Four people sit at a table.
Four people are sitting.
you must be sitting to be at a table
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.(Actor(e1,x1) & v_sit(e1) & n_people(x1) & card_eq_4(x1))