We consider the following Problem:

  Strict Trs:
    {  del(.(x, .(y, z))) -> f(=(x, y), x, y, z)
     , f(true(), x, y, z) -> del(.(y, z))
     , f(false(), x, y, z) -> .(x, del(.(y, z)))
     , =(nil(), nil()) -> true()
     , =(.(x, y), nil()) -> false()
     , =(nil(), .(y, z)) -> false()
     , =(.(x, y), .(u(), v())) -> and(=(x, u()), =(y, v()))}
  StartTerms: basic terms
  Strategy: innermost

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

Proof:
  We consider the following Problem:
  
    Strict Trs:
      {  del(.(x, .(y, z))) -> f(=(x, y), x, y, z)
       , f(true(), x, y, z) -> del(.(y, z))
       , f(false(), x, y, z) -> .(x, del(.(y, z)))
       , =(nil(), nil()) -> true()
       , =(.(x, y), nil()) -> false()
       , =(nil(), .(y, z)) -> false()
       , =(.(x, y), .(u(), v())) -> and(=(x, u()), =(y, v()))}
    StartTerms: basic terms
    Strategy: innermost
  
  Certificate: YES(?,O(n^1))
  
  Proof:
    The weightgap principle applies, where following rules are oriented strictly:
    
    TRS Component: {f(false(), x, y, z) -> .(x, del(.(y, z)))}
    
    Interpretation of nonconstant growth:
    -------------------------------------
      The following argument positions are usable:
        Uargs(del) = {}, Uargs(.) = {2}, Uargs(f) = {1}, Uargs(=) = {},
        Uargs(and) = {}
      We have the following EDA-non-satisfying and IDA(1)-non-satisfying matrix interpretation:
      Interpretation Functions:
       del(x1) = [0 0] x1 + [1]
                 [0 0]      [1]
       .(x1, x2) = [0 0] x1 + [1 2] x2 + [0]
                   [0 0]      [0 0]      [1]
       f(x1, x2, x3, x4) = [1 0] x1 + [0 0] x2 + [0 0] x3 + [0 0] x4 + [1]
                           [0 0]      [0 1]      [0 1]      [0 0]      [1]
       =(x1, x2) = [0 0] x1 + [0 0] x2 + [0]
                   [0 0]      [0 0]      [1]
       true() = [0]
                [0]
       false() = [3]
                 [0]
       nil() = [0]
               [0]
       u() = [0]
             [0]
       v() = [0]
             [0]
       and(x1, x2) = [0 0] x1 + [0 0] x2 + [1]
                     [0 0]      [0 0]      [1]
    
    The strictly oriented rules are moved into the weak component.
    
    We consider the following Problem:
    
      Strict Trs:
        {  del(.(x, .(y, z))) -> f(=(x, y), x, y, z)
         , f(true(), x, y, z) -> del(.(y, z))
         , =(nil(), nil()) -> true()
         , =(.(x, y), nil()) -> false()
         , =(nil(), .(y, z)) -> false()
         , =(.(x, y), .(u(), v())) -> and(=(x, u()), =(y, v()))}
      Weak Trs: {f(false(), x, y, z) -> .(x, del(.(y, z)))}
      StartTerms: basic terms
      Strategy: innermost
    
    Certificate: YES(?,O(n^1))
    
    Proof:
      The weightgap principle applies, where following rules are oriented strictly:
      
      TRS Component: {f(true(), x, y, z) -> del(.(y, z))}
      
      Interpretation of nonconstant growth:
      -------------------------------------
        The following argument positions are usable:
          Uargs(del) = {}, Uargs(.) = {2}, Uargs(f) = {1}, Uargs(=) = {},
          Uargs(and) = {}
        We have the following EDA-non-satisfying and IDA(1)-non-satisfying matrix interpretation:
        Interpretation Functions:
         del(x1) = [0 0] x1 + [1]
                   [0 0]      [1]
         .(x1, x2) = [0 0] x1 + [1 0] x2 + [0]
                     [0 0]      [0 0]      [1]
         f(x1, x2, x3, x4) = [1 0] x1 + [0 0] x2 + [0 0] x3 + [0 0] x4 + [1]
                             [0 0]      [1 1]      [1 1]      [0 0]      [1]
         =(x1, x2) = [0 0] x1 + [0 0] x2 + [0]
                     [0 0]      [0 0]      [1]
         true() = [2]
                  [0]
         false() = [0]
                   [0]
         nil() = [0]
                 [0]
         u() = [0]
               [0]
         v() = [0]
               [0]
         and(x1, x2) = [0 0] x1 + [0 0] x2 + [1]
                       [0 0]      [0 0]      [1]
      
      The strictly oriented rules are moved into the weak component.
      
