A man in a brown jacket is leading a black shire horse.
The man is a knight of the White Walkers.
The man can't be a knight of the White Walkers if he is leading a black horse.
exists e1 s1 s2 x1 x2 x3 x4.(Theme(e1,x3) & Actor(e1,x1) & v_lead(e1) & n_horse(x3) & of(x3,x4) & n_shire(x4) & a_black(s2) & Theme(s2,x3) & in(x1,x2) & n_jacket(x2) & a_brown(s1) & Theme(s1,x2) & n_man(x1))
exists p1 x1 x3 x4.(ne_org_walkers(x3) & (x3 = x4) & ne_org_white(x4) & n_man(x1) & exists x2.((x1 = x2) & of(x2,x3) & n_knight(x2)))