a dog runs across the ground.
A cat chasing a rabbit.
A cat and a dog are two different animals.
exists e1 x1 x2.(n_ground(x2) & across(e1,x2) & Actor(e1,x1) & v_run(e1) & n_dog(x1))
exists e1 x1 x2 x3.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_chase(e1) & n_rabbit(x3) & (x1 = x2) & n_cat(x1))