# [plt-scheme] Natural numbers

 From: hendrik at topoi.pooq.com (hendrik at topoi.pooq.com) Date: Thu Mar 12 09:26:34 EDT 2009 Previous message: [plt-scheme] Natural numbers Next message: [plt-scheme] Natural numbers Messages sorted by: [date] [thread] [subject] [author]

```On Wed, Mar 11, 2009 at 10:25:33PM -0400, Stephen Bloch wrote:
>
> On Mar 11, 2009, at 8:33 PM, Norman Gray wrote:
>
> >In maths, the term "the natural numbers" refers specifically to the
> >set of positive integers (see for example [1]), and not to any set
> >isomorphic to that.  Thus it does not depend on what you or I may
> >or may not find natural, and its meaning is not really a matter for
> >dispute.  Anyone who refers, in any sort of semi-formal context, to
> >"the natural numbers" as meaning anything other than {n in Z : n >
> >0} is being quixotic.
>
> I was brought up with "the natural numbers" meaning {n in Z : n >=
> 0}.  In both my dissertation and my advisor's, and many of the
> published papers in my field, it is quite important that the natural
> numbers include zero.  In fact, I think it's been years if not
> decades since I saw "the natural numbers" used formally in a sense
> that excluded zero.
>
> >I don't believe computer scientists have a get-out-of-jail-free
> >card here.
>
> Ah, maybe that's it: I went through graduate school surrounded by
> logicians and computer scientists. :-)
>
>
> Then again, if you ask my programming students, you'll get about a
> 50/50 split on the question of whether zero is positive....

That would make sense if half of them grew up on old one's complement
machines, which has a separate plus zero and minus zero in their binary
representations.  But that would probably have to be the over-fifty
crowd.  Do you teach senior citicens?

-- hendrik

```

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