YES
* Step 1: TrivialSCCs YES
    + Considered Problem:
        Rules:
          0. f6(A,B,C) -> f4(A,B,1)         [A >= 1]                                                                                        (1,1)
          1. f4(A,B,C) -> f3(1 + -1*A,B,0)  [1 + -1*C >= 0 && -1 + C >= 0 && A >= 1 && C = 1]                                               (?,1)
          2. f3(A,B,C) -> f4(-1 + -1*A,B,1) [-1*C >= 0 && -1*A + -1*C >= 0 && C >= 0 && -1*A + C >= 0 && -1*A >= 0 && 0 >= 1 + A && 0 >= C] (?,1)
          3. f3(A,B,C) -> f7(0,D,C)         [-1*C >= 0 && -1*A + -1*C >= 0 && C >= 0 && -1*A + C >= 0 && -1*A >= 0 && A = 0]                (?,1)
          4. f4(A,B,C) -> f7(0,D,C)         [1 + -1*C >= 0 && -1 + C >= 0 && A = 0]                                                         (?,1)
        Signature:
          {(f3,3);(f4,3);(f6,3);(f7,3)}
        Flow Graph:
          [0->{1,4},1->{2,3},2->{1,4},3->{},4->{}]
        
    + Applied Processor:
        TrivialSCCs
    + Details:
        All trivial SCCs of the transition graph admit timebound 1.
* Step 2: UnsatPaths YES
    + Considered Problem:
        Rules:
          0. f6(A,B,C) -> f4(A,B,1)         [A >= 1]                                                                                        (1,1)
          1. f4(A,B,C) -> f3(1 + -1*A,B,0)  [1 + -1*C >= 0 && -1 + C >= 0 && A >= 1 && C = 1]                                               (?,1)
          2. f3(A,B,C) -> f4(-1 + -1*A,B,1) [-1*C >= 0 && -1*A + -1*C >= 0 && C >= 0 && -1*A + C >= 0 && -1*A >= 0 && 0 >= 1 + A && 0 >= C] (?,1)
          3. f3(A,B,C) -> f7(0,D,C)         [-1*C >= 0 && -1*A + -1*C >= 0 && C >= 0 && -1*A + C >= 0 && -1*A >= 0 && A = 0]                (1,1)
          4. f4(A,B,C) -> f7(0,D,C)         [1 + -1*C >= 0 && -1 + C >= 0 && A = 0]                                                         (1,1)
        Signature:
          {(f3,3);(f4,3);(f6,3);(f7,3)}
        Flow Graph:
          [0->{1,4},1->{2,3},2->{1,4},3->{},4->{}]
        
    + Applied Processor:
        UnsatPaths
    + Details:
        We remove following edges from the transition graph: [(0,4)]
* Step 3: Looptree YES
    + Considered Problem:
        Rules:
          0. f6(A,B,C) -> f4(A,B,1)         [A >= 1]                                                                                        (1,1)
          1. f4(A,B,C) -> f3(1 + -1*A,B,0)  [1 + -1*C >= 0 && -1 + C >= 0 && A >= 1 && C = 1]                                               (?,1)
          2. f3(A,B,C) -> f4(-1 + -1*A,B,1) [-1*C >= 0 && -1*A + -1*C >= 0 && C >= 0 && -1*A + C >= 0 && -1*A >= 0 && 0 >= 1 + A && 0 >= C] (?,1)
          3. f3(A,B,C) -> f7(0,D,C)         [-1*C >= 0 && -1*A + -1*C >= 0 && C >= 0 && -1*A + C >= 0 && -1*A >= 0 && A = 0]                (1,1)
          4. f4(A,B,C) -> f7(0,D,C)         [1 + -1*C >= 0 && -1 + C >= 0 && A = 0]                                                         (1,1)
        Signature:
          {(f3,3);(f4,3);(f6,3);(f7,3)}
        Flow Graph:
          [0->{1},1->{2,3},2->{1,4},3->{},4->{}]
        
    + Applied Processor:
        Looptree
    + Details:
        We construct a looptree:
          P: [0,1,2,3,4]
          |
          `- p:[1,2] c: [2]

YES