Subject: Diagonal Process
Date: Mon, 13 Jan 1997 13:19:08 +0000
From: Airton

I have read that Georg Cantor used the slash diagonal argument to show that the set of the real numbers is great than that of natural numbers. The argument is applied for real numbers between 0 and 1 and is as follow:

  1. write some real numbers between 0 and 1, one under the other dropping the 0. that appears in the beginning. In this way, one gets a matrix of digits.
  2. take the digits in the diagonal, and add 1 to each digit. In this way, you will find another real number that can not be in the list of real numbers that you have in the matrix, because it will differ from any of those by at least one digit: that of the diagonal.
  3. in this way, you show that any list of real numbers between 0 and 1 is incomplete, so you can not find an one-to-one correspondence between this set and the set of integer, and this should show that the set of real numbers between 0 and 1 is greater than that of natural numbers.

My question is: if I take the digits in any row of the matrix as being an integer written from right to left, and then I would have an one-to-one correspondence between the set of natural numbers and that of real numbers between 0 and 1 (1 should not be included, since would result in the same integer as 0. This would mean that the set of real numbers between 0 and 1 is as big as the set of natural numbers. Where is the error in my argument?

|Reply| |Previous| |Next| |Down| |Exchange index| |Contents| |Store|

Copyright © 1996-2012 Alexander Bogomolny

 40615033

A math books store at a unique math study site. Shopping at the store helps maintain the site. Thank you.
Sites for teachers
Sites for parents
Terms of use
Awards
Interactive Activities

CTK Exchange
CTK Wiki Math
CTK Insights - a blog
Math Help
Games & Puzzles
What Is What
Arithmetic
Algebra
Geometry
Probability
Outline Mathematics
Make an Identity
Book Reviews
Stories for Young
Eye Opener
Analog Gadgets
Inventor's Paradox
Did you know?...
Proofs
Math as Language
Things Impossible
Visual Illusions
My Logo
Math Poll
Cut The Knot!
MSET99 Talk
Old and nice bookstore
Other Math sites
Front Page
Movie shortcuts
Personal info
Privacy Policy

Guest book
News sites

Recommend this site

Sites for parents

Education & Parenting

Search:
Keywords:

Google
Web CTK
Supported by
3wVentures