Musician sings into a microphone while playing a guitar.
a musician is playing a harmonica
A guitar is not a harmonica, and one can't sing while playing a harmonica,
exists e1 e2 s1 x1 x2 x3 x4.(while(e1,e2) & Theme(e2,x4) & Actor(e2,x1) & v_play(e2) & n_guitar(x4) & rel(e1,x3) & n_sing(x3) & a_musician(s1) & Theme(s1,x3) & into(e1,x2) & n_microphone(x2) & Actor(e1,x1) & v_event(e1) & n_thing(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_harmonica(x2) & n_musician(x1))