WORST_CASE(?,O(n^1))
* Step 1: NaturalPI WORST_CASE(?,O(n^1))
    + Considered Problem:
        - Strict TRS:
            f(0(),y,0(),u) -> true()
            f(0(),y,s(z),u) -> false()
            f(s(x),0(),z,u) -> f(x,u,minus(z,s(x)),u)
            f(s(x),s(y),z,u) -> if(le(x,y),f(s(x),minus(y,x),z,u),f(x,u,z,u))
            perfectp(0()) -> false()
            perfectp(s(x)) -> f(x,s(0()),s(x),s(x))
        - Signature:
            {f/4,perfectp/1} / {0/0,false/0,if/3,le/2,minus/2,s/1,true/0}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {f,perfectp} and constructors {0,false,if,le,minus,s,true}
    + Applied Processor:
        NaturalPI {shape = Linear, restrict = NoRestrict, uargs = UArgs, urules = URules, selector = Nothing}
    + Details:
        We apply a polynomial interpretation of kind constructor-based(linear):
        The following argument positions are considered usable:
          uargs(if) = {3}
        
        Following symbols are considered usable:
          {f,perfectp}
        TcT has computed the following interpretation:
                 p(0) = 6            
                 p(f) = 8 + x1 + 2*x4
             p(false) = 10           
                p(if) = x3           
                p(le) = 8 + x1       
             p(minus) = x2           
          p(perfectp) = 13 + 3*x1    
                 p(s) = 1 + x1       
              p(true) = 4            
        
        Following rules are strictly oriented:
          f(0(),y,0(),u) = 14 + 2*u                                     
                         > 4                                            
                         = true()                                       
        
         f(0(),y,s(z),u) = 14 + 2*u                                     
                         > 10                                           
                         = false()                                      
        
         f(s(x),0(),z,u) = 9 + 2*u + x                                  
                         > 8 + 2*u + x                                  
                         = f(x,u,minus(z,s(x)),u)                       
        
        f(s(x),s(y),z,u) = 9 + 2*u + x                                  
                         > 8 + 2*u + x                                  
                         = if(le(x,y),f(s(x),minus(y,x),z,u),f(x,u,z,u))
        
           perfectp(0()) = 31                                           
                         > 10                                           
                         = false()                                      
        
          perfectp(s(x)) = 16 + 3*x                                     
                         > 10 + 3*x                                     
                         = f(x,s(0()),s(x),s(x))                        
        
        
        Following rules are (at-least) weakly oriented:
        

WORST_CASE(?,O(n^1))