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A paper by T. Chartier, P.P. Pach and myself describing the status of "Can we color Z^+ with n colors such that a, 2a, …, na all have different colors for all a?" has just been published. Coloring the …

Kenneth Kunen passed away yesterday, August 14. Kunen is best known for his work in set theory and set-theoretic topology. https://www.math.wisc.edu/node/829

I should probably add that I find the topic of obvious mathematical interest, and the links and surrounding discussion useful. The gossip, not so much. …

Unlike what another answer suggests, I think that "continuum hypothesis" is not a good tag to use as a proxy here. Instead, I assume many of these questions would be about "cardinal characteristics" …

I did this once, here. I was going to answer the question, but Andy did it first. I still felt there was some value in the remarks I was going to add, but it felt strange to do it in a new answer, and …

A question that fascinates me is the problem of characterizing the subsets $S$ of the unit circle $\mathbb T$ for which there is a power series with radius of convergence $1$ that, on $\mathbb T$, con …

Simon Thomas asked in Ultrafilters and automorphisms of the complex field whether the existence of non-principal ultrafilters (over the natural numbers) suffices to imply the existence of a nont …

One I like very much is Can we color $\mathbb Z^+$ with $n$ colors such that $a, 2a, \dots, na$ all have different colors for all $a$? Among the failed proposed attempts, the ones that appeared …

I have discussed MO but do not participate in the site do not seem concerned with these issues, luckily, but typically indicate that their field is underrepresented; there is the beginning of a good discussion …

There are quite a few questions on the main site related to (first-order) Peano Arithmetic and its fragments. Here are two examples: 1, 2 (but there are many others). It would be nice, and feels appr …

This is motivated by this question, see also the comments, and Will Jagy's answer. I was asked to start a formal request, so here it is. A user that has expressed no desire to participate anymore on …

Please vote up if you agree that the requested undeleting is a reasonable (useful, beneficial) action for the community. Vote down otherwise.

In the old meta we had a very useful thread where one could point to moderators multiple accounts to be merged. Since things have changed, would there be a point on having such a thread here, or what …

I think we should make sure all questions and answers display correctly, even if old. [Edit: By this, I mean, necessary changes, that add clarity, should be welcome. Adding spaces, correcting trivia …

They should stay, as they add to the collegiality of the site. Editing them off accomplishes little beyond depersonalizing posts and cluttering the front page.