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MathGroup Archive 2006

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Re: Why does Reduce work this way ...?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg67255] Re: [mg67225] Why does Reduce work this way ...?
  • From: "Chris Chiasson" <chris at chiasson.name>
  • Date: Wed, 14 Jun 2006 06:29:27 -0400 (EDT)
  • References: <200606130507.BAA23801@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

I found Inequality in some output a while ago. I emailed tech support
and Tom Zeller pointed me to the following explanation in section
A.2.7 of the Mathematica Book:

Relational Operators:
Relational operators can be mixed. An expression like a > b >= c is
converted to Inequality[a, Greater, b, GreaterEqual, c], which
effectively evaluates as (a > b) && (b >= c). (The reason for the
intermediate Inequality form is that it prevents objects from being
evaluated twice when input like a > b >= c is processed.)

On 6/13/06, jackgoldberg at comcast.net <jackgoldberg at comcast.net> wrote:
> Hi folks,
>
> This post is related to a previous series of posts about ReplaceAll in a set of inequalities.
> I have "reduced" the problem to this unexpected situation:
>
> In[1]  FullForm[-3<=x<=1]
> Out[1]  LessEqual[-3,x,1]
>
> In[2] Reduce[-3<=x<=1]
> Out[2]  -3<=x<=1
>
> In[3]  FullForm[%2]
> Out[3]  Inequality[-3, LessEqual, y, LessEqual, 1]
>
> In[4] Reduce[ LessEqual[-3,x,1]
> Out[4] -3 &#8804; x &#8804; 1
>
> In[5] FullForm[%4]
> Out[5]  Inequality[-3, LessEqual, y, LessEqual, 1]
>
> This defies my understanding.  What is qoing on with Reduce?
>
> Jack
>
>


-- 
http://chris.chiasson.name/


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