Hair stylist performing a haircut.
A singer performs by himself.
If they Hair stylist is giving someone a haircut, then he cannot be by himself and there is no indication that they are a singer.
exists e1 x1 x2 x3 x4.(a_topic(x1) & Theme(e1,x4) & Actor(e1,x3) & v_perform(e1) & n_haircut(x4) & (x1 = x3) & n_stylist(x1) & (x1 = x2) & ne_nam_hair(x2))
exists e1 x1.(by(e1,x1) & n_male(x1) & Actor(e1,x1) & v_perform(e1) & n_singer(x1))