A man sleeps while listening to his iPod in the back of a vehicle.
A man sleeping on a road trip.
Sleeping while listening to his iPod does not imply being on a road trip.
exists e1 e2 x1 x2 x3 x4.(n_back(x3) & while(e1,e2) & to(e2,x2) & in(x2,x3) & of(x3,x4) & n_vehicle(x4) & n_ipod(x2) & of(x2,x1) & n_male(x1) & Actor(e2,x1) & v_listen(e2) & Actor(e1,x1) & v_sleep(e1) & n_man(x1))
exists e1 x1 x2 x3 x4.(a_topic(x1) & on(e1,x3) & n_trip(x3) & of(x3,x4) & n_road(x4) & Actor(e1,x2) & v_sleep(e1) & (x1 = x2) & n_man(x1))