An extreme man snowboarding up side down a mountain.
A woman skies in a bikini.
The subject of the sentence is either a man or a woman. And one cannot be both skiing and snowboarding at the same time.
exists e1 s1 s2 x1 x2 x3 x4.(a_topic(x1) & a_up(s2) & Manner(e1,s2) & Theme(e1,x3) & Actor(e1,x2) & v_snowboard(e1) & down(x3,x4) & n_mountain(x4) & n_side(x3) & (x1 = x2) & n_man(x1) & a_extreme(s1) & Theme(s1,x1))
exists x1 x2 x3.(a_topic(x1) & in(x1,x3) & n_bikini(x3) & n_sky(x1) & of(x1,x2) & n_woman(x2))