Re: what's wrong with this?!!

*To*: mathgroup at smc.vnet.net*Subject*: [mg114936] Re: what's wrong with this?!!*From*: olfa mraihi <olfa.mraihi at yahoo.fr>*Date*: Thu, 23 Dec 2010 03:54:34 -0500 (EST)

So what's wrong with Reduce in Mathematica 5 to get the output Element[n | iP, Integers] && n<= iP < 1 + n? knowing that Reduce has not been modified in Mathematica 8 so why does it give the correct output which is Element[n | iP, Integers] && iP == n? I 'm using Mathematica 5 and I'm constrained to use it because some of my examples work on Mathematica 5 but not on Mathematica 8. Thank you. --- En date de : Mer 22.12.10, Andrzej Kozlowski <akoz at mimuw.edu.pl> a = =E9crit : De: Andrzej Kozlowski <akoz at mimuw.edu.pl> Objet: Re: [mg114909] what's wrong with this?!! =C0: "olfa" <olfa.mraihi at yahoo.fr> Cc: mathgroup at smc.vnet.net Date: Mercredi 22 d=E9cembre 2010, 9h48 The output I get (with Mathematica 8) is: In[76]:= Reduce[Element[{iP, n}, Integers] && !iP < n && Exists[{iPP}, iPP < n && iP == iPP + 1], {iP}, Backsubstitution -> True] Element[n | iP, Integers] && iP == n Andrzej Kozlowski On 22 Dec 2010, at 08:36, olfa wrote: > Hi mathematica community, > > this is the system to solve: > Reduce[ > Element[{iP, N}, Integers] && > Not[(iP < N)] && > Exists[{iPP}, (iPP < N) && iP == iPP + 1], > {iP}, Backsubstitution -> True] > > the output is: > (N | iP) =E2=88=88 Integers && N =E2=89=A4 iP < 1 + N > > but it should be: > iP==N > > so what's the problem what is missing to get the correct output? > > thank you very much.