A group performs on stage.
A group of people are rehearsing a musical.
A group that performs on stage may not be rehearing a musical.
exists e1 x1 x2.(on(e1,x2) & n_stage(x2) & Actor(e1,x1) & v_perform(e1) & n_group(x1))
exists e1 x1 x2 x3.(Theme(e1,x3) & Actor(e1,x1) & v_rehearse(e1) & n_musical(x3) & of(x1,x2) & n_people(x2) & n_group(x1))