A man riding a cart pulled by a donkey.
A donkey riding a man while carrying a cart.
A man riding a cart cannot have a donkey riding the man at the same time
exists e1 e2 x1 x2 x3 x4.(Actor(e2,x4) & n_donkey(x4) & Theme(e2,x1) & v_pull(e2) & Theme(e1,x3) & Actor(e1,x2) & v_ride(e1) & n_cart(x3) & (x1 = x2) & n_man(x1))
exists e1 e2 x1 x2 x3 x4.(a_topic(x1) & while(e1,e2) & Theme(e2,x4) & Actor(e2,x2) & v_carry(e2) & n_cart(x4) & Theme(e1,x3) & Actor(e1,x2) & v_ride(e1) & n_man(x3) & (x1 = x2) & n_donkey(x1))