problem with reduce

*To*: mathgroup at smc.vnet.net*Subject*: [mg100347] problem with reduce*From*: olfa <olfa.mraihi at yahoo.fr>*Date*: Mon, 1 Jun 2009 07:11:15 -0400 (EDT)

Hi mathematica community, I have to solve this example In[88]:= Reduce[Exists[{C[1], C[2]}, Element[{C[1], C[2]}, Integers] && C[1] >= 0 && C[2] >= 0 && i == 1 + C[1] && N == 1 + C[1] + C[2] && iP == 1 + C[1] + C[2] && jP == j - C[2]], {iP, jP}, Backsubstitution -> True] During evaluation of In[88]:= Reduce::nsmet: This system cannot be solved with the methods available to \ Reduce. >> I have observed that when I remove Element[{C[1], C[2]}, Integers] && C [1] >= 0 && C[2] >= 0 like that: In[89]:= Reduce[ Exists[{C[1], C[2]}, i == 1 + C[1] && N == 1 + C[1] + C[2] && iP == 1 + C[1] + C[2] && jP == j - C[2]], {iP, jP}, Backsubstitution -> True] it gives me an output which is: Out[89]= iP == N && jP == i + j - N I need to keep the information that Element[{C[1], C[2]}, Integers] && C[1] >= 0 && C[2] >= 0 but reduce tells me that it cannot solve this system. why and how to deal with this problem? thank you.

**Follow-Ups**:**Re: problem with reduce***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>