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problem with cantor diagonal argument


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Posted (edited)

Ann and Bill independently work on examples of Cantor's diagonal argument.

Ann:

111001...

000111...

101100...

110011...

000110...

010110...

transforms diagonal D1 to alternating '01' sequence T1,


010101...
which can't appear in any list per the cda.

Bill:

000110...

010110...

110001...

000111...

101100...

110011...

transforms diagonal D2 to alternating '10' sequence T2,

101010...

which can't appear in any list per the cda.


If D1 and D2 appear in any list, they must be members of the complete list.
T1=D2.

I.e. a missing sequence is only relative to an individual list.

Edited by phyti
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5 minutes ago, phyti said:

which can't appear in any list per the cda

There is no problem, because the cda does not say that a constructed sequence does not appear in any list, but in the given list.

Quote

If s1, s2, ... , sn, ... is any enumeration of elements from T, then an element s of T can be constructed that doesn't correspond to any sn in the enumeration.

Cantor's diagonal argument - Wikipedia

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That's what I said.
"I.e. a missing sequence is only relative to an individual list".

Here is what Cantor said.

"If E1, E2, …, Ev, … is any simply infinite [einfach unendliche] series of elements of the manifold M, then there always exists an element E of M, which cannot be connected with any element Ev."

"From this proposition it follows immediately that the totality of all elements of M cannot be put into the sequence [Reihenform]: E1, E2, …, Ev, … otherwise we would have the contradiction, that a thing [Ding] E0 would be both an element of M, but also not an element of M."

From the example T1 which is missing from Ann's list is included as D2 in Bill' list.
Thus it is not missing from M.
Missing from a subset does not imply missing from the complete set.
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On 5/24/2023 at 12:24 PM, phyti said:

That's what I said.
"I.e. a missing sequence is only relative to an individual list".

Here is what Cantor said.

"If E1, E2, …, Ev, … is any simply infinite [einfach unendliche] series of elements of the manifold M, then there always exists an element E of M, which cannot be connected with any element Ev."

"From this proposition it follows immediately that the totality of all elements of M cannot be put into the sequence [Reihenform]: E1, E2, …, Ev, … otherwise we would have the contradiction, that a thing [Ding] E0 would be both an element of M, but also not an element of M."

 

 

From the example T1 which is missing from Ann's list is included as D2 in Bill' list.
Thus it is not missing from M.
Missing from a subset does not imply missing from the complete set.

CDA is about cardinality (size) of the two sets (countable vs uncountable).  I am not sure exactly what the problem you have with CDA.  

I am thinking about an analogy to your issue to see what happens if we apply your issue on a much smaller scale. 

Assume Bill and Ann want to do the same thing with a set L vs a smaller set S.  They want to know which set is bigger, but they don't want to count the elements.   I will keep this in binary-type numbers vs natural numbers

Let's say L = {000, 111, 110, 011, 100, 001, 010}, and S = {2, 4, 5}.

(Keep in mind that the correlated elements don't have to be same things. K = {5, 7, 1} has three elements and P = {@, U, 9} also has three elements; their cardinalities are the same).

Ann might get T1 = 101 and Bill might get T2 = 110.  The set L can still be larger than the set S even though T1 doesn't equal T2. 

And clearly, we can always find an element of L that can not match to an element of S.

I see no issue here.  Or am I missing your point?

  

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;

"If E1, E2, …, Ev, … is any simply infinite [einfach unendliche] series of elements of the manifold M, then there always exists an element E0 of M, which cannot be connected with any element Ev."

"From this proposition it follows immediately that the totality of all elements of M cannot be put into the sequence [Reihenform]: E1, E2, …, Ev, … otherwise we would have the contradiction, that a thing [Ding] E0 would be both an element of M, but also not an element of M."

Cantor believes there is a hierarchy of infinities, a communication from above which he is obligated to explain to the world.
Cantor is selling his idea of transfinite numbers to anyone who will listen.
In the above quotes he states there are always elements of M which differ from those in any list, thus there cannot be a one to one correspondence with the set of natural numbers N, even though N is inexhaustible.

The Ann and Bob example contradicts his idea, since one will have an infinite list containing the sequence E0 that the other infinite list does not contain.

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43 minutes ago, phyti said:

In the above quotes he states there are always elements of M which differ from those in any list, thus there cannot be a one to one correspondence with the set of natural numbers N, even though N is inexhaustible.

The Ann and Bob example contradicts his idea, since one will have an infinite list containing the sequence E0 that the other infinite list does not contain.

No, there is no contradiction. As per Cantor, for any list there is an element in M which differs from those in that list.

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