A man rests a silver-colored metal disk on a rock surface as he works on the back side of it.
A man is a geologist.
A man resting a silver-colored metal disk on a rock surface is not necessarily a geologist.
exists e1 p1 s1 s2 x1 x2 x3 x4 x5 x6.(n_side(x6) & a_back(s2) & Theme(s2,x6) & exists e2.(on(e2,x6) & of(x6,x1) & Actor(e2,x1) & v_work(e2)) & n_thing(x1) & n_male(x1) & as(e1,p1) & Theme(e1,x2) & Actor(e1,x1) & v_rest(e1) & on(x2,x4) & n_surface(x4) & of(x4,x5) & n_rock(x5) & n_disk(x2) & of(x2,x3) & n_metal(x3) & a_silver-colored(s1) & Theme(s1,x2) & n_man(x1))
exists p1 x1.(exists x2.((x1 = x2) & n_geologist(x2)) & n_man(x1))