Hi,

I guess that some elementary number theory texts have this;
I'm not sure. I published a paper in JSL around 1971 (vol. 36)
showing that the first order theory of the set of all subsemigroups
of (N,+) is undecidable. I may have referenced some proof of your
fact in there.

Ralph

--On Friday, October 08, 2004 3:52 PM +0200 Jiri Adamek
<adamek@...> wrote:

>
> Where do I find a proof that every subsemigroup of the additive
> group of all natural numbers is finitely generated?
>
>
> xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> xxxxxxxxxx alternative e-mail address (in case reply key does not
> work): J.Adamek@...
> xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> xxxxxxxxxx
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>



-----------------------------------------------------------------
Mckenzie, Ralph N
Vanderbilt University
Email: ralph.n.mckenzie@...