A person riding a surfboard comes up over a large wave.
A person rides a surfboard during a contest
Riding over a large wave does not imply that it is a contest.
exists e1 e2 s1 s2 x1 x2 x3 x4.(over(e2,x4) & n_wave(x4) & a_large(s2) & Theme(s2,x4) & a_up(s1) & Manner(e2,s1) & Actor(e2,x1) & v_come(e2) & Theme(e1,x3) & Actor(e1,x2) & v_ride(e1) & n_surfboard(x3) & (x1 = x2) & n_person(x1))
exists e1 x1 x2 x3.(during(e1,x3) & n_contest(x3) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_surfboard(x2) & n_person(x1))