A man is playing an acoustic guitar.
There is a man playing a black acoustic guitar on a stage.
Not all acoustic guitar is black. Not all man playing an acoustic guitar on a stage.
exists e1 s1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_guitar(x2) & a_acoustic(s1) & Theme(s1,x2) & n_man(x1))
exists p1 x1 e1 s1 s2 x2 x3 x4 x5.((x1 = x2) & Theme(e1,x4) & Actor(e1,x3) & v_play(e1) & on(x4,x5) & n_stage(x5) & n_guitar(x4) & a_acoustic(s2) & Theme(s2,x4) & a_black(s1) & Theme(s1,x4) & (x2 = x3) & n_man(x2))