TRS:
 {  sum(0()) -> 0(),
   sum(s(x)) -> +(sum(x), s(x)),
   +(x, 0()) -> x,
  +(x, s(y)) -> s(+(x, y))}
 Cdiprover:
  Interpretation class: pizerosimplemixed
  Complexity bound: POLYTIME COMPUTABLE
  s(X3) = + 1*X3 + 1
  +(X2, X1) = + 0*X2^2 + 0*X1^2 + 1*X2 + 0 + 2*X1 + 0*X1*X2
  sum(X0) = + 2*X0^2 + 0 + 1*X0
  0 = + 1
  
  Qed