We consider the following Problem:

  Strict 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}
  StartTerms: basic terms
  Strategy: innermost

Certificate: YES(?,O(n^1))

Proof:
  We consider the following Problem:
  
    Strict 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}
    StartTerms: basic terms
    Strategy: innermost
  
  Certificate: YES(?,O(n^1))
  
  Proof:
    The weightgap principle applies, where following rules are oriented strictly:
    
    TRS Component:
      {  double(0()) -> 0()
       , half(0()) -> 0()
       , half(s(0())) -> 0()}
    
    Interpretation of nonconstant growth:
    -------------------------------------
      The following argument positions are usable:
        Uargs(double) = {}, Uargs(s) = {1}, Uargs(half) = {},
        Uargs(-) = {}, Uargs(if) = {}
      We have the following EDA-non-satisfying and IDA(1)-non-satisfying matrix interpretation:
      Interpretation Functions:
       double(x1) = [0 0] x1 + [1]
                    [1 0]      [1]
       0() = [0]
             [0]
       s(x1) = [1 0] x1 + [0]
               [0 1]      [0]
       half(x1) = [0 1] x1 + [1]
                  [0 0]      [1]
       -(x1, x2) = [1 0] x1 + [0 0] x2 + [1]
                   [0 0]      [0 0]      [1]
       if(x1, x2, x3) = [1 0] x1 + [1 0] x2 + [0 0] x3 + [1]
                        [0 0]      [0 0]      [0 0]      [1]
    
    The strictly oriented rules are moved into the weak component.
    
    We consider the following Problem:
    
      Strict Trs:
        {  double(s(x)) -> s(s(double(x)))
         , 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}
      Weak Trs:
        {  double(0()) -> 0()
         , half(0()) -> 0()
         , half(s(0())) -> 0()}
      StartTerms: basic terms
      Strategy: innermost
    
    Certificate: YES(?,O(n^1))
    
    Proof:
      The weightgap principle applies, where following rules are oriented strictly:
      
      TRS Component: {if(0(), y, z) -> y}
      
      Interpretation of nonconstant growth:
      -------------------------------------
        The following argument positions are usable:
          Uargs(double) = {}, Uargs(s) = {1}, Uargs(half) = {},
          Uargs(-) = {}, Uargs(if) = {}
        We have the following EDA-non-satisfying and IDA(1)-non-satisfying matrix interpretation:
        Interpretation Functions:
         double(x1) = [0 0] x1 + [1]
                      [1 0]      [1]
         0() = [0]
               [0]
         s(x1) = [1 0] x1 + [0]
                 [0 1]      [0]
         half(x1) = [0 1] x1 + [1]
                    [0 0]      [1]
         -(x1, x2) = [1 0] x1 + [0 0] x2 + [1]
                     [0 0]      [0 0]      [1]
         if(x1, x2, x3) = [1 0] x1 + [1 0] x2 + [0 0] x3 + [1]
                          [0 0]      [0 1]      [0 0]      [1]
      
      The strictly oriented rules are moved into the weak component.
      
      We consider the following Problem:
      
        Strict Trs:
          {  double(s(x)) -> s(s(double(x)))
           , half(s(s(x))) -> s(half(x))
           , -(x, 0()) -> x
           , -(s(x), s(y)) -> -(x, y)
           , if(s(x), y, z) -> z
           , half(double(x)) -> x}
        Weak Trs:
          {  if(0(), y, z) -> y
           , double(0()) -> 0()
           , half(0()) -> 0()
           , half(s(0())) -> 0()}
        StartTerms: basic terms
        Strategy: innermost
      
      Certificate: YES(?,O(n^1))
      
      Proof:
        The weightgap principle applies, where following rules are oriented strictly:
        
