Two bikers pose for a picture, one of which is wearing a skull mask.
The photographer is a biker.
You can not infer there is a biker.
exists e1 e2 x1 x2 x3 x4 x5 x6.(Theme(e2,x5) & Actor(e2,x4) & v_wear(e2) & n_mask(x5) & of(x5,x6) & n_skull(x6) & of(x4,x3) & n_one(x4) & for(e1,x2) & (x2 = x3) & n_picture(x2) & Actor(e1,x1) & v_pose(e1) & n_biker(x1) & card_eq_2(x1))
exists p1 x1.(n_photographer(x1) & exists x2.((x1 = x2) & n_biker(x2)))