### Recent Writing

### Mathoverflow Activity

- Comment by Victoria Gitman on continuity points of elementary embeddings from $0^\sharp$Great! Thanks very much for the explanation!Victoria Gitman
- Comment by Victoria Gitman on continuity points of elementary embeddings from $0^\sharp$Almost got it. Why is $j'(\alpha_0)$ indiscernible?Victoria Gitman
- Comment by Victoria Gitman on continuity points of elementary embeddings from $0^\sharp$I don't see why $j$ has to be an ultrapower embedding. Is this obvious?Victoria Gitman

- Comment by Victoria Gitman on continuity points of elementary embeddings from $0^\sharp$
### Cantor’s Attic

- Feferman-Schütte← Older revision Revision as of 08:49, 22 May 2018 (2 intermediate revisions by the same user not shown)Line 27: Line 27: (For $\alpha \lt \beta$, the fixed point sets of $\varphi_\alpha$ are all closed sets, and so their intersection is closed; it is unbounded because $\cup_\alpha \varphi_\alpha(t+1)$ is a common fixed point greater than […]Denis Maksudov
- User:UbersketchCreated page with "Ubersketch - Arithmologist. Hello there." New pageUbersketch - Arithmologist. Hello there.Ubersketch
- Fast-growing hierarchy← Older revision Revision as of 14:31, 20 May 2018 Line 139: Line 139: \(f_{\varepsilon_0}(n-1) ≤ H_{\varepsilon_0}(n) ≤ f_{\varepsilon_0}(n+1)\) for all \(n ≥ 1\). \(f_{\varepsilon_0}(n-1) ≤ H_{\varepsilon_0}(n) ≤ f_{\varepsilon_0}(n+1)\) for all \(n ≥ 1\). −The [[slow-growing hierarchy]] "catches up" to the fast-growing hierarchy only at \(\psi_0(\Omega_\omega)\), using [[Buchholz's ψ functions]].+The [[slow-growing hierarchy]] "catches up" to […]Denis Maksudov
- Slow-growing hierarchy← Older revision Revision as of 14:29, 20 May 2018 Line 16: Line 16: −If \(\alpha=\varepsilon_0\) then \(\alpha[0]=0\) and \(\alpha[n+1]=\omega^{\alpha[n]}\).+If \(\alpha=\varepsilon_0\) then \(\alpha[0]=1\) and \(\alpha[n+1]=\omega^{\alpha[n]}\). Using this system of fundamental sequences we can define the slow-growing hierarchy up to \(\varepsilon_0\) and we have \(g_{\varepsilon_0}(n) = n \uparrow\uparrow n \) Using this system of […]Denis Maksudov
- Hardy hierarchy← Older revision Revision as of 10:51, 20 May 2018 Line 28: Line 28: There are much stronger systems of fundamental sequences you can see on the following pages: There are much stronger systems of fundamental sequences you can see on the following pages: − +*[http://googology.wikia.com/wiki/List_of_systems_of_fundamental_sequences List of systems of fundamental sequences] *[[Madore's ψ function]] *[[Madore's ψ […]Denis Maksudov

- Feferman-Schütte

# Category Archives: web

## A WikiBibtex extension for MediaWiki

A few years ago, Joel Hamkins and myself started a Wiki about infinity, meaning large cardinals, called Cantor’s Attic. Resource wise, it is easy enough to start a Wiki. You just need a hosting service, for which we chose DreamHost, … Continue reading

## Julia sets and the Mandelbrot set

This is a talk at the City Tech Math Club, April 19, 2012.

## Introducing Cantor’s Attic

Two months ago, Joel Hamkins approached me about collaborating on creating a wiki for notions of infinity of all breeds and scales. Joel said that his motivation came from the excellent Complexity Zoo wiki started by Scott Aaronson (the zookeeper) … Continue reading