the two boys playing guitar
Two boys are sitting on the couch, playing x-box.
The boys can play either the guitar or the x-box, not both.
exists e1 x1 x2 x3.(n_boy(x1) & card_eq_2(x1) & a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_play(e1) & n_guitar(x3) & (x1 = x2))
exists e2 e1 x1 x2 x3.(n_couch(x2) & for(e1,e2) & Theme(e2,x3) & Actor(e2,x1) & v_play(e2) & n_x-box(x3) & on(e1,x2) & Actor(e1,x1) & v_sit(e1) & n_boy(x1) & card_eq_2(x1))