An old man digs in his garden.
Nobody is digging
An old man is different from nobody.
exists s1 x1 x2 x3.(a_topic(x1) & in(x1,x3) & n_garden(x3) & of(x3,x1) & n_male(x1) & n_dig(x1) & of(x1,x2) & n_man(x2) & a_old(s1) & Theme(s1,x1))
-exists e1 x1.(Actor(e1,x1) & v_dig(e1) & n_person(x1))