WORST_CASE(?,O(n^1))
* Step 1: Ara WORST_CASE(?,O(n^1))
    + Considered Problem:
        - Strict TRS:
            ackin(s(X),s(Y)) -> u21(ackin(s(X),Y),X)
            u21(ackout(X),Y) -> u22(ackin(Y,X))
        - Signature:
            {ackin/2,u21/2} / {ackout/1,s/1,u22/1}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {ackin,u21} and constructors {ackout,s,u22}
    + Applied Processor:
        Ara {araHeuristics = Heuristics, minDegree = 1, maxDegree = 2, araTimeout = 3, araRuleShifting = Nothing}
    + Details:
        Signatures used:
        ----------------
          ackin :: ["A"(0) x "A"(2)] -(0)-> "A"(2)
          ackout :: ["A"(2)] -(2)-> "A"(2)
          s :: ["A"(0)] -(0)-> "A"(0)
          s :: ["A"(2)] -(2)-> "A"(2)
          u21 :: ["A"(2) x "A"(0)] -(1)-> "A"(2)
          u22 :: ["A"(2)] -(2)-> "A"(2)
        
        
        Cost-free Signatures used:
        --------------------------
        
        
        
        Base Constructor Signatures used:
        ---------------------------------
          "ackout_A" :: ["A"(0)] -(0)-> "A"(0)
          "s_A" :: ["A"(0)] -(0)-> "A"(0)
          "u22_A" :: ["A"(0)] -(0)-> "A"(0)
        

WORST_CASE(?,O(n^1))