New answers tagged large-cardinals
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A weak (?) form of Shelah cardinals
I think any measurable Woodin cardinal is a limit of weakly Shelah cardinals.
To see this, note that, if $\kappa$ is a Woodin cardinal, for any $f : \kappa \to \kappa$, $\kappa$ is a limit of ...
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5
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Reinhardt's ultimate classes
You can find Reinhardt's philosophy of set theory in
"Set existence principles of Shoenfield, Ackermann, and Powell", Fundamenta Mathematica, vol 84, pp 5-34 and
"Remarks on reflection ...
- 5,744
2
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Accepted
How large is the supremum of minimal $V$-heights of all first-order set theories formulated in a particular language of FOST?
Your ordinal $\beta_\mathcal{L}$ is perfectly well-defined: in my opinion it's more easily thought of as $$\sup\{\alpha: \forall \beta<\alpha(V_\beta\not\equiv V_\alpha)\},$$ and this definition ...
- 21.7k
4
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What's the consistency status/strength of this limitation principle?
This principle is inconsistent: consider the formula $\theta(x)$ = "$x^+$ is the smallest infinite cardinal at which $\mathsf{CH}$ fails." The formula $\theta$ cannot hold on more than one ...
- 21.7k
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Are there interesting examples of theorems proved using ‘height’ extensions?
Here is another example.
The maximality principle in forcing is the scheme asserting of every statement $\varphi$ in the language of set theory that if there is forcing extension $V[G]$ of the set-...
- 194k
6
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Are there interesting examples of theorems proved using ‘height’ extensions?
Here is another instance, which appears in my recent paper with Bokai Yao on second-order reflection in the context of KMU with abundant urelements.
Joel David Hamkins and Bokai Yao, Reflection in ...
- 194k
5
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Equivalences of $\mathcal{F}$-Mahloness
The paper "Small Definably-large Cardinals" by Roger Bosch proves that an inaccessible cardinal is $\Sigma_{n+1}$-Mahlo if and only if it is $\Pi_n$-Mahlo except for $n=1$ (I'm referring to ...
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