a group goes on a hike on a rocky surface.
A group goes hiking.
We assume that hiking is on a rocky surface.
exists e1 s1 x1 x2 x3.(on(e1,x3) & n_surface(x3) & a_rocky(s1) & Theme(s1,x3) & on(e1,x2) & n_hike(x2) & Actor(e1,x1) & v_go(e1) & n_group(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_go(e1) & n_hiking(x2) & n_group(x1))