A man is standing on the streets taking photographs.
Nobody is taking photos.
There was a man taking photographs, not "nobody".
exists e2 e1 x1 x2 x3.(n_street(x2) & for(e1,e2) & Theme(e2,x3) & Actor(e2,x1) & v_take(e2) & n_photograph(x3) & on(e1,x2) & Actor(e1,x1) & v_stand(e1) & n_man(x1))
-exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_take(e1) & n_photo(x2) & n_person(x1))