Sujet : Re: Incompleteness of Cantor's enumeration of the rational numbers
De : james.g.burns (at) *nospam* att.net (Jim Burns)
Groupes : sci.mathDate : 30. Nov 2024, 22:45:48
Autres entêtes
Organisation : A noiseless patient Spider
Message-ID : <7d09acd3-9778-4271-ac10-2f202d611bc5@att.net>
References : 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
User-Agent : Mozilla Thunderbird
On 11/30/2024 2:07 PM, WM wrote:
On 30.11.2024 18:32, Jim Burns wrote:
Apparently, what you (WM) call "the intersection"
is each of infinitely.many intersections,
>
and their limit.
some infinite, some empty,
"changing" from one to another,
in a manner you accept or you do not accept.
The limit of
all the end segments of the finite cardinals
is one of those intersections.
It is the set of common finite.cardinals,
common to each end.segment, that is, their intersection.
It is empty.
Intersections of some other end.segment.collections
are infinite. And still others also empty.
Our sets do not change.
>
But there is a sequence of endsegments
E(1), E(2), E(3), ...
With an empty set of common finite.cardinals.
and a sequence of their intersections
E(1), E(1)∩E(2), E(1)∩E(2)∩E(3), ... .
With an empty set of common finite.cardinals.
Both are identical -
from the first endsegment
on until every existing endsegment.
Yes, they are identical. And identically empty.
----
Consider a finite.cardinal ξ
There are only finitely.many
fore.segments ⟦0,β⟧ ⊆ ⟦0,ξ-1⟧ which ξ is not.in.
There only finitely.many
end.segments E(β+1) = ℕ\⟦0,β⟧ which ξ is in.
Consider a collection Ends of end.segments.
If Ends is an infinite collection,
then
⎛ there are more end.segments in Ends
⎜ than there are end.segments holding ξ
⎜ ξ is not common to all end.segments in Ends
⎝ ξ is not.in ⋂Ends
The same argument applies to each finite cardinal.
If Ends is an infinite collection,
then
⎛ Each finite.cardinal is not.in ⋂Ends
⎝ ⋂Ends = {}
Each infinite collection of
end.segments of
finite.cardinals
has an empty intersection.