        TRS Component: {if(s(x), y, z) -> z}
        
        Interpretation of nonconstant growth:
        -------------------------------------
          The following argument positions are usable:
            Uargs(double) = {}, Uargs(s) = {1}, Uargs(half) = {},
            Uargs(-) = {}, Uargs(if) = {}
          We have the following EDA-non-satisfying and IDA(1)-non-satisfying matrix interpretation:
          Interpretation Functions:
           double(x1) = [0 0] x1 + [1]
                        [1 0]      [1]
           0() = [0]
                 [0]
           s(x1) = [1 0] x1 + [0]
                   [0 1]      [0]
           half(x1) = [0 1] x1 + [1]
                      [0 0]      [1]
           -(x1, x2) = [1 0] x1 + [0 0] x2 + [1]
                       [0 0]      [0 0]      [1]
           if(x1, x2, x3) = [1 0] x1 + [1 0] x2 + [1 0] x3 + [1]
                            [0 0]      [0 1]      [0 1]      [1]
        
        The strictly oriented rules are moved into the weak component.
        
        We consider the following Problem:
        
          Strict Trs:
            {  double(s(x)) -> s(s(double(x)))
             , half(s(s(x))) -> s(half(x))
             , -(x, 0()) -> x
             , -(s(x), s(y)) -> -(x, y)
             , half(double(x)) -> x}
          Weak Trs:
            {  if(s(x), y, z) -> z
             , if(0(), y, z) -> y
             , double(0()) -> 0()
             , half(0()) -> 0()
             , half(s(0())) -> 0()}
          StartTerms: basic terms
          Strategy: innermost
        
        Certificate: YES(?,O(n^1))
        
        Proof:
          The weightgap principle applies, where following rules are oriented strictly:
          
          TRS Component: {-(x, 0()) -> x}
          
          Interpretation of nonconstant growth:
          -------------------------------------
            The following argument positions are usable:
              Uargs(double) = {}, Uargs(s) = {1}, Uargs(half) = {},
              Uargs(-) = {}, Uargs(if) = {}
            We have the following EDA-non-satisfying and IDA(1)-non-satisfying matrix interpretation:
            Interpretation Functions:
             double(x1) = [0 0] x1 + [1]
                          [1 0]      [1]
             0() = [0]
                   [0]
             s(x1) = [1 0] x1 + [0]
                     [0 1]      [0]
             half(x1) = [0 1] x1 + [1]
                        [0 0]      [1]
             -(x1, x2) = [1 0] x1 + [0 0] x2 + [1]
                         [0 1]      [0 0]      [1]
             if(x1, x2, x3) = [0 0] x1 + [1 0] x2 + [1 0] x3 + [1]
                              [0 0]      [0 1]      [0 1]      [1]
          
          The strictly oriented rules are moved into the weak component.
          
          We consider the following Problem:
          
            Strict Trs:
              {  double(s(x)) -> s(s(double(x)))
               , half(s(s(x))) -> s(half(x))
               , -(s(x), s(y)) -> -(x, y)
               , half(double(x)) -> x}
            Weak Trs:
              {  -(x, 0()) -> x
               , if(s(x), y, z) -> z
               , if(0(), y, z) -> y
               , double(0()) -> 0()
               , half(0()) -> 0()
               , half(s(0())) -> 0()}
            StartTerms: basic terms
            Strategy: innermost
          
          Certificate: YES(?,O(n^1))
          
          Proof:
            The weightgap principle applies, where following rules are oriented strictly:
            
            TRS Component:
              {  half(s(s(x))) -> s(half(x))
               , -(s(x), s(y)) -> -(x, y)}
            
            Interpretation of nonconstant growth:
            -------------------------------------
              The following argument positions are usable:
                Uargs(double) = {}, Uargs(s) = {1}, Uargs(half) = {},
                Uargs(-) = {}, Uargs(if) = {}
              We have the following EDA-non-satisfying and IDA(1)-non-satisfying matrix interpretation:
              Interpretation Functions:
               double(x1) = [0 0] x1 + [1]
                            [1 0]      [0]
               0() = [0]
                     [0]
               s(x1) = [1 0] x1 + [2]
                       [0 1]      [0]
               half(x1) = [1 1] x1 + [1]
                          [0 0]      [0]
               -(x1, x2) = [1 0] x1 + [0 0] x2 + [1]
                           [0 1]      [0 0]      [1]
               if(x1, x2, x3) = [0 0] x1 + [1 0] x2 + [1 0] x3 + [1]
                                [0 0]      [0 1]      [0 1]      [1]
            
            The strictly oriented rules are moved into the weak component.
            
            We consider the following Problem:
            
              Strict Trs:
                {  double(s(x)) -> s(s(double(x)))
                 , half(double(x)) -> x}
              Weak Trs:
                {  half(s(s(x))) -> s(half(x))
                 , -(s(x), s(y)) -> -(x, y)
                 , -(x, 0()) -> x
                 , if(s(x), y, z) -> z
                 , if(0(), y, z) -> y
                 , double(0()) -> 0()
                 , half(0()) -> 0()
                 , half(s(0())) -> 0()}
              StartTerms: basic terms
              Strategy: innermost
            
            Certificate: YES(?,O(n^1))
            
            Proof:
              The weightgap principle applies, where following rules are oriented strictly:
              
              TRS Component: {half(double(x)) -> x}
              
              Interpretation of nonconstant growth:
              -------------------------------------
                The following argument positions are usable:
                  Uargs(double) = {}, Uargs(s) = {1}, Uargs(half) = {},
                  Uargs(-) = {}, Uargs(if) = {}
                We have the following EDA-non-satisfying and IDA(1)-non-satisfying matrix interpretation:
                Interpretation Functions:
                 double(x1) = [0 1] x1 + [1]
                              [1 0]      [1]
                 0() = [0]
                       [0]
                 s(x1) = [1 0] x1 + [0]
                         [0 1]      [0]
                 half(x1) = [0 1] x1 + [0]
                            [1 0]      [0]
                 -(x1, x2) = [1 0] x1 + [0 0] x2 + [1]
                             [0 1]      [0 0]      [1]
                 if(x1, x2, x3) = [0 0] x1 + [1 0] x2 + [1 0] x3 + [1]
                                  [0 0]      [0 1]      [0 1]      [1]
              
              The strictly oriented rules are moved into the weak component.
              
              We consider the following Problem:
              
                Strict Trs: {double(s(x)) -> s(s(double(x)))}
                Weak Trs:
                  {  half(double(x)) -> x
                   , half(s(s(x))) -> s(half(x))
                   , -(s(x), s(y)) -> -(x, y)
                   , -(x, 0()) -> x
                   , if(s(x), y, z) -> z
                   , if(0(), y, z) -> y
                   , double(0()) -> 0()
                   , half(0()) -> 0()
                   , half(s(0())) -> 0()}
                StartTerms: basic terms
                Strategy: innermost
              
              Certificate: YES(?,O(n^1))
              
              Proof:
                We consider the following Problem:
                
                  Strict Trs: {double(s(x)) -> s(s(double(x)))}
                  Weak Trs:
                    {  half(double(x)) -> x
                     , half(s(s(x))) -> s(half(x))
                     , -(s(x), s(y)) -> -(x, y)
                     , -(x, 0()) -> x
                     , if(s(x), y, z) -> z
                     , if(0(), y, z) -> y
                     , double(0()) -> 0()
                     , half(0()) -> 0()
                     , half(s(0())) -> 0()}
                  StartTerms: basic terms
                  Strategy: innermost
                
                Certificate: YES(?,O(n^1))
                
                Proof:
                  The problem is match-bounded by 1.
                  The enriched problem is compatible with the following automaton:
                  {  double_0(2) -> 1
                   , double_1(2) -> 4
                   , 0_0() -> 1
                   , 0_0() -> 2
                   , 0_1() -> 4
                   , s_0(1) -> 1
                   , s_0(2) -> 1
                   , s_0(2) -> 2
                   , s_1(3) -> 1
                   , s_1(3) -> 4
                   , s_1(4) -> 3
                   , half_0(2) -> 1
                   , -_0(2, 2) -> 1
                   , if_0(2, 2, 2) -> 1}

Hurray, we answered YES(?,O(n^1))