Re: Cantor's Diagonal

2007-12-23 Thread Russell Standish
On Fri, Dec 21, 2007 at 01:08:38PM +0100, Günther Greindl wrote: Hi Russell, Russell Standish wrote: In your first case, the number (1,1,1,1...) is not a natural number, since it is infinite. In the second case, (0,0,0,...) is a natural number, but is also on the list (at infinity).

Re: Cantor's Diagonal

2007-12-21 Thread Günther Greindl
Hi, Because zero even repeated an infinity of time is zero and is a natural number. (1,1,1,...) can't be a natural number because it is not finite and a natural number is finite. If it was a natural number, then N would not have a total ordering. Ok agreed: I was caught up in viewing it

Re: Cantor's Diagonal

2007-12-21 Thread Quentin Anciaux
Hi, Le Friday 21 December 2007 13:08:38 Günther Greindl, vous avez écrit : Hi Russell, Russell Standish wrote: In your first case, the number (1,1,1,1...) is not a natural number, since it is infinite. In the second case, (0,0,0,...) is a natural number, but is also on the list (at

Re: Cantor's Diagonal

2007-12-21 Thread Günther Greindl
Hi Russell, Russell Standish wrote: In your first case, the number (1,1,1,1...) is not a natural number, since it is infinite. In the second case, (0,0,0,...) is a natural number, but is also on the list (at infinity). Why is (1,1,1,...) not in the list but (0,0,0,...) in the list at

Re: Cantor's Diagonal

2007-12-20 Thread Bruno Marchal
Le 19-déc.-07, à 21:09, Barry Brent a écrit : Excellent, Bruno, Thanks! Well thanks. I will send a next diagonalization post and some references next week, Best, Bruno http://iridia.ulb.ac.be/~marchal/ --~--~-~--~~~---~--~~ You received this message

Re: Cantor's Diagonal

2007-12-19 Thread Bruno Marchal
Hi Barry, Le 18-déc.-07, à 18:52, Barry Brent a écrit : Bruno-- Ahh, my amateur status is nakedly exposed. I'm going to expose my confusion even further now. That is the courageous attitude of the authentic scientists. I like amateur because they have less prejudices, they have inner

Re: Cantor's Diagonal

2007-12-19 Thread Barry Brent
Excellent, Bruno, Thanks! Barry On Dec 19, 2007, at 7:57 AM, Bruno Marchal wrote: Hi Barry, Le 18-déc.-07, à 18:52, Barry Brent a écrit : Bruno-- Ahh, my amateur status is nakedly exposed. I'm going to expose my confusion even further now. That is the courageous attitude of the

Re: Cantor's Diagonal

2007-12-18 Thread Bruno Marchal
Le 17-déc.-07, à 19:04, meekerdb (Brent Meeker) wrote: Bruno wrote: Exercise: What is wrong with the following argument. (I recall that by definition a function from N to N is defined on all natural numbers). (false) theorem: the set of computable functions from N to N is not

Re: Cantor's Diagonal

2007-12-18 Thread Barry Brent
Bruno-- Ahh, my amateur status is nakedly exposed. I'm going to expose my confusion even further now. Never heard of a universal language. I thought I was familiar with Church's thesis, but apparently no. I thought it was the claim that two or three or four concepts (including recursive

Re: Cantor's Diagonal

2007-12-17 Thread Bruno Marchal
Hi Daniel, I agree with Barry, but apaprently you have still a problem, so I comment your posts. Le 16-déc.-07, à 10:49, Daniel Grubbs a écrit : Hi Folks, I joined this list a while ago but I haven't really kept up.  Anyway, I saw the reference to Cantor's Diagonal and thought perhaps

Re: Cantor's Diagonal

2007-12-16 Thread Barry Brent
Hi. Bruno could do this better, but I like the practice. I guess you're trying to demonstrate that the form of Cantor's argument is invalid, by displaying an example in which it produces an absurd result. Start with a set S you want to show is not enumerable. (ie, there is no one-one

Re: Cantor's Diagonal

2007-12-16 Thread Russell Standish
On Sun, Dec 16, 2007 at 04:49:34AM -0500, Daniel Grubbs wrote: Cantor's argument only works by finding a number that satisfies the criteria for inclusion in the list, yet is nowhere to be found in the list. In your first case, the number (1,1,1,1...) is not a natural number, since it is

Re: Cantor's Diagonal

2007-12-16 Thread Daniel Grubbs
Hi Barry, Let me see if I am clear about Cantor's method. Given a set S, and some enumeration of that set (i.e., a no one-one onto map from Z^+ to S) we can use the diagonalization method to find an D which is a valid element of S but is different from any particular indexed element in the

Re: Cantor's Diagonal

2007-12-16 Thread Barry Brent
Hi Dan, Let me take your statements a few at a time. Let me see if I am clear about Cantor's method. Given a set S, and some enumeration of that set (i.e., a no one-one onto map from Z^+ to S) we can use the diagonalization method to find an D which is a valid element of S but is

