YES(?,O(1))
* Step 1: TrivialSCCs WORST_CASE(?,O(1))
    + Considered Problem:
        Rules:
          0. f12(A,B,C,D,E) -> f11(A,B,C,D,E) True     (?,1)
          1. f28(A,B,C,D,E) -> f20(A,1,A,1,A) [A >= 1] (1,1)
        Signature:
          {(f11,5);(f12,5);(f20,5);(f28,5)}
        Flow Graph:
          [0->{},1->{}]
        
    + Applied Processor:
        TrivialSCCs
    + Details:
        All trivial SCCs of the transition graph admit timebound 1.
* Step 2: UnsatRules WORST_CASE(?,O(1))
    + Considered Problem:
        Rules:
          0. f12(A,B,C,D,E) -> f11(A,B,C,D,E) True     (1,1)
          1. f28(A,B,C,D,E) -> f20(A,1,A,1,A) [A >= 1] (1,1)
        Signature:
          {(f11,5);(f12,5);(f20,5);(f28,5)}
        Flow Graph:
          [0->{},1->{}]
        
    + Applied Processor:
        UnsatRules
    + Details:
        The problem is already solved.

YES(?,O(1))