A man on a motorcycle in the woods wearing a black helmet.
The biker was wearing a helmet.
Just because a man is on a motorcycle does not mean he is a biker.
exists e1 s1 x1 x2 x3 x4 x5.(n_wood(x3) & a_topic(x1) & on(x1,x2) & in(x2,x3) & Theme(e1,x5) & Actor(e1,x4) & v_wear(e1) & n_helmet(x5) & a_black(s1) & Theme(s1,x5) & (x3 = x4) & n_motorcycle(x2) & n_man(x1))
exists e1 x1 x2.(n_biker(x1) & Theme(e1,x2) & Actor(e1,x1) & v_wear(e1) & n_helmet(x2))