The bike rider is wearing a silver helmet and red shirt.
A biker riding a bike.
Just because the bike rider is wearing a silver helmet and red shirt doesn't necessarily imply that the biker is riding the bike.
exists e1 s1 x1 x2 x3 x4 x5 x6.(n_rider(x1) & of(x1,x2) & n_bike(x2) & Theme(e1,x3) & Actor(e1,x1) & v_wear(e1) & n_shirt(x6) & a_red(s1) & Theme(s1,x6) & n_helmet(x5) & subset_of(x6,x3) & subset_of(x5,x3) & of(x3,x4) & n_silver(x4))
exists e1 x1 x2 x3.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_ride(e1) & n_bike(x3) & (x1 = x2) & n_biker(x1))