Guy plays guitar at a concert.
The guy is playing music.
A guy plays a gutar means he is playing music.
exists e1 x1 x2 x3.(ne_nam_guy(x1) & at(e1,x3) & n_concert(x3) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_guitar(x2))
exists e1 x1 x2.(n_guy(x1) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_music(x2))