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Topic: Problem with Cantor's diagonal argument
Replies: 65   Last Post: Mar 4, 2002 1:36 PM

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Henry

Posts: 5
Registered: 12/13/04
Problem with Cantor's diagonal argument
Posted: Feb 13, 2002 11:29 PM
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While reading Paul Erdos' story in "My brain is open" I found Cantor's
diagonal argument which he used to 'prove' that the decimals between 0
and 1 are uncountable. What's even worse, he used that to say that the
infinity of the decimals is larger than the infinity of the integers
(but that's another matter). What I would like to know is how could he
establish the diagonal argument on a list that I'm not sure can be
created at all. How can someone create a list like:

1 <--> .2332245.....
2 <--> .4898495.....

The basic question here is how can you assign the number 1 to a
number that has an infinite number of digits. In the example above,
what is the number that 1 'points' to? Since you can keep adding an
infinite number of digits after the decimal point how can you say that
1 is pointing to a specific number? A possible list would be something
like:

1 <--> .25
2 <--> .50

Here the number 1 is assigned to the specific number .25, not to an
arbitrary number that has an infinite number of digits after the
decimal point.

Given these questions, how can the proof itself hold true. I don't
see that its initial premise makes logical sense. What's also
confusing is saying that if you can't use the integers to count the
decimals that kind of assumes that you'll run out of integers (you'll
reach the largest integer ever) which makes no sense. Comments
please!!

In an alternate but related topic, I think it is absurd to talk
about an infinite being larger than another. That just does not make
sense at all. Infinity doesn't have an end so:

Inf + Inf = Inf
Inf * Inf = Inf and so on.


Any comments are welcome






Date Subject Author
2/13/02
Read Problem with Cantor's diagonal argument
Henry
2/13/02
Read Re: Problem with Cantor's diagonal argument
Andy Berget
2/14/02
Read Re: Problem with Cantor's diagonal argument
Mike Oliver
2/14/02
Read Re: Problem with Cantor's diagonal argument
Doug Norris
2/14/02
Read Re: Problem with Cantor's diagonal argument
Keith Keller
2/14/02
Read Re: Problem with Cantor's diagonal argument
Dudley Brooks
2/14/02
Read Re: Problem with Cantor's diagonal argument
Mike Oliver
2/14/02
Read Re: Problem with Cantor's diagonal argument
Dudley Brooks
2/14/02
Read Re: Problem with Cantor's diagonal argument
Dave Seaman
2/14/02
Read Re: Problem with Cantor's diagonal argument
Dudley Brooks
2/14/02
Read Re: Problem with Cantor's diagonal argument
Dave Seaman
2/14/02
Read Re: Problem with Cantor's diagonal argument
Dudley Brooks
2/14/02
Read Re: Problem with Cantor's diagonal argument
Bob Kolker
2/14/02
Read Re: Problem with Cantor's diagonal argument
Dave Seaman
2/14/02
Read Re: Problem with Cantor's diagonal argument
Seth Dutter
2/14/02
Read Re: Problem with Cantor's diagonal argument
mareg@mimosa.csv.warwick.ac.uk
2/14/02
Read Re: Problem with Cantor's diagonal argument
Nico Benschop
2/14/02
Read Re: Problem with Cantor's diagonal argument
mareg@mimosa.csv.warwick.ac.uk
2/14/02
Read Re: Problem with Cantor's diagonal argument
Willondon
2/14/02
Read Re: Problem with Cantor's diagonal argument
Henry
2/14/02
Read Re: Problem with Cantor's diagonal argument
magidin@math.berkeley.edu
2/15/02
Read Re: Problem with Cantor's diagonal argument
Doug Magnoli
2/14/02
Read Re: Problem with Cantor's diagonal argument
mareg@mimosa.csv.warwick.ac.uk
2/14/02
Read Re: Problem with Cantor's diagonal argument
Dudley Brooks
2/14/02
Read Re: Problem with Cantor's diagonal argument
Nico Benschop
2/15/02
Read Re: Problem with Cantor's diagonal argument (re finite case)
Nico Benschop
2/15/02
Read cancel <3C6CD566.97EA8F20@chello.nl>
Nico Benschop
2/15/02
Read Re: Problem with Cantor's diagonal argument
Nico Benschop
2/14/02
Read Re: Problem with Cantor's diagonal argument
Dave Seaman
2/14/02
Read Re: Problem with Cantor's diagonal argument
Herman Jurjus
2/14/02
Read Re: Problem with Cantor's diagonal argument
Dave Seaman
2/15/02
Read Re: Problem with Cantor's diagonal argument
Jon and Mary Frances Miller
2/15/02
Read Re: Problem with Cantor's diagonal argument
Torkel Franzen
2/15/02
Read Re: Problem with Cantor's diagonal argument
Virgil
2/15/02
Read Re: Problem with Cantor's diagonal argument
Harlan Messinger
2/15/02
Read Re: Problem with Cantor's diagonal argument
Virgil
2/15/02
Read Re: Problem with Cantor's diagonal argument
Harlan Messinger
2/15/02
Read Re: Problem with Cantor's diagonal argument
Virgil
2/18/02
Read Re: Problem with Cantor's diagonal argument
Harlan Messinger
2/18/02
Read Re: Problem with Cantor's diagonal argument
Virgil
2/19/02
Read Re: Problem with Cantor's diagonal argument
Harlan Messinger
2/19/02
Read Re: Problem with Cantor's diagonal argument
Virgil
2/19/02
Read Re: Problem with Cantor's diagonal argument
Dudley Brooks
3/4/02
Read Re: Problem with Cantor's diagonal argument
Alexey Dejneka
3/4/02
Read Re: Problem with Cantor's diagonal argument
Torkel Franzen
3/4/02
Read Re: Problem with Cantor's diagonal argument
Alan Stern
2/16/02
Read Re: Problem with Cantor's diagonal argument
Chip Eastham
2/20/02
Read Re: Problem with Cantor's diagonal argument
SRK
2/14/02
Read Re: Problem with Cantor's diagonal argument
Dale Hurliman
2/14/02
Read Re: Problem with Cantor's diagonal argument
Randy Poe
2/14/02
Read Re: Problem with Cantor's diagonal argument
Henry
2/14/02
Read Re: Problem with Cantor's diagonal argument
Randy Poe
2/14/02
Read Re: Problem with Cantor's diagonal argument
Wade Ramey
2/14/02
Read Re: Problem with Cantor's diagonal argument
nospam@auerbachatunity.ncsu.edu
2/14/02
Read Re: Problem with Cantor's diagonal argument
Dudley Brooks
2/15/02
Read Re: Problem with Cantor's diagonal argument
Chris Menzel
2/15/02
Read Re: Problem with Cantor's diagonal argument
Dudley Brooks
2/14/02
Read Re: Problem with Cantor's diagonal argument
Phil Carmody
2/14/02
Read Re: Problem with Cantor's diagonal argument
Harlan Messinger
2/14/02
Read Re: Problem with Cantor's diagonal argument
Jim Heckman
2/15/02
Read Re: Problem with Cantor's diagonal argument
Randy Poe
2/15/02
Read Re: Problem with Cantor's diagonal argument
LarryLard
2/18/02
Read Re: Problem with Cantor's diagonal argument
Harlan Messinger
2/14/02
Read Re: Problem with Cantor's diagonal argument
George Greene
2/15/02
Read Re: Problem with Cantor's diagonal argument
Duran Castore
2/18/02
Read Re: Problem with Cantor's diagonal argument
Jonathan Hoyle

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