Police officers on horses stop by a group of boys.
The police officers are yelling at the group of boys.
Stop by a group of boys does not imply yelling.
exists x1 x2 x3 x4 x5 x6.(a_topic(x1) & on(x1,x3) & by(x3,x5) & of(x5,x6) & n_boy(x6) & n_group(x5) & n_stop(x3) & of(x3,x4) & n_horse(x4) & n_officer(x1) & of(x1,x2) & n_police(x2))
exists e1 x1 x2 x3 x4.(n_group(x3) & n_officer(x1) & of(x1,x2) & n_police(x2) & at(e1,x3) & of(x3,x4) & n_boy(x4) & Actor(e1,x1) & v_yell(e1))