Four ballet dancers in black costumes are performing on a stage.
people are performing in front of  a large crowd
There are other means of performing for people besides ballet, and a crowd can watch performances somewhere other than a stage.
exists e1 s1 x1 x2 x3 x4.(on(e1,x4) & n_stage(x4) & Actor(e1,x1) & v_perform(e1) & in(x1,x3) & n_costume(x3) & a_black(s1) & Theme(s1,x3) & n_dancer(x1) & of(x1,x2) & n_ballet(x2) & card_eq_4(x1))
exists e1 s1 x1 x2 x3.(in(e1,x2) & of(x2,x3) & n_crowd(x3) & a_large(s1) & Theme(s1,x3) & n_front(x2) & Actor(e1,x1) & v_perform(e1) & n_people(x1))