A man rides a bucking horse in a rodeo.
A guy is riding in a competition.
The bucking horse in the rodeo isn't necessarily part of a competition.
exists e2 e1 x1 x2 x3.(Theme(e2,x2) & Actor(e2,x1) & v_ride(e2) & in(x2,x3) & n_rodeo(x3) & n_horse(x2) & Actor(e1,x2) & v_buck(e1) & n_man(x1))
exists e1 x1 x2.(in(e1,x2) & n_competition(x2) & Actor(e1,x1) & v_ride(e1) & n_guy(x1))