The bulls are chasing the runners.
people chase bulls
Either the people are chasing or the bulls are chasing.
exists e1 x1 x2.(n_runner(x2) & n_bull(x1) & Theme(e1,x2) & Actor(e1,x1) & v_chase(e1))
exists s1 x1 x2 x3.(a_topic(x1) & Time(x1,x3) & n_bull(x3) & Theme(s1,x2) & a_chase(s1) & (x1 = x2) & n_people(x1))