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15
votes
Accepted
A proper class of ordinals without an infinite constructible subset
Stanley, M. C., A cardinal preserving immune partition of the ordinals, Fundam. Math. 148, No. 3, 199-221 (1995). ZBL0843.03028.
An infinite set (or class) of ordinals is said to be immune if it nei …
11
votes
Accepted
Coding the universe into a real over better core models
For measurable cardinals, the answer is yes and is due to Sy Friedman. See Coding Over a Measurable Cardinal.
There is some difficulty to extend the result to the context of Woodin cardinals, see Gen …
6
votes
Accepted
Tree property at weak inaccessibles
In his paper Boolean extensions which efface the Mahlo property William Boos proves the following consistency result:
Theorem. Assume GCH holds and $\kappa$ is weakly compact. Then there exists a card …
5
votes
categorical characterization of large cardinals
In the paper Proof theory and set theory Takeuti has given such a characterization for measurable cardinals, strongly compact cardinals, supercompact cardinals and even large cardinals.
Let me first …
14
votes
Accepted
How badly can the GCH fail globally?
In the Foreman-Woodin model The generalized continuum hypothesis can fail everywhere.
for each infinite cardinal $\kappa, 2^\kappa$ is weakly inaccessible.
This answers your last question. The answer …
3
votes
Accepted
The axiom $I_0$ in the absence of $AC$
It is consistent that $AC$ fails and there exists a non-trivial elementary embedding $j: L(V_{\lambda+1}) \to L(V_{\lambda+1})$ with $crit(j) < \lambda,$
and $\lambda$ has uncountable cofinality. See …
5
votes
"Bootstrapping" an unbounded class of inaccessible cardinals
If $\kappa$ is extendible, then there exists a proper class of inaccessible cardinals (and even more).
10
votes
Accepted
Generic saturation of inner models
The concept is inconsistent.
Consider $\mathbb{P}=Add(\omega, \kappa)_L=Add(\omega, \kappa),$ where $\kappa$ is $(2^{\aleph_0})^+$ of $V$. Forcing with $\mathbb{P}$ over $V$ doesn't collapse cardinal …
10
votes
Accepted
Do we know the consistency strength of the Singular Cardinal Hypothesis failing on an uncoun...
Suppose $\kappa$ is a singular cardinal and there are $cf(\kappa)$-many measurable cardinals $\lambda < \kappa$ with $o(\lambda)=\lambda^{++}$ cofinal in $\kappa.$ Then you can perform a Prikry type i …
4
votes
Accepted
Radin forcing preserving large cardinals
If you start with a strong (or a supercompact cardinal) and if you force with Radin forcing
$\mathbb{R}_u$, for some suitable $u$, then you can preserve the full strength (or supercompactness) of $\ka …
8
votes
What are some good lower bounds on the consistency of the failure of the PCF conjecture?
It follows from the work of Gitik and Mitchell Indiscernible sequences for extenders, and the singular cardinal hypothesis that the hypothesis implies the existence of an inner model with overlapping …
2
votes
Set theoretic forcing, large cardinals and probabilistic methods
Today I saw the following paper in which probabilistic arguments are used in a forcing argument:
Halfway New Cardinal Characteristics.
See the proof of 3.4. The paper is written by Jörg Brendle, Lor …
4
votes
Cops, Robbers and Cardinals: The Infinite Manhunt
Here is an answer to question 2. First note that it suffices to consider the case where $\lambda=\kappa.$
For regular $\kappa,$ you may consider the following graph:
The point is that given less t …
7
votes
Does Easton forcing preserve measurable cardinals?
Suppose $GCH$ holds, $U$ is a normal measure on $\kappa$ and $j: V \to M$ is an ultrapower embedding.
Let $F$ be an Easton function on regular cardinals and $P_F$ be the corresponding Easton forcing …
7
votes
Nonessential use of large cardinals
When dealing with the singular cardinals hypothesis ($SCH$), one may face with many such examples, let me say a few:
$\star_1:$ The consistency of the failure of $SCH$ was proved first by silver usin …