      We consider the following Problem:
      
        Strict Trs:
          {  del(.(x, .(y, z))) -> f(=(x, y), x, y, z)
           , =(nil(), nil()) -> true()
           , =(.(x, y), nil()) -> false()
           , =(nil(), .(y, z)) -> false()
           , =(.(x, y), .(u(), v())) -> and(=(x, u()), =(y, v()))}
        Weak Trs:
          {  f(true(), x, y, z) -> del(.(y, z))
           , f(false(), x, y, z) -> .(x, del(.(y, z)))}
        StartTerms: basic terms
        Strategy: innermost
      
      Certificate: YES(?,O(n^1))
      
      Proof:
        The weightgap principle applies, where following rules are oriented strictly:
        
        TRS Component:
          {  =(nil(), nil()) -> true()
           , =(.(x, y), nil()) -> false()
           , =(nil(), .(y, z)) -> false()
           , =(.(x, y), .(u(), v())) -> and(=(x, u()), =(y, v()))}
        
        Interpretation of nonconstant growth:
        -------------------------------------
          The following argument positions are usable:
            Uargs(del) = {}, Uargs(.) = {2}, Uargs(f) = {1}, Uargs(=) = {},
            Uargs(and) = {}
          We have the following EDA-non-satisfying and IDA(1)-non-satisfying matrix interpretation:
          Interpretation Functions:
           del(x1) = [0 0] x1 + [1]
                     [0 0]      [1]
           .(x1, x2) = [0 0] x1 + [1 0] x2 + [0]
                       [0 0]      [0 0]      [1]
           f(x1, x2, x3, x4) = [1 0] x1 + [0 0] x2 + [0 0] x3 + [0 0] x4 + [1]
                               [0 0]      [1 0]      [1 0]      [0 0]      [1]
           =(x1, x2) = [0 0] x1 + [0 0] x2 + [2]
                       [0 0]      [0 0]      [1]
           true() = [0]
                    [0]
           false() = [0]
                     [0]
           nil() = [0]
                   [0]
           u() = [0]
                 [0]
           v() = [0]
                 [0]
           and(x1, x2) = [0 0] x1 + [0 0] x2 + [1]
                         [0 0]      [0 0]      [1]
        
        The strictly oriented rules are moved into the weak component.
        
        We consider the following Problem:
        
          Strict Trs: {del(.(x, .(y, z))) -> f(=(x, y), x, y, z)}
          Weak Trs:
            {  =(nil(), nil()) -> true()
             , =(.(x, y), nil()) -> false()
             , =(nil(), .(y, z)) -> false()
             , =(.(x, y), .(u(), v())) -> and(=(x, u()), =(y, v()))
             , f(true(), x, y, z) -> del(.(y, z))
             , f(false(), x, y, z) -> .(x, del(.(y, z)))}
          StartTerms: basic terms
          Strategy: innermost
        
        Certificate: YES(?,O(n^1))
        
        Proof:
          The weightgap principle applies, where following rules are oriented strictly:
          
          TRS Component: {del(.(x, .(y, z))) -> f(=(x, y), x, y, z)}
          
          Interpretation of nonconstant growth:
          -------------------------------------
            The following argument positions are usable:
              Uargs(del) = {}, Uargs(.) = {2}, Uargs(f) = {1}, Uargs(=) = {},
              Uargs(and) = {}
            We have the following EDA-non-satisfying and IDA(1)-non-satisfying matrix interpretation:
            Interpretation Functions:
             del(x1) = [0 2] x1 + [0]
                       [0 1]      [0]
             .(x1, x2) = [0 0] x1 + [1 0] x2 + [0]
                         [0 0]      [0 1]      [1]
             f(x1, x2, x3, x4) = [1 0] x1 + [0 0] x2 + [0 0] x3 + [0 2] x4 + [1]
                                 [0 0]      [0 0]      [0 0]      [0 1]      [2]
             =(x1, x2) = [0 0] x1 + [0 0] x2 + [1]
                         [0 0]      [0 0]      [0]
             true() = [1]
                      [0]
             false() = [1]
                       [0]
             nil() = [0]
                     [0]
             u() = [0]
                   [0]
             v() = [0]
                   [0]
             and(x1, x2) = [0 0] x1 + [0 0] x2 + [1]
                           [0 0]      [0 0]      [0]
          
          The strictly oriented rules are moved into the weak component.
          
          We consider the following Problem:
          
            Weak Trs:
              {  del(.(x, .(y, z))) -> f(=(x, y), x, y, z)
               , =(nil(), nil()) -> true()
               , =(.(x, y), nil()) -> false()
               , =(nil(), .(y, z)) -> false()
               , =(.(x, y), .(u(), v())) -> and(=(x, u()), =(y, v()))
               , f(true(), x, y, z) -> del(.(y, z))
               , f(false(), x, y, z) -> .(x, del(.(y, z)))}
            StartTerms: basic terms
            Strategy: innermost
          
          Certificate: YES(O(1),O(1))
          
          Proof:
            We consider the following Problem:
            
              Weak Trs:
                {  del(.(x, .(y, z))) -> f(=(x, y), x, y, z)
                 , =(nil(), nil()) -> true()
                 , =(.(x, y), nil()) -> false()
                 , =(nil(), .(y, z)) -> false()
                 , =(.(x, y), .(u(), v())) -> and(=(x, u()), =(y, v()))
                 , f(true(), x, y, z) -> del(.(y, z))
                 , f(false(), x, y, z) -> .(x, del(.(y, z)))}
              StartTerms: basic terms
              Strategy: innermost
            
            Certificate: YES(O(1),O(1))
            
            Proof:
              Empty rules are trivially bounded

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