School children chase some pigeons.
Children chasing flying pigs.
The children cannot chase chickens if they are chasing pigs.
exists e1 x1 x2 x3.(Theme(e1,x3) & Actor(e1,x1) & v_chase(e1) & n_pigeon(x3) & n_child(x1) & (x1 = x2) & ne_nam_school(x2))
exists e1 x1 x2 x3 x4.(a_topic(x1) & Theme(e1,x4) & Actor(e1,x3) & v_fly(e1) & n_pig(x4) & (x1 = x3) & n_chasing(x1) & (x1 = x2) & ne_nam_children(x2))