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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 …
Mohammad Golshani's user avatar
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 …
Mohammad Golshani's user avatar
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 …
Mohammad Golshani's user avatar
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 …
Mohammad Golshani's user avatar
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 …
Mohammad Golshani's user avatar
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 …
Mohammad Golshani's user avatar
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).
Mohammad Golshani's user avatar
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 …
Mohammad Golshani's user avatar
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 …
Mohammad Golshani's user avatar
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 …
Mohammad Golshani's user avatar
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 …
Mohammad Golshani's user avatar
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 …
Mohammad Golshani's user avatar
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 …
Mohammad Golshani's user avatar
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 …
Mohammad Golshani's user avatar
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 …
Mohammad Golshani's user avatar

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