There is a man in a blue shirt riding a white horse and jumping a hurdle.
A man competes with a horse.
Just because the man is riding a horse doesn't mean he competes with it.
exists p1 x1 e2 e1 s1 s2 x2 x3 x4 x5 x6 x7.((x1 = x2) & Theme(e2,x7) & Actor(e2,x6) & v_jump(e2) & n_hurdle(x7) & (x2 = x6) & Theme(e1,x5) & Actor(e1,x4) & v_ride(e1) & n_horse(x5) & a_white(s2) & Theme(s2,x5) & (x2 = x4) & in(x2,x3) & n_shirt(x3) & a_blue(s1) & Theme(s1,x3) & n_man(x2))
exists e1 x1 x2.(with(e1,x2) & n_horse(x2) & Actor(e1,x1) & v_compete(e1) & n_man(x1))