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On 8/4/2024 11:46 AM, Ross Finlayson wrote:What theory?On 08/04/2024 07:59 AM, Ross Finlayson wrote:>On 08/04/2024 07:52 AM, Ross Finlayson wrote:On 08/04/2024 03:41 AM, FromTheRafters wrote:>>[...][...][...]
It's kind of like when people say
"hey you know the initial ordinal assignment is
what we can say 'are' cardinals",
For each equivalence relation '#' on a class A
there is a family A/# of partitions of A
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[x] and [y] are the partitions holding x and y
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[x] = {u e A: u # x}
[y] = {u e A: u # y}
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Any element of [x] serves equally well as
a representative of the partition holding x
[x] = [y] ⇔ x # y
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We somewhat.arbitrarily assign initial ordinal ξ
to be the One True Representative of
the partition [ξ] of sets A = |ξ|
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The initial ordinal has a certain elegance.
Being ordinals, any ordinal means an initial ordinal.
But for any set A = |ξ|, [A] = [ξ]
and A serves as a representative just as well.
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⎛ The axiom of choice is equivalent to
⎝ each partition [A] holds an ordinal.
>then it's like,>
"with the Continuum Hypothesis being undecide-able and all,
then there are and aren't ordinals between
what would be those cardinals by their cardinals the ordinals",
We have a description of sets, the ZFC axioms.
In some domains satisfying that description,
the continuum hypothesis is true.
In some domains satisfying that description,
the continuum hypothesis is false.
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Therefore,
the ZFC axioms aren't enough to decide
the continuum hypothesis.
>sort of establishing that>
such a definition does and doesn't
keep itself non-contradictory,
No, that is not established.
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A theory describes more than one model.
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Some claims have proofs.
Those claims are true in each model.
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Some claims are true in each model.
Those claims have proofs.
(That is a very nice result, maybe not super.obvious.)
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True.and.false in different models
does not make a theory contradictory.
The theory is silent, not wrong.
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