Two kids in a green tree.
Two children on a seesaw.
The two kids cannot be simultaneously in a green tree, and on a seesaw.
exists s1 x1 x2.(a_topic(x1) & in(x1,x2) & n_tree(x2) & a_green(s1) & Theme(s1,x2) & n_kid(x1) & card_eq_2(x1))
exists x1 x2.(a_topic(x1) & on(x1,x2) & n_seesaw(x2) & n_child(x1) & card_eq_2(x1))