WORST_CASE(?,O(n^1))

Solution:
---------

  append :: [A(8) x A(14)] -(9)-> A(0)
  cons :: [A(6) x A(6)] -(6)-> A(6)
  cons :: [A(4) x A(4)] -(4)-> A(4)
  cons :: [A(8) x A(8)] -(8)-> A(8)
  cons :: [A(0) x A(0)] -(0)-> A(0)
  false :: [] -(0)-> A(0)
  hd :: [A(4)] -(15)-> A(0)
  ifappend :: [A(0) x A(14) x A(8)] -(8)-> A(0)
  is_empty :: [A(6)] -(8)-> A(0)
  nil :: [] -(0)-> A(6)
  nil :: [] -(0)-> A(8)
  tl :: [A(8)] -(15)-> A(0)
  true :: [] -(0)-> A(0)


Cost Free Signatures:
---------------------

  append :: [A_cf(0) x A_cf(0)] -(0)-> A_cf(0)
  cons :: [A_cf(0) x A_cf(0)] -(0)-> A_cf(0)
  ifappend :: [A_cf(0) x A_cf(0) x A_cf(0)] -(0)-> A_cf(0)
  nil :: [] -(0)-> A_cf(0)


Base Constructors:
------------------
  cons_A :: [A(1) x A(1)] -(1)-> A(1)
  false_A :: [] -(0)-> A(1)
  nil_A :: [] -(0)-> A(1)
  true_A :: [] -(0)-> A(1)