| 释义 | 
		Umbral CalculusThe study of certain properties of Sylvester  from the word ``umbra'' (meaning ``shadow'' in Latin), and reflects the fact that for many types of identities involvingsequences of polynomials with Powers  , ``shadow'' identities are obtained when the polynomials arechanged to discrete values and the exponent in   is changed to the Pochhammer Symbol  .  
 
 For example, Newton's Forward Difference Formula written in the form
    | (1) |  
  with   looks suspiciously like a finite analog of the Taylor Series expansion
   | (2) |  
  where   is the Differential Operator.  Similarly, the Chu-Vandermonde Identity
   | (3) |  
  with   a Binomial Coefficient, looks suspiciously like an analog of  the Binomial Theorem
   | (4) |  
  (Di Bucchianico and Loeb).See also Binomial Theorem, Chu-Vandermonde Identity, Finite Difference References
 Roman, S. and Rota, G.-C.  ``The Umbral Calculus.''  Adv. Math. 27, 95-188, 1978.Roman, S.  The Umbral Calculus.  New York: Academic Press, 1984. 
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