MAYBE
* Step 1: UnsatPaths MAYBE
    + Considered Problem:
        Rules:
          0. f0(A,B,C,D) -> f6(B,B,D,D)           True                                                    (1,1)
          1. f6(A,B,C,D) -> f6(-1 + A,B,-1 + C,D) [-1*C + D >= 0 && -1*A + B >= 0 && 0 >= 1 + A]          (?,1)
          2. f6(A,B,C,D) -> f6(-1 + A,B,-1 + C,D) [-1*C + D >= 0 && -1*A + B >= 0 && A >= 1]              (?,1)
          3. f6(A,B,C,D) -> f14(0,B,C,D)          [-1*C + D >= 0 && -1*A + B >= 0 && D >= 1 + B && A = 0] (?,1)
          4. f6(A,B,C,D) -> f14(0,B,C,D)          [-1*C + D >= 0 && -1*A + B >= 0 && B >= 1 + D && A = 0] (?,1)
          5. f6(A,B,C,D) -> f14(0,B,C,B)          [-1*C + D >= 0 && -1*A + B >= 0 && A = 0 && B = D]      (?,1)
        Signature:
          {(f0,4);(f14,4);(f6,4)}
        Flow Graph:
          [0->{1,2,3,4,5},1->{1,2,3,4,5},2->{1,2,3,4,5},3->{},4->{},5->{}]
        
    + Applied Processor:
        UnsatPaths
    + Details:
        We remove following edges from the transition graph: [(1,2),(1,3),(1,4),(1,5),(2,1)]
* Step 2: TrivialSCCs MAYBE
    + Considered Problem:
        Rules:
          0. f0(A,B,C,D) -> f6(B,B,D,D)           True                                                    (1,1)
          1. f6(A,B,C,D) -> f6(-1 + A,B,-1 + C,D) [-1*C + D >= 0 && -1*A + B >= 0 && 0 >= 1 + A]          (?,1)
          2. f6(A,B,C,D) -> f6(-1 + A,B,-1 + C,D) [-1*C + D >= 0 && -1*A + B >= 0 && A >= 1]              (?,1)
          3. f6(A,B,C,D) -> f14(0,B,C,D)          [-1*C + D >= 0 && -1*A + B >= 0 && D >= 1 + B && A = 0] (?,1)
          4. f6(A,B,C,D) -> f14(0,B,C,D)          [-1*C + D >= 0 && -1*A + B >= 0 && B >= 1 + D && A = 0] (?,1)
          5. f6(A,B,C,D) -> f14(0,B,C,B)          [-1*C + D >= 0 && -1*A + B >= 0 && A = 0 && B = D]      (?,1)
        Signature:
          {(f0,4);(f14,4);(f6,4)}
        Flow Graph:
          [0->{1,2,3,4,5},1->{1},2->{2,3,4,5},3->{},4->{},5->{}]
        
    + Applied Processor:
        TrivialSCCs
    + Details:
        All trivial SCCs of the transition graph admit timebound 1.
* Step 3: PolyRank MAYBE
    + Considered Problem:
        Rules:
          0. f0(A,B,C,D) -> f6(B,B,D,D)           True                                                    (1,1)
          1. f6(A,B,C,D) -> f6(-1 + A,B,-1 + C,D) [-1*C + D >= 0 && -1*A + B >= 0 && 0 >= 1 + A]          (?,1)
          2. f6(A,B,C,D) -> f6(-1 + A,B,-1 + C,D) [-1*C + D >= 0 && -1*A + B >= 0 && A >= 1]              (?,1)
          3. f6(A,B,C,D) -> f14(0,B,C,D)          [-1*C + D >= 0 && -1*A + B >= 0 && D >= 1 + B && A = 0] (1,1)
          4. f6(A,B,C,D) -> f14(0,B,C,D)          [-1*C + D >= 0 && -1*A + B >= 0 && B >= 1 + D && A = 0] (1,1)
          5. f6(A,B,C,D) -> f14(0,B,C,B)          [-1*C + D >= 0 && -1*A + B >= 0 && A = 0 && B = D]      (1,1)
        Signature:
          {(f0,4);(f14,4);(f6,4)}
        Flow Graph:
          [0->{1,2,3,4,5},1->{1},2->{2,3,4,5},3->{},4->{},5->{}]
        
    + Applied Processor:
        PolyRank {useFarkas = True, withSizebounds = [], shape = Linear}
    + Details:
        We apply a polynomial interpretation of shape linear:
           p(f0) = x2
          p(f14) = 0 
           p(f6) = x1
        
        Following rules are strictly oriented:
        [-1*C + D >= 0 && -1*A + B >= 0 && A >= 1] ==>                      
                                       f6(A,B,C,D)   = A                    
                                                     > -1 + A               
                                                     = f6(-1 + A,B,-1 + C,D)
        
        
        Following rules are weakly oriented:
                                                           True ==>                      
                                                    f0(A,B,C,D)   = B                    
                                                                 >= B                    
                                                                  = f6(B,B,D,D)          
        
                 [-1*C + D >= 0 && -1*A + B >= 0 && 0 >= 1 + A] ==>                      
                                                    f6(A,B,C,D)   = A                    
                                                                 >= -1 + A               
                                                                  = f6(-1 + A,B,-1 + C,D)
        
        [-1*C + D >= 0 && -1*A + B >= 0 && D >= 1 + B && A = 0] ==>                      
                                                    f6(A,B,C,D)   = A                    
                                                                 >= 0                    
                                                                  = f14(0,B,C,D)         
        
        [-1*C + D >= 0 && -1*A + B >= 0 && B >= 1 + D && A = 0] ==>                      
                                                    f6(A,B,C,D)   = A                    
                                                                 >= 0                    
                                                                  = f14(0,B,C,D)         
        
             [-1*C + D >= 0 && -1*A + B >= 0 && A = 0 && B = D] ==>                      
                                                    f6(A,B,C,D)   = A                    
                                                                 >= 0                    
                                                                  = f14(0,B,C,B)         
        
        
* Step 4: Failure MAYBE
  + Considered Problem:
      Rules:
        0. f0(A,B,C,D) -> f6(B,B,D,D)           True                                                    (1,1)
        1. f6(A,B,C,D) -> f6(-1 + A,B,-1 + C,D) [-1*C + D >= 0 && -1*A + B >= 0 && 0 >= 1 + A]          (?,1)
        2. f6(A,B,C,D) -> f6(-1 + A,B,-1 + C,D) [-1*C + D >= 0 && -1*A + B >= 0 && A >= 1]              (B,1)
        3. f6(A,B,C,D) -> f14(0,B,C,D)          [-1*C + D >= 0 && -1*A + B >= 0 && D >= 1 + B && A = 0] (1,1)
        4. f6(A,B,C,D) -> f14(0,B,C,D)          [-1*C + D >= 0 && -1*A + B >= 0 && B >= 1 + D && A = 0] (1,1)
        5. f6(A,B,C,D) -> f14(0,B,C,B)          [-1*C + D >= 0 && -1*A + B >= 0 && A = 0 && B = D]      (1,1)
      Signature:
        {(f0,4);(f14,4);(f6,4)}
      Flow Graph:
        [0->{1,2,3,4,5},1->{1},2->{2,3,4,5},3->{},4->{},5->{}]
      
  + Applied Processor:
      Failing "Open problems left."
  + Details:
      Open problems left.
MAYBE