A man waterskies.
A man waterskies for a competition.
The man did not have to waterski for competition.
exists x1 x2.(a_topic(x1) & n_watersky(x1) & of(x1,x2) & n_man(x2))
exists x1 x2 x3.(a_topic(x1) & for(x1,x3) & n_competition(x3) & n_watersky(x1) & of(x1,x2) & n_man(x2))