“…4, and let Var = {z,x,y,…}. Let us first consider the function f (2) : N 2 N. It is easy to check that f (2) (7,3) = 4, f (2) (7,7) = 0, f (2) (7,0) = 7, and f (2) (3,7) = 0. f (1) (7) = f (2) (7,0) = 7. f (0) () = f (2) (0,0) = 0. f (3) (7,3,8) = f (2) (7,3) = 4. f (4) (7,3,8,2) = f (2) (7,3) = 4.…”