Three people singing together.
A trio trying out for a show.
People singing are not assumed to be trying out for a show.
exists e1 p1 x1 x2.(a_topic(x1) & exists s1.(Theme(s1,x2) & a_together(s1)) & Topic(e1,p1) & Actor(e1,x2) & v_sing(e1) & (x1 = x2) & n_people(x1) & card_eq_3(x1))
exists e1 x1 x2 x3 x4.(a_topic(x1) & for(e1,x4) & n_show(x4) & Theme(e1,x3) & Actor(e1,x2) & v_try(e1) & n_out(x3) & (x1 = x2) & n_trio(x1))