A guy wearing sunglasses is smoking.
Nobody is smoking.
A guy is at least one person, so someone is smoking.
exists e1 p1 x1 x2 x3.(exists x4.((x1 = x4) & n_smoking(x4)) & Theme(e1,x3) & Actor(e1,x2) & v_wear(e1) & n_sunglass(x3) & (x1 = x2) & n_guy(x1))
-exists p1 x1.(exists x2.((x1 = x2) & n_smoking(x2)) & n_person(x1))