This man is kayaking in whitewater.
A man in on a river kayaking.
Not every river is whitewater.
exists e1 x1 x2.(n_man(x1) & in(e1,x2) & n_whitewater(x2) & Actor(e1,x1) & v_kayake(e1))
exists x1 x2 x3 x4.(a_topic(x1) & on(x2,x3) & n_kayaking(x3) & of(x3,x4) & n_river(x4) & in(x1,x2) & n_thing(x2) & n_man(x1))