Drexel dragonThe Math ForumDonate to the Math Forum


Math Forum
 Ask Dr. Math
 Discussions
 Internet Newsletter
 MathTools
 Problems of the Week
 Teacher2Teacher
 Teacher Exchange
 Workshops

Search All of the Math Forum:
Browse our Internet Mathematics Library

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » sci.math.* » sci.math.independent

Topic: Countably Infinite Sets
Replies: 11   Last Post: Dec 28, 2012 9:08 PM

Advanced Search
Reply to this Topic Reply to this Topic

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
netzweltler

Posts: 278
From: Germany
Registered: 8/6/10
Re: Countably Infinite Sets
Posted: Dec 28, 2012 9:16 AM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

On 28 Dez., 03:49, "Ross A. Finlayson" <ross.finlay...@gmail.com>
wrote:
> On Dec 27, 6:43 pm, netzweltler <reinhard_fisc...@arcor.de> wrote:
>
> > Does the set {{1}, {1,2}, {1,2,3}, ...} contain all natural numbers?
>
> What does "..." mean?

"..." means, there is a bijection to the natural numbers

1 -> {1}
2 -> {1,2}
3 -> {1,2,3}
...

>
> Many would include zero.

I cannot see the difference. I could also have asked:
Does the set {{0}, {0,1}, {0,1,2}, ...} contain all natural numbers?

Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2013. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.