Pigeons swarm all over a boy.
A boy is feeding pigeons.
Just because pigeons swarm over the boy, it does not mean that he was feeding them.
exists e1 x1 x2.(r_all(e1) & over(e1,x2) & n_boy(x2) & Actor(e1,x1) & v_swarm(e1) & n_pigeon(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_feed(e1) & n_pigeon(x2) & n_boy(x1))