WORST_CASE(?,O(n^1))
* Step 1: NaturalPI WORST_CASE(?,O(n^1))
    + Considered Problem:
        - Strict TRS:
            f(x1,0()) -> g(x1,0())
            f(y,S(x)) -> f(S(y),x)
            g(0(),x2) -> x2
            g(S(x),y) -> g(x,S(y))
        - Signature:
            {f/2,g/2} / {0/0,S/1}
        - Obligation:
            innermost runtime complexity wrt. defined symbols {f,g} and constructors {0,S}
    + 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:
          none
        
        Following symbols are considered usable:
          {f,g}
        TcT has computed the following interpretation:
          p(0) = 4          
          p(S) = 1 + x1     
          p(f) = 4*x1 + 5*x2
          p(g) = 4*x1 + x2  
        
        Following rules are strictly oriented:
        f(x1,0()) = 20 + 4*x1    
                  > 4 + 4*x1     
                  = g(x1,0())    
        
        f(y,S(x)) = 5 + 5*x + 4*y
                  > 4 + 5*x + 4*y
                  = f(S(y),x)    
        
        g(0(),x2) = 16 + x2      
                  > x2           
                  = x2           
        
        g(S(x),y) = 4 + 4*x + y  
                  > 1 + 4*x + y  
                  = g(x,S(y))    
        
        
        Following rules are (at-least) weakly oriented:
        

WORST_CASE(?,O(n^1))