MAYBE

Problem:
 double(0()) -> 0()
 double(s(x)) -> s(s(double(x)))
 half(0()) -> 0()
 half(s(0())) -> 0()
 half(s(s(x))) -> s(half(x))
 -(x,0()) -> x
 -(s(x),s(y)) -> -(x,y)
 if(0(),y,z) -> y
 if(s(x),y,z) -> z
 half(double(x)) -> x

Proof:
 DP Processor:
  DPs:
   double#(s(x)) -> double#(x)
   half#(s(s(x))) -> half#(x)
   -#(s(x),s(y)) -> -#(x,y)
  TRS:
   double(0()) -> 0()
   double(s(x)) -> s(s(double(x)))
   half(0()) -> 0()
   half(s(0())) -> 0()
   half(s(s(x))) -> s(half(x))
   -(x,0()) -> x
   -(s(x),s(y)) -> -(x,y)
   if(0(),y,z) -> y
   if(s(x),y,z) -> z
   half(double(x)) -> x
  Usable Rule Processor:
   DPs:
    double#(s(x)) -> double#(x)
    half#(s(s(x))) -> half#(x)
    -#(s(x),s(y)) -> -#(x,y)
   TRS:
    
   TDG Processor:
    DPs:
     double#(s(x)) -> double#(x)
     half#(s(s(x))) -> half#(x)
     -#(s(x),s(y)) -> -#(x,y)
    TRS:
     
    graph:
     -#(s(x),s(y)) -> -#(x,y) -> -#(s(x),s(y)) -> -#(x,y)
     half#(s(s(x))) -> half#(x) -> half#(s(s(x))) -> half#(x)
     double#(s(x)) -> double#(x) -> double#(s(x)) -> double#(x)
    Restore Modifier:
     DPs:
      double#(s(x)) -> double#(x)
      half#(s(s(x))) -> half#(x)
      -#(s(x),s(y)) -> -#(x,y)
     TRS:
      double(0()) -> 0()
      double(s(x)) -> s(s(double(x)))
      half(0()) -> 0()
      half(s(0())) -> 0()
      half(s(s(x))) -> s(half(x))
      -(x,0()) -> x
      -(s(x),s(y)) -> -(x,y)
      if(0(),y,z) -> y
      if(s(x),y,z) -> z
      half(double(x)) -> x
     SCC Processor:
      #sccs: 3
      #rules: 3
      #arcs: 3/9
      DPs:
       double#(s(x)) -> double#(x)
      TRS:
       double(0()) -> 0()
       double(s(x)) -> s(s(double(x)))
       half(0()) -> 0()
       half(s(0())) -> 0()
       half(s(s(x))) -> s(half(x))
       -(x,0()) -> x
       -(s(x),s(y)) -> -(x,y)
       if(0(),y,z) -> y
       if(s(x),y,z) -> z
       half(double(x)) -> x
      Open
      
      DPs:
       half#(s(s(x))) -> half#(x)
      TRS:
       double(0()) -> 0()
       double(s(x)) -> s(s(double(x)))
       half(0()) -> 0()
       half(s(0())) -> 0()
       half(s(s(x))) -> s(half(x))
       -(x,0()) -> x
       -(s(x),s(y)) -> -(x,y)
       if(0(),y,z) -> y
       if(s(x),y,z) -> z
       half(double(x)) -> x
      Open
      
      DPs:
       -#(s(x),s(y)) -> -#(x,y)
      TRS:
       double(0()) -> 0()
       double(s(x)) -> s(s(double(x)))
       half(0()) -> 0()
       half(s(0())) -> 0()
       half(s(s(x))) -> s(half(x))
       -(x,0()) -> x
       -(s(x),s(y)) -> -(x,y)
       if(0(),y,z) -> y
       if(s(x),y,z) -> z
       half(double(x)) -> x
      Open