Four people sit at a table.
Four people are standing on a table.
You can't be sitting and standing at the same time.
exists e1 x1 x2.(at(e1,x2) & n_table(x2) & Actor(e1,x1) & v_sit(e1) & n_people(x1) & card_eq_4(x1))
exists e1 x1 x2.(on(e1,x2) & n_table(x2) & Actor(e1,x1) & v_stand(e1) & n_people(x1) & card_eq_4(x1))