A man sits behind a music stand playing the guitar while people perform in the background.
The man is playing a rock song.
Just because the man is playing the guitar, it doesn't mean that he is playing a rock song.
exists e1 e2 p1 x1 x2 x3 x4 x5 x7.(n_background(x7) & n_guitar(x5) & behind(e1,x2) & exists e3 x6.(in(e3,x7) & Actor(e3,x6) & v_perform(e3) & n_people(x6)) & while(e2,p1) & Theme(e2,x5) & Actor(e2,x4) & v_play(e2) & (x2 = x4) & n_stand(x2) & of(x2,x3) & n_music(x3) & Actor(e1,x1) & v_sit(e1) & n_man(x1))
exists e1 x1 x2 x3.(n_man(x1) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_song(x2) & of(x2,x3) & n_rock(x3))