Re: = 0?

On 24 May 2006, at 19:46, Andrzej Kozlowski wrote:

>
> On 24 May 2006, at 16:01, Richard Fateman wrote:
> 
>
> I get
>
> Interval[{-1,1}]-Interval[{-1,1}]
>
>
> Interval[{-2,2}]
>
> In[6]:=
> $Version
>
> Out[6]=
> 5.1 for Mac OS X (October 25, 2004)
>
> This is most certainly correct (as, I think, you point out in your
> post). So whatever you have found, is neither a bug or a feature of
> my copy of Mathematica 5.1. Hmm... perhaps they have some "cracked"
> copies of Mathematica at Berkley? ;-)
>
> Andrzej Kozlowski
> Tokyo, Japan

It took me more than 12 hours to understand the point of RJF's post...
I don't think putting the entire contents into the subject  and then
formulating the body so that it seems to be saying the opposite of
what one wants to say, is a good policy (if one is really hoping for
a response, of course. )

Yes, Mathematica does return

In[8]:=
Interval[{a,b}]-Interval[{a,b}]

Out[8]=
0

Obviously that is because Mathematica does implement interval
arithmetic with symbolic end points. If something is not implemented
I don't think it makes sense to call it a bug or a feature.

Andrzej Kozlowski