In article <hOLgk.14342$9S6.835@[EMAIL PROTECTED]
>, Jack <jj@[EMAIL PROTECTED]
>
wrote:
> "Brian M. Scott" <b.scott@[EMAIL PROTECTED]
> wrote in message
> news:1usfqoaxp7374.gz6czvua09cx.dlg@[EMAIL PROTECTED]
> > On Sat, 19 Jul 2008 22:58:04 +0100, Jack <jj@[EMAIL PROTECTED]
>
> > wrote in <news:trtgk.39540$7B3.5025@[EMAIL PROTECTED]
> in
> > alt.algebra.help:
> >
> > [...]
> >
> >> The thing that perplexes me a little is that Paul was
> >> saying I could define |N as the set of positive integers
> >> if I so wished, which might in retrospect turn out to
> >> be a good option for me; but then if we have t: |N --> |N
> >> you allow me to have t(n)=0, but 0 is not positive.
> >
> > I don't see how this relates to what preceded it.
>
> It's just something that niggles me: if you have a function t: N ---> N
and
> N is by definition a positive integer, it looks wrong to refer to
t(n)=0;
> yet neither you nor Paul objected to the use of N --->N when N could, so
it
> seemed, be the set of positive integers. So if I then say t: Z^+ --->
Z^+,
> and refer to t(n)=0, is that sound or unsound?
>
> Cheers.
>
>
Don't drag me into it. At least twice recently I have explicitly said
|N is the non--negative integers. Once, I even listed it out.
--
Paul Sperry
Columbia, SC (USA)
|
