A child stands on the porch.
Two children are sitting at the window.
A child can't be two children.
exists e1 x1 x2.(n_porch(x2) & on(e1,x2) & Actor(e1,x1) & v_stand(e1) & n_child(x1))
exists e1 x1 x2.(n_window(x2) & at(e1,x2) & Actor(e1,x1) & v_sit(e1) & n_child(x1) & card_eq_2(x1))