WORST_CASE(?,O(n^1))
* Step 1: NaturalPI 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:
        NaturalPI {shape = StronglyLinear, restrict = NoRestrict, uargs = UArgs, urules = URules, selector = Nothing}
    + Details:
        We apply a polynomial interpretation of kind constructor-based(stronglyLinear):
        The following argument positions are considered usable:
          uargs(u21) = {1},
          uargs(u22) = {1}
        
        Following symbols are considered usable:
          {ackin,u21}
        TcT has computed the following interpretation:
           p(ackin) = 8 + x2 
          p(ackout) = 13 + x1
               p(s) = 8 + x1 
             p(u21) = 3 + x1 
             p(u22) = 4 + x1 
        
        Following rules are strictly oriented:
        ackin(s(X),s(Y)) = 16 + Y              
                         > 11 + Y              
                         = u21(ackin(s(X),Y),X)
        
        u21(ackout(X),Y) = 16 + X              
                         > 12 + X              
                         = u22(ackin(Y,X))     
        
        
        Following rules are (at-least) weakly oriented:
        

WORST_CASE(?,O(n^1))