Musician sings into a microphone while playing a guitar.
a musician is dancing while singing
Musicians singing into a microphone are not always dancing.
exists e2 e1 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 e2 e1 x1.(while(e1,e2) & Actor(e2,x1) & v_sing(e2) & Actor(e1,x1) & v_dance(e1) & n_musician(x1))