A man plays guitar and sings into a microphone.
A man is playing an instrument while singing.
A guitar is an instrument, therefore the man is playing an instrument.
exists e1 x1 x2 x3 x4 x5.(into(e1,x5) & n_microphone(x5) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & subset_of(x4,x2) & n_sing(x4) & subset_of(x3,x2) & n_guitar(x3) & n_man(x1))
exists e2 e1 x1 x2.(while(e1,e2) & Actor(e2,x1) & v_sing(e2) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_instrument(x2) & n_man(x1))