A rock sculptor working on a rock.
A person throwing a rock in the pond.
The actions in the sentences are different: a sculptor working is not the same as a person throwing a rock
exists e1 x1 x2 x3 x4.(a_topic(x1) & on(e1,x4) & n_rock(x4) & Actor(e1,x3) & v_work(e1) & (x1 = x3) & n_sculptor(x1) & of(x1,x2) & n_rock(x2))
exists e1 x1 x2 x3 x4.(n_pond(x4) & a_topic(x1) & in(e1,x4) & Theme(e1,x3) & Actor(e1,x2) & v_throw(e1) & n_rock(x3) & (x1 = x2) & n_person(x1))