Discrete L'Hospital's rule
  The aim is to formulate a discrete analog of L'Hospital's rule and describe some of its applications. While the usual L'Hospital's rule is very well known, its discrete analog apparently was not in the literature. Since the L'Hospital's rule proved to be very useful in many applications, one may think that its discrete analog will also be useful. ======================== This paper is withdrawn: I have learned that the result is known. 
A.G.Ramm