A person is riding a dune buggy up a sandy hill.
A person is outside on a dune buggy.
A person riding a dune buggy up a sandy hill must be outside.
exists e1 s1 x1 x2 x3 x4.(up(e1,x4) & n_hill(x4) & a_sandy(s1) & Theme(s1,x4) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_buggy(x2) & of(x2,x3) & n_dune(x3) & n_person(x1))
exists s1 s2 x1 x2.(on(s1,x2) & n_buggy(x2) & a_dune(s2) & Theme(s2,x2) & Theme(s1,x1) & a_outside(s1) & n_person(x1))