A person wearing a pink robe is riding a bike.
person in a pink robe is riding a bike in a marathon
Just because a person is a riding a bike doesn't mean he is riding a bike in a marathon.
exists e1 e2 s1 x1 x2 x3 x4.(Theme(e2,x4) & Actor(e2,x1) & v_ride(e2) & n_bike(x4) & Theme(e1,x3) & Actor(e1,x2) & v_wear(e1) & n_robe(x3) & a_pink(s1) & Theme(s1,x3) & (x1 = x2) & n_person(x1))
exists e1 s1 x1 x2 x3 x4.(in(e1,x4) & n_marathon(x4) & Theme(e1,x3) & Actor(e1,x1) & v_ride(e1) & n_bike(x3) & in(x1,x2) & n_robe(x2) & a_pink(s1) & Theme(s1,x2) & n_person(x1))