the cop is dressed in all black, he is not wearing a high-visibility vest.
exists e2 e1 s1 x1 x2 x3 x4 x5.(Theme(e2,x4) & Actor(e2,x1) & v_hold(e2) & n_sign(x4) & of(x4,x5) & n_stop(x5) & Theme(e1,x3) & Actor(e1,x2) & v_wear(e1) & n_vest(x3) & a_high-visibility(s1) & Theme(s1,x3) & (x1 = x2) & n_cop(x1))
exists e2 e1 x1 x2 x3.(Theme(e2,x3) & Actor(e2,x1) & v_hold(e2) & n_sign(x3) & all x4.(n_black(x4) -> in(e1,x4)) & Theme(e1,x2) & v_dress(e1) & (x1 = x2) & n_cop(x1))