WORST_CASE(?,O(n^1))
* Step 1: NaturalPI WORST_CASE(?,O(n^1))
    + Considered Problem:
        - Strict TRS:
            add(0(),X) -> X
            add(s(),Y) -> s()
            from(X) -> cons(X)
            fst(0(),Z) -> nil()
            fst(s(),cons(Y)) -> cons(Y)
            len(cons(X)) -> s()
            len(nil()) -> 0()
        - Signature:
            {add/2,from/1,fst/2,len/1} / {0/0,cons/1,nil/0,s/0}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {add,from,fst,len} and constructors {0,cons,nil,s}
    + 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:
          none
        
        Following symbols are considered usable:
          {add,from,fst,len}
        TcT has computed the following interpretation:
             p(0) = 4          
           p(add) = 2 + x1 + x2
          p(cons) = 1          
          p(from) = 9          
           p(fst) = 8 + x1 + x2
           p(len) = 1 + x1     
           p(nil) = 10         
             p(s) = 0          
        
        Following rules are strictly oriented:
              add(0(),X) = 6 + X  
                         > X      
                         = X      
        
              add(s(),Y) = 2 + Y  
                         > 0      
                         = s()    
        
                 from(X) = 9      
                         > 1      
                         = cons(X)
        
              fst(0(),Z) = 12 + Z 
                         > 10     
                         = nil()  
        
        fst(s(),cons(Y)) = 9      
                         > 1      
                         = cons(Y)
        
            len(cons(X)) = 2      
                         > 0      
                         = s()    
        
              len(nil()) = 11     
                         > 4      
                         = 0()    
        
        
        Following rules are (at-least) weakly oriented:
        

WORST_CASE(?,O(n^1))