A group of people on stage singing in concert.
A group of people on stage square-dancing.
People cannot be singing and square-dancing at the same time.
exists e1 x1 x2 x3 x4 x5.(a_topic(x1) & in(e1,x5) & n_concert(x5) & Actor(e1,x4) & v_sing(e1) & (x1 = x4) & on(x1,x3) & n_stage(x3) & of(x1,x2) & n_people(x2) & n_group(x1))
exists x1 x2 x3 x4.(a_topic(x1) & of(x1,x2) & on(x2,x3) & n_square-dancing(x3) & of(x3,x4) & n_stage(x4) & n_people(x2) & n_group(x1))