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4
votes
1
answer
238
views
almost huge embeddings and stationary correctness
Suppose $\kappa$ is an almost huge cardinal. Using the characterization of Theorem 24.11 in Kanamori's book, one can show that if $j : V \to M$ is an embedding derived from an almost-huge tower of me …
4
votes
1
answer
378
views
Real-valued measurable cardinals and strong ideals
Is it consistent to have (at the same time) a real-valued measurable cardinal and precipitous ideals on small cardinals such as $\omega_1$? What about saturated ideals on small cardinals?
5
votes
1
answer
246
views
Amalgamation via elementary embeddings
Can there exist three transitive models of ZFC with the same ordinals, $M_0,M_1,N$, such that there are elementary embeddings $j_i : M_i \to N$ for $i<2$, but there is no elementary embedding from $M_ …
13
votes
1
answer
572
views
End-extending cardinals
Let us say a cardinal $\kappa$ end-extending if there is a function $F : V_\kappa^{<\omega} \to V_\kappa$ such that:
(a) If $M \subseteq V_\kappa$ is closed under $F$, then $M \prec V_\kappa$.
(b) If …
9
votes
1
answer
286
views
Countably closed end-extensions of elementary submodels
The following is well-known. If $\kappa$ is measurable, $\theta > \kappa$, and $M \prec V_\theta$ has size $<\kappa$, then there is $N\prec V_\theta$ such that $N \supseteq M$, $M \cap \kappa \not= N …
5
votes
1
answer
219
views
supercompactness measure projections
Suppose $\kappa$ is $\kappa^{+\omega}$-supercompact. If $U$ is a normal measure on $\mathcal P_\kappa(\kappa^{+\omega})$, and $j : V \to M$ is the derived embedding, then it is easy to see that $j[\m …
11
votes
1
answer
607
views
A kind of supercompactness
Is there a notion of supercompactness of a cardinal $\kappa$ that implies the following?
For every sequence $\langle \alpha_i : i < \kappa \rangle \subseteq \kappa$ and every $i_0 < \kappa$, there is …
4
votes
1
answer
414
views
Name for an intermediate notion between huge and 2-huge
I am employing a large cardinal notion that has been used explicitly before, and I am wondering if someone has given it a good succinct name.
A cardinal $\kappa$ is huge if there is an elementary $j : …
7
votes
1
answer
474
views
Character of normal ultrafilters
The character of an ultrafilter $U$, denoted $\chi(U)$, is the minimal size of an $A \subseteq U$ such that $(\forall x \in U ) (\exists y \in A) y \subseteq x$. This cardinal characteristic has been …
5
votes
1
answer
582
views
higher-order reflection
In the first-order context, "reflection" of a formula $\varphi(x)$ below $\kappa$ refers to the the following situation:
There are many ordinals $\alpha<\kappa$ such that for all $a \in V_\alpha$ …
3
votes
2
answers
339
views
Ultrafilter projections and critical points of factor maps
Suppose $j : V \to M$ is $\lambda$-supercompactness embedding derived from an $\kappa$-complete normal ultrafilter $U$ on $P_\kappa(\lambda)$, $\lambda$ regular. Suppose $\eta$ is an ordinal such tha …
15
votes
2
answers
540
views
capturing small sets in small factors
Suppose $\kappa$ is a regular cardinal and $P$ is a $\kappa$-c.c. partial order. I want to know when are small sets added by subforcings of size $<\kappa$. The following seems well-known:
Fact: …
5
votes
1
answer
904
views
regularity of ultrafilters
An ultrafilter $U$ is $(\mu,\kappa)$-regular if there is a sequence $\langle X_\alpha : \alpha < \kappa \rangle \subseteq U$ such that for all $y \in [\kappa]^\mu$, $\bigcap_{\alpha \in y} X_\alpha = …
12
votes
2
answers
851
views
tree properties on $\omega_1$ and $\omega_2$
Are the following mutually consistent (relative to large cardinals)?
(1) There are no $\omega_2$-Aronszajn trees.
(2) There is an $\omega_1$-Kurepa tree.
In the models I know of the tree property a …
15
votes
3
answers
1k
views
Singularizing forcing of "small" cardinality?
Can there be a large cardinal $\kappa$ and a forcing of size $\kappa$ that makes $\kappa$ a singular cardinal? The motivation is that the standard Prikry forcing does not have a dense set of size $\k …