4
$\begingroup$

Can a Vopenka cardinal be supercompact?

I asked a weaker question on here before. Unfortunately, I don't know enough set theory to see whether the positive answer there generalizes to a positive answer here.

$\endgroup$
2
  • 2
    $\begingroup$ If $\kappa$ is almost huge with target $\lambda,$ then $V_{\lambda}$ thinks that $\kappa$ is a supercompact Vopenka cardinal. See neugierde.github.io/cantors-attic/Huge $\endgroup$ Commented Oct 25, 2021 at 1:03
  • $\begingroup$ @ElliotGlazer Thanks! Looking at the Cantor's attic page, I'm unable to extract the conclusion you've stated -- if you were to say a few words about how you get there, I think that would make a very satisfactory answer to my question. $\endgroup$ Commented Oct 25, 2021 at 3:11

1 Answer 1

9
$\begingroup$

If $\kappa$ is almost huge with target $\lambda,$ then $V_{\lambda}$ thinks that $\kappa$ is a supercompact Vopenka cardinal.

I'll take for granted the standard facts about almost huge cardinals listed here: https://neugierde.github.io/cantors-attic/Huge

In particular, $\kappa$ is Vopenka (in $V$), and this is just an assertion about $V_{\kappa+1}$ so $V_{\lambda}$ also sees that $\kappa$ is Vopenka. Also $\kappa$ is $\theta$-supercompact for every $\theta<\lambda,$ i.e. every $\mathcal{P}_{\kappa}(\theta)$ has a normal fine measure. Again these facts are all absolute down to $V_{\lambda},$ so $V_{\lambda}$ thinks that $\kappa$ is supercompact.

Also by a standard elementary embedding argument, these facts about $\kappa$ and $\lambda$ imply that there are stationarily many $\alpha<\kappa$ such that $V_{\kappa}$ believes $\alpha$ to be a supercompact Vopenka cardinal.

$\endgroup$

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .