We consider the following Problem:

  Strict Trs:
    {  sqr(0()) -> 0()
     , sqr(s(x)) -> +(sqr(x), s(double(x)))
     , double(0()) -> 0()
     , double(s(x)) -> s(s(double(x)))
     , +(x, 0()) -> x
     , +(x, s(y)) -> s(+(x, y))
     , sqr(s(x)) -> s(+(sqr(x), double(x)))}
  StartTerms: basic terms
  Strategy: innermost

Certificate: YES(?,O(n^2))

Proof:
  We consider the following Problem:
  
    Strict Trs:
      {  sqr(0()) -> 0()
       , sqr(s(x)) -> +(sqr(x), s(double(x)))
       , double(0()) -> 0()
       , double(s(x)) -> s(s(double(x)))
       , +(x, 0()) -> x
       , +(x, s(y)) -> s(+(x, y))
       , sqr(s(x)) -> s(+(sqr(x), double(x)))}
    StartTerms: basic terms
    Strategy: innermost
  
  Certificate: YES(?,O(n^2))
  
  Proof:
    The weightgap principle applies, where following rules are oriented strictly:
    
    TRS Component: {sqr(0()) -> 0()}
    
    Interpretation of nonconstant growth:
    -------------------------------------
      The following argument positions are usable:
        Uargs(sqr) = {}, Uargs(s) = {1}, Uargs(+) = {1, 2},
        Uargs(double) = {}
      We have the following EDA-non-satisfying and IDA(1)-non-satisfying matrix interpretation:
      Interpretation Functions:
       sqr(x1) = [0 0] x1 + [1]
                 [1 0]      [1]
       0() = [0]
             [0]
       s(x1) = [1 0] x1 + [0]
               [0 0]      [1]
       +(x1, x2) = [1 0] x1 + [1 0] x2 + [0]
                   [0 0]      [0 0]      [1]
       double(x1) = [0 0] x1 + [0]
                    [0 0]      [1]
    
    The strictly oriented rules are moved into the weak component.
    
    We consider the following Problem:
    
      Strict Trs:
        {  sqr(s(x)) -> +(sqr(x), s(double(x)))
         , double(0()) -> 0()
         , double(s(x)) -> s(s(double(x)))
         , +(x, 0()) -> x
         , +(x, s(y)) -> s(+(x, y))
         , sqr(s(x)) -> s(+(sqr(x), double(x)))}
      Weak Trs: {sqr(0()) -> 0()}
      StartTerms: basic terms
      Strategy: innermost
    
    Certificate: YES(?,O(n^2))
    
    Proof:
      The weightgap principle applies, where following rules are oriented strictly:
      
      TRS Component: {double(0()) -> 0()}
      
      Interpretation of nonconstant growth:
      -------------------------------------
        The following argument positions are usable:
          Uargs(sqr) = {}, Uargs(s) = {1}, Uargs(+) = {1, 2},
          Uargs(double) = {}
        We have the following EDA-non-satisfying and IDA(1)-non-satisfying matrix interpretation:
        Interpretation Functions:
         sqr(x1) = [0 0] x1 + [1]
                   [1 0]      [1]
         0() = [0]
               [0]
         s(x1) = [1 0] x1 + [0]
                 [0 0]      [1]
         +(x1, x2) = [1 0] x1 + [1 0] x2 + [0]
                     [1 0]      [0 0]      [0]
         double(x1) = [0 0] x1 + [2]
                      [0 0]      [1]
      
      The strictly oriented rules are moved into the weak component.
      
      We consider the following Problem:
      
        Strict Trs:
          {  sqr(s(x)) -> +(sqr(x), s(double(x)))
           , double(s(x)) -> s(s(double(x)))
           , +(x, 0()) -> x
           , +(x, s(y)) -> s(+(x, y))
           , sqr(s(x)) -> s(+(sqr(x), double(x)))}
        Weak Trs:
          {  double(0()) -> 0()
           , sqr(0()) -> 0()}
        StartTerms: basic terms
        Strategy: innermost
      
      Certificate: YES(?,O(n^2))
      
      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(sqr) = {}, Uargs(s) = {1}, Uargs(+) = {1, 2},
            Uargs(double) = {}
          We have the following EDA-non-satisfying and IDA(1)-non-satisfying matrix interpretation:
          Interpretation Functions:
           sqr(x1) = [0 0] x1 + [1]
                     [0 0]      [1]
           0() = [1]
                 [0]
           s(x1) = [1 0] x1 + [0]
                   [0 0]      [1]
           +(x1, x2) = [1 0] x1 + [1 0] x2 + [0]
                       [0 1]      [0 0]      [1]
           double(x1) = [0 0] x1 + [2]
                        [0 0]      [1]
        
        The strictly oriented rules are moved into the weak component.
        
        We consider the following Problem:
        
          Strict Trs:
            {  sqr(s(x)) -> +(sqr(x), s(double(x)))
             , double(s(x)) -> s(s(double(x)))
             , +(x, s(y)) -> s(+(x, y))
             , sqr(s(x)) -> s(+(sqr(x), double(x)))}
          Weak Trs:
            {  +(x, 0()) -> x
             , double(0()) -> 0()
             , sqr(0()) -> 0()}
          StartTerms: basic terms
          Strategy: innermost
        
        Certificate: YES(?,O(n^2))
        
        Proof:
          The weightgap principle applies, where following rules are oriented strictly:
          
          TRS Component: {sqr(s(x)) -> +(sqr(x), s(double(x)))}
          
          Interpretation of nonconstant growth:
          -------------------------------------
            The following argument positions are usable:
              Uargs(sqr) = {}, Uargs(s) = {1}, Uargs(+) = {1, 2},
              Uargs(double) = {}
            We have the following EDA-non-satisfying and IDA(1)-non-satisfying matrix interpretation:
            Interpretation Functions:
             sqr(x1) = [1 1] x1 + [0]
                       [0 0]      [1]
             0() = [0]
                   [0]
             s(x1) = [1 0] x1 + [0]
                     [0 1]      [1]
             +(x1, x2) = [1 0] x1 + [1 0] x2 + [0]
                         [0 1]      [0 0]      [0]
             double(x1) = [0 0] x1 + [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)))
               , +(x, s(y)) -> s(+(x, y))
               , sqr(s(x)) -> s(+(sqr(x), double(x)))}
            Weak Trs:
              {  sqr(s(x)) -> +(sqr(x), s(double(x)))
               , +(x, 0()) -> x
               , double(0()) -> 0()
               , sqr(0()) -> 0()}
            StartTerms: basic terms
            Strategy: innermost
          
          Certificate: YES(?,O(n^2))
          
          Proof:
            The weightgap principle applies, where following rules are oriented strictly:
            
            TRS Component: {sqr(s(x)) -> s(+(sqr(x), double(x)))}
            
            Interpretation of nonconstant growth:
            -------------------------------------
              The following argument positions are usable:
                Uargs(sqr) = {}, Uargs(s) = {1}, Uargs(+) = {1, 2},
                Uargs(double) = {}
              We have the following EDA-non-satisfying and IDA(1)-non-satisfying matrix interpretation:
              Interpretation Functions:
               sqr(x1) = [0 1] x1 + [2]
                         [0 1]      [0]
               0() = [0]
                     [0]
               s(x1) = [1 0] x1 + [1]
                       [0 1]      [3]
               +(x1, x2) = [1 0] x1 + [1 0] x2 + [1]
                           [0 1]      [0 0]      [0]
               double(x1) = [0 0] x1 + [0]
                            [0 0]      [0]
            
            The strictly oriented rules are moved into the weak component.
            
            We consider the following Problem:
            
              Strict Trs:
                {  double(s(x)) -> s(s(double(x)))
                 , +(x, s(y)) -> s(+(x, y))}
              Weak Trs:
                {  sqr(s(x)) -> s(+(sqr(x), double(x)))
                 , sqr(s(x)) -> +(sqr(x), s(double(x)))
                 , +(x, 0()) -> x
                 , double(0()) -> 0()
                 , sqr(0()) -> 0()}
              StartTerms: basic terms
              Strategy: innermost
            
            Certificate: YES(?,O(n^2))
            
            Proof:
              We consider the following Problem:
              
                Strict Trs:
                  {  double(s(x)) -> s(s(double(x)))
                   , +(x, s(y)) -> s(+(x, y))}
                Weak Trs:
                  {  sqr(s(x)) -> s(+(sqr(x), double(x)))
                   , sqr(s(x)) -> +(sqr(x), s(double(x)))
                   , +(x, 0()) -> x
                   , double(0()) -> 0()
                   , sqr(0()) -> 0()}
                StartTerms: basic terms
                Strategy: innermost
              
              Certificate: YES(?,O(n^2))
              
              Proof:
                The following argument positions are usable:
                  Uargs(sqr) = {}, Uargs(s) = {1}, Uargs(+) = {1, 2},
                  Uargs(double) = {}
                We have the following restricted  polynomial interpretation:
                Interpretation Functions:
                 [sqr](x1) = x1 + 3*x1^2
                 [0]() = 2
                 [s](x1) = 1 + x1
                 [+](x1, x2) = x1 + 2*x2
                 [double](x1) = 1 + 3*x1

Hurray, we answered YES(?,O(n^2))