A football game.
There is no football game.
There is either a football game, or there is not a football game.
exists x1 x2.(a_topic(x1) & n_game(x1) & of(x1,x2) & n_football(x2))
exists p1 x1.-exists x2 x3.((x1 = x2) & n_game(x2) & of(x2,x3) & n_football(x3))