(@WM -- I mistakenly emailed this to your private
account. I intended this discussion to be public.
I'm sorry for any trouble to you,)
On 11/22/2019 3:02 AM, Ganzhinterseher wrote:
> Am Freitag, 22. November 2019 00:14:29 UTC+1
> schrieb Jim Burns:
>> On 11/19/2019 12:10 PM, R. Srinivasan wrote:
>>> Actually Mueckenheim does have a paradox here, and
>>> it can be made clear by looking at the following
>>> version of Zeno's dichotomy paradox.
>>
>> Actually, what Mueckenheim has is not a paradox.
>
> But it requires that the sequence of endsegments
> "can jump from infinite to empty without ever going
> through finite!" [Zelos Malum in "Three facts that
> appear incompatible without dark numbers", sci.math
> (20 Nov 2019)]
A better metaphor for the change is, instead of some
infinite leap, a change in topic. We _were_ talking about
a collection of end segments _with_ a last end segment.
_Now_ we are talking about a collection of end segments
_without_ a last end segment.
> My reply: It appears so because the endsegments producing
> the "jump" remain invisible. All definable natural numbers
> belong to FISONs. Therefore all definable endsegments are
> in (1) and are superfluous in (2).
Your reply introduces "natural numbers" which are not
natural numbers. But only some of the time?
You seem to be "resolving" your inconsistencies by
retconning what you mean by "natural number". That's fine
for comic books, but this is mathematics.
----
The following claims are generally part of what is
claimed about "natural numbers".
If you won't agree to these, you are refusing to talk about
natural numbers. You are instead only talking to yourself,
about whatever you have dreamed up. And whatever problems
you see -- even if they are really problems -- are only
problems with what you have dreamed up.
0 is a natural.
(Or, call it something else. The name doesn't matter.)
For each natural k, there is a unique successor Sk,
which is also a natural, such that
-- Sk is not a successor to any other natural
other than k.
For each natural k, there is a sequence seq[k]
of naturals such that
-- seq[k] has finitely many entries
-- seq[k] begins with 0 and ends with k
-- each entry j (other than k) is immediately followed
in the sequence by Sj
-- Sk is not equal to any entry of seq[k].
For example, for 1000000, there is seq[1000000].
0, 1, 2, ..., 999998, 999999, 1000000
seq[1000000] is finite.
It begins with 0 and ends with 1000000.
0 is immediately followed by 1, 1 by 2, etc.
1000001 is not equal to any entry.
----
I. Each natural k is finitely many steps from 0.
II. There are infinitely many naturals (because there is
a 'new' Sk after each k).
I and II are just a matter of _what we mean_ by "natural".
In particular, there is no place for your dark numbers.
You're vague about what it means to be "definable",
but it seems clear that "k is definable" if and only if
"there is a seq[k] as described". Then, _according to_
_what we mean_ , there are no dark numbers.
>> However, it serves nicely as a warning against trusting
>> too much to intuition.
>
> "Intuition" ike this:
No, I'm referring to your _intuition_ that there is some
problem with (1) and (2). Maybe you've read a couple of the
many _arguments_ that have been posted for you explaining
why that's not a problem?
> ∩{E(1), E(2), ..., E(k)} = E(k) for all k (1)
This is equivalent to
Aj,Ak:(( Ai =< k: j >= i ) <-> ( j >= k))
I think all we need to prove this is transitivity
( j>=k ) -> ( k>=i -> j>=i )
> But
> ∩{E(1), E(2), ...} = {} (2)
This is equivalent to
~Ej,Ak: j >= k
Its proof is just a matter of there not being
a largest natural.
But you can't equivocate on what a _natural_ is.
> where all k appearing in (1) can be omitted.
> What remains if not intuition?
Consider the end segments
{ 1,2,3,4,... }
{ 2,3,4,5,... }
{ 3,4,5,6,... }
{ 4,5,6,7,... }
..
1 is not in all end segments.
2 is not in all end segments.
3 is not in all end segments.
4 is not in all end segments.
..
This is a matter of what we mean by "natural":
There are no natural other than the ones with finite
sequences, such as 0,1,2,...,998,999,1000.
All of those naturals (with finite sequences) are not in
the intersection of all end segments. And all of those
naturals are _all of the naturals_
Therefore, the intersection of all end segments is empty.