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Re: please is it possible with mathematica, thank you!

  • To: mathgroup at smc.vnet.net
  • Subject: [mg96725] Re: [mg96715] please is it possible with mathematica, thank you!
  • From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
  • Date: Sun, 22 Feb 2009 03:12:50 -0500 (EST)
  • References: <200902220534.AAA12617@smc.vnet.net>

On 22 Feb 2009, at 06:34, olfa wrote:

> Hi mathematica community!
> I have this input: Not[(y > 0)] and Exists[{x}, (x > 0) && y == x -
> 1]
> I want mathematica to give me y==0 as output.
> Is it possible and if it is what predefined function should I use?In
> this function I want to make this assumption:
> x and y are integers.
> thank you very much.
>


You have to add he condition that y is an integer, otherwise your  
conclusion does not follow. There are various of ways of doing this  
this but one that is very close to what you wrote above is:

Reduce[!y > 0 && Element[y, Integers] && Exists[x, x > 0 && y == x - 1]]

y == 0

Andrzej Kozlowski


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