MAYBE

Problem:
 double(0()) -> 0()
 double(s(x)) -> s(s(double(x)))
 +(x,0()) -> x
 +(x,s(y)) -> s(+(x,y))
 +(s(x),y) -> s(+(x,y))
 double(x) -> +(x,x)

Proof:
 DP Processor:
  DPs:
   double#(s(x)) -> double#(x)
   +#(x,s(y)) -> +#(x,y)
   +#(s(x),y) -> +#(x,y)
   double#(x) -> +#(x,x)
  TRS:
   double(0()) -> 0()
   double(s(x)) -> s(s(double(x)))
   +(x,0()) -> x
   +(x,s(y)) -> s(+(x,y))
   +(s(x),y) -> s(+(x,y))
   double(x) -> +(x,x)
  Usable Rule Processor:
   DPs:
    double#(s(x)) -> double#(x)
    +#(x,s(y)) -> +#(x,y)
    +#(s(x),y) -> +#(x,y)
    double#(x) -> +#(x,x)
   TRS:
    f6(x,y) -> x
    f6(x,y) -> y
   TDG Processor:
    DPs:
     double#(s(x)) -> double#(x)
     +#(x,s(y)) -> +#(x,y)
     +#(s(x),y) -> +#(x,y)
     double#(x) -> +#(x,x)
    TRS:
     f6(x,y) -> x
     f6(x,y) -> y
    graph:
     +#(s(x),y) -> +#(x,y) -> +#(s(x),y) -> +#(x,y)
     +#(s(x),y) -> +#(x,y) -> +#(x,s(y)) -> +#(x,y)
     +#(x,s(y)) -> +#(x,y) -> +#(s(x),y) -> +#(x,y)
     +#(x,s(y)) -> +#(x,y) -> +#(x,s(y)) -> +#(x,y)
     double#(s(x)) -> double#(x) -> double#(x) -> +#(x,x)
     double#(s(x)) -> double#(x) -> double#(s(x)) -> double#(x)
     double#(x) -> +#(x,x) -> +#(s(x),y) -> +#(x,y)
     double#(x) -> +#(x,x) -> +#(x,s(y)) -> +#(x,y)
    Restore Modifier:
     DPs:
      double#(s(x)) -> double#(x)
      +#(x,s(y)) -> +#(x,y)
      +#(s(x),y) -> +#(x,y)
      double#(x) -> +#(x,x)
     TRS:
      double(0()) -> 0()
      double(s(x)) -> s(s(double(x)))
      +(x,0()) -> x
      +(x,s(y)) -> s(+(x,y))
      +(s(x),y) -> s(+(x,y))
      double(x) -> +(x,x)
     SCC Processor:
      #sccs: 2
      #rules: 3
      #arcs: 8/16
      DPs:
       double#(s(x)) -> double#(x)
      TRS:
       double(0()) -> 0()
       double(s(x)) -> s(s(double(x)))
       +(x,0()) -> x
       +(x,s(y)) -> s(+(x,y))
       +(s(x),y) -> s(+(x,y))
       double(x) -> +(x,x)
      Open
      
      DPs:
       +#(s(x),y) -> +#(x,y)
       +#(x,s(y)) -> +#(x,y)
      TRS:
       double(0()) -> 0()
       double(s(x)) -> s(s(double(x)))
       +(x,0()) -> x
       +(x,s(y)) -> s(+(x,y))
       +(s(x),y) -> s(+(x,y))
       double(x) -> +(x,x)
      Open