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Re: (x|y) \[element] Integers in Reduce function

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  • Subject: [mg82583] Re: [mg82552] (x|y) \[element] Integers in Reduce function
  • From: Andrzej Kozlowski <akoz at>
  • Date: Thu, 25 Oct 2007 06:10:09 -0400 (EDT)
  • References: <>

On 24 Oct 2007, at 17:31, Steven Siew wrote:

> Consider the following
> Reduce[x^2 - 2 y^2 == 1 && x>= 0 && y>=0 && (x|y) \[element] Integers,
> {x,y} ]
> What does " (x|y) \[element] Integers "   mean?
> Does it mean:
> (a) x is an Integer  AND  y is an Integer
> (b) x is an Integer  OR  y is an Integer
> Thank you
It means AND. The reason is that x|y is a pattern. So what this is  
saying is that everything that the pattern x|y matches is assumed to  
be an integer. But what sort of things does the pattern x|y match?  
Well, it certianly matches x. And it certainly matches y. And it does  
not match anything else in your formula. So both x and y are assumed  
to be integers.

Andrzej Kozlowski

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