MAYBE
Input TRS:
      1: +(X,0()) -> X
      2: +(X,s(Y)) -> s(+(X,Y))
      3: double(X) -> +(X,X)
      4: f(0(),s(0()),X) -> f(X,double(X),X)
      5: g(X,Y) -> X
      6: g(X,Y) -> Y
Number of strict rules: 6
Direct POLO(bPol) ... failed.
Uncurrying ... failed.
Dependency Pairs:
     #1: #+(X,s(Y)) -> #+(X,Y)
     #2: #double(X) -> #+(X,X)
     #3: #f(0(),s(0()),X) -> #f(X,double(X),X)
     #4: #f(0(),s(0()),X) -> #double(X)
Number of SCCs: 2, DPs: 2
  SCC { #1 }
POLO(Sum)... succeeded.
      s 	w: x1 + 1
      f 	w: 0
      0 	w: 0
      #double	w: 0
      double	w: 0
      #f 	w: 0
      #g 	w: 0
      + 	w: 0
      g 	w: 0
      #+ 	w: x2
    USABLE RULES: { }
    Removed DPs: #1
Number of SCCs: 1, DPs: 1
  SCC { #3 }
POLO(Sum)... POLO(max)... QLPOS... POLO(mSum)... QWPOpS(mSum)... Mat2b... failed.
Finding a loop...  failed.