A skier pauses on a mountaintop.
A person is riding a bike on top of a mountain.
either there is a skier or a person riding a bike
exists e1 x1 x2.(on(e1,x2) & n_mountaintop(x2) & Actor(e1,x1) & v_pause(e1) & n_skier(x1))
exists e1 x1 x2 x3 x4.(on(e1,x3) & of(x3,x4) & n_mountain(x4) & n_top(x3) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_bike(x2) & n_person(x1))