a biker performs a trick in the air.
A biker is competing in a tricks competition.
A biker doing tricks is not necessarily competing.
exists e1 x1 x2 x3.(n_air(x3) & in(e1,x3) & Theme(e1,x2) & Actor(e1,x1) & v_perform(e1) & n_trick(x2) & n_biker(x1))
exists e1 x1 x2 x3.(in(e1,x2) & n_competition(x2) & of(x2,x3) & n_trick(x3) & Actor(e1,x1) & v_compete(e1) & n_biker(x1))