Four people are cavorting on the rocks at a river's edge
Four people are outside.
As rocks are outside, it means they are outside.
exists e1 x1 x2 x3 x4.(n_rock(x2) & at(e1,x4) & n_edge(x4) & of(x4,x3) & n_river(x3) & on(e1,x2) & Actor(e1,x1) & v_cavort(e1) & n_people(x1) & card_eq_4(x1))
exists s1 x1.(Theme(s1,x1) & a_outside(s1) & n_people(x1) & card_eq_4(x1))