A man plays a keyboard on stage.
A man plays a musical instrument on stage.
The musical instrument the man is playing is a keyboard.
exists e1 x1 x2 x3.(on(e1,x3) & n_stage(x3) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_keyboard(x2) & n_man(x1))
exists e1 s1 x1 x2 x3.(on(e1,x3) & n_stage(x3) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_instrument(x2) & a_musical(s1) & Theme(s1,x2) & n_man(x1))