MAYBE
* Step 1: AddSinks MAYBE
    + Considered Problem:
        Rules:
          0. f1(A,B)   -> f2(-1 + A,B)     [A >= 1]          (?,1)
          1. f2(A,B)   -> f2(-1 + A,1 + B) [A >= 1]          (?,1)
          2. f999(A,B) -> f1(1,-1 + B)     [B >= 1 && A = 0] (1,1)
          3. f1(A,B)   -> f1(1 + A,-1 + B) [B >= 1]          (?,1)
          4. f2(A,B)   -> f1(1 + A,-1 + B) [B >= 1]          (?,1)
        Signature:
          {(f1,2);(f2,2);(f999,2)}
        Flow Graph:
          [0->{1,4},1->{1,4},2->{0,3},3->{0,3},4->{0,3}]
        
    + Applied Processor:
        AddSinks
    + Details:
        ()
* Step 2: Failure MAYBE
  + Considered Problem:
      Rules:
        0. f1(A,B)   -> f2(-1 + A,B)     [A >= 1]          (?,1)
        1. f2(A,B)   -> f2(-1 + A,1 + B) [A >= 1]          (?,1)
        2. f999(A,B) -> f1(1,-1 + B)     [B >= 1 && A = 0] (1,1)
        3. f1(A,B)   -> f1(1 + A,-1 + B) [B >= 1]          (?,1)
        4. f2(A,B)   -> f1(1 + A,-1 + B) [B >= 1]          (?,1)
        5. f1(A,B)   -> exitus616(A,B)   True              (?,1)
        6. f2(A,B)   -> exitus616(A,B)   True              (?,1)
      Signature:
        {(exitus616,2);(f1,2);(f2,2);(f999,2)}
      Flow Graph:
        [0->{1,4,6},1->{1,4,6},2->{0,3,5},3->{0,3,5},4->{0,3,5},5->{},6->{}]
      
  + Applied Processor:
      LooptreeTransformer
  + Details:
      We construct a looptree:
        P: [0,1,2,3,4,5,6]
        |
        `- p:[0,3,4,1] c: []
MAYBE