Two men sleep while traveling.
Some men sleep while riding in their cars.
Even though the men are traveling, they are not necessarily riding in their cars.
exists e2 e1 x1.(while(e1,e2) & Actor(e2,x1) & v_travel(e2) & Actor(e1,x1) & v_sleep(e1) & n_man(x1) & card_eq_2(x1))
exists e2 e1 x1 x2.(while(e1,e2) & in(e2,x2) & n_car(x2) & of(x2,x1) & n_thing(x1) & Actor(e2,x1) & v_ride(e2) & Actor(e1,x1) & v_sleep(e1) & n_man(x1))