Re: Cantor's Diagonal

2007-12-04 Thread Bruno Marchal
Le 03-déc.-07, à 16:56, David Nyman a écrit : On Nov 20, 4:40 pm, Bruno Marchal [EMAIL PROTECTED] wrote: Conclusion: 2^N, the set of infinite binary sequences, is not enumerable. All right? OK. I have to try to catch up now, because I've had to be away longer than I expected, but I'm

Re: Cantor's Diagonal

2007-12-03 Thread David Nyman
On Nov 20, 4:40 pm, Bruno Marchal [EMAIL PROTECTED] wrote: Conclusion: 2^N, the set of infinite binary sequences, is not enumerable. All right? OK. I have to try to catch up now, because I've had to be away longer than I expected, but I'm clear on this diagonal argument. David Hi,

Re: elaboration Re: Cantor's Diagonal

2007-11-22 Thread Bruno Marchal
Le 22-nov.-07, à 07:19, Barry Brent a écrit : The reason it isn't a bijection (of a denumerable set with the set of binary sequences): the pre-image (the left side of your map) isn't a set--you've imposed an ordering. Sets, qua sets, don't have orderings. Orderings are extra. (I'm not

Re: Cantor's Diagonal

2007-11-22 Thread Bruno Marchal
Le 21-nov.-07, à 17:33, Torgny Tholerus a écrit : What do you think of this proof?: Let us have the bijection: 0 {0,0,0,0,0,0,0,...} 1 {1,0,0,0,0,0,0,...} 2 {0,1,0,0,0,0,0,...} 3 {1,1,0,0,0,0,0,...} 4 {0,0,1,0,0,0,0,...} 5

Re: Cantor's Diagonal

2007-11-21 Thread Bruno Marchal
Le 20-nov.-07, à 17:47, David Nyman a écrit : On 20/11/2007, Bruno Marchal [EMAIL PROTECTED] wrote: David, are you still there? This is a key post, with respect to the Church Thesis thread. Sorry Bruno, do forgive me - we seem destined to be out of synch at the moment. I'm afraid I'm

Re: Cantor's Diagonal

2007-11-21 Thread Bruno Marchal
Le 20-nov.-07, à 23:39, Barry Brent wrote : You're saying that, just because you can *write down* the missing sequence (at the beginning, middle or anywhere else in the list), it follows that there *is* no missing sequence. Looks pretty wrong to me. Cantor's proof disqualifies any

Re: Cantor's Diagonal

2007-11-21 Thread Bruno Marchal
Le 21-nov.-07, à 08:49, Torgny Tholerus a écrit : meekerdb skrev:Torgny Tholerus wrote: An ultrafinitist comment to this: == You can add this complementary sequence to the end of the list. That will make you have a list with this complementary sequence included. But then you

Re: Cantor's Diagonal

2007-11-21 Thread Torgny Tholerus
Bruno Marchal skrev: Le 20-nov.-07, 23:39, Barry Brent wrote : You're saying that, just because you can *write down* the missing sequence (at the beginning, middle or anywhere else in the list), it follows that there *is* no missing sequence. Looks pretty wrong to me.

elaboration Re: Cantor's Diagonal

2007-11-21 Thread Barry Brent
The reason it isn't a bijection (of a denumerable set with the set of binary sequences): the pre-image (the left side of your map) isn't a set--you've imposed an ordering. Sets, qua sets, don't have orderings. Orderings are extra. (I'm not a specialist on this stuff but I think

Re: Cantor's Diagonal

2007-11-20 Thread David Nyman
On 20/11/2007, Bruno Marchal [EMAIL PROTECTED] wrote: David, are you still there? This is a key post, with respect to the Church Thesis thread. Sorry Bruno, do forgive me - we seem destined to be out of synch at the moment. I'm afraid I'm too distracted this week to respond adequately - back

Re: Cantor's Diagonal

2007-11-20 Thread Torgny Tholerus
Bruno Marchal skrev: But then the complementary sequence (with the 0 and 1 permuted) is also well defined, in Platonia or in the mind of God(s) 0 1 1 0 1 1 ... But this infinite sequence cannot be in the list, above. The "God" in question has to ackonwledge that. The

Re: Cantor's Diagonal

2007-11-20 Thread meekerdb
Torgny Tholerus wrote: Bruno Marchal skrev: But then the complementary sequence (with the 0 and 1 permuted) is also well defined, in Platonia or in the mind of God(s) *0* *1* *1* *0* *1* *1* ... But *this* infinite sequence cannot be in the list, above. The God in question has to

Re: Cantor's Diagonal

2007-11-20 Thread Torgny Tholerus
meekerdb skrev: Torgny Tholerus wrote: An ultrafinitist comment to this: == You can add this complementary sequence to the end of the list. That will make you have a list with this complementary sequence included. But then you can make a new complementary sequence, that is