The two children swinging together on a swing.
Two children on a seesaw.
Two children can either swing together on a swing, or sit on a seesaw, but not both at the same time.
exists e1 p1 x1 x2 x3.(n_child(x1) & card_eq_2(x1) & a_topic(x1) & on(e1,x3) & n_swing(x3) & exists s1.(Theme(s1,x2) & a_together(s1)) & Topic(e1,p1) & Actor(e1,x2) & v_swing(e1) & (x1 = x2))
exists x1 x2.(a_topic(x1) & on(x1,x2) & n_seesaw(x2) & n_child(x1) & card_eq_2(x1))