(VAR x y )
(RULES 
        intlist(nil) -> nil
        int(s(x), 0) -> nil
        int(x, x) -> cons(x, nil)
        intlist(cons(x, y)) -> cons(s(x), intlist(y))
        int(s(x), s(y)) -> intlist(int(x, y))
        int(0, s(y)) -> cons(0, int(s(0), s(y)))
        intlist(cons(x, nil)) -> cons(s(x), nil)
        
)