Two sprinters are jumping over an obstacle.
Two people jump over a dog.
Two sprinters are jumping over an obstacle but jump not over a dog.
exists e1 x1 x2.(over(e1,x2) & n_obstacle(x2) & Actor(e1,x1) & v_jump(e1) & n_sprinter(x1) & card_eq_2(x1))
exists e1 x1 x2.(over(e1,x2) & n_dog(x2) & Actor(e1,x1) & v_jump(e1) & n_people(x1) & card_eq_2(x1))