A referee is intervening in a hockey game.
a referee intervenes at a basketball game
referee can intervene in a hockey game or in a basketball game and not both
exists e1 x1 x2 x3.(in(e1,x2) & n_game(x2) & of(x2,x3) & n_hockey(x3) & Actor(e1,x1) & v_intervene(e1) & n_referee(x1))
exists e1 x1 x2 x3.(at(e1,x2) & n_game(x2) & of(x2,x3) & n_basketball(x3) & Actor(e1,x1) & v_intervene(e1) & n_referee(x1))