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MathGroup Archive 2005

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Re: To be or not to be...

  • To: mathgroup at smc.vnet.net
  • Subject: [mg62038] Re: [mg62002] To be or not to be...
  • From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
  • Date: Wed, 9 Nov 2005 05:06:01 -0500 (EST)
  • References: <200511090845.DAA17323@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

On 9 Nov 2005, at 17:45, Ingolf Dahl wrote:

>
> To Mathgroup,
>
> Try the following commands in order:
>
> b = Sequence[]
>
> b == Sequence[]
>
> b != Sequence[]
>
> b === Sequence[]
>
> b =!= Sequence[]
>
> The four last lines all evaluate to "True" for me. Quite amazing!
>
> Best regards
>
> Ingolf Dahl
>
> Sweden
>
>

Your examples are actually equivalent to these:

Equal[]


True


Unequal[]


True


SameQ[]


True


UnsameQ[]


True


This does not seem so extremly amazing to me. The fact that Equal and  
Unequal etc, are defined with 0 arguments is clearly due to some  
"internal" needs of the Mathematica programmng language and has  
little to do with what these relations (which are normally considered  
as binary relations) mean elsewhere.

Andrzej Kozlowski


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