Recent Questions - MathOverflow Metamost recent 30 from meta.mathoverflow.net2019-10-16T21:07:03Zhttp://meta.mathoverflow.net/feedshttps://creativecommons.org/licenses/by-sa/4.0/rdfhttps://meta.mathoverflow.net/q/436836How much is MathOverflow exposed to recent events on StackExchange?Burn this accounthttps://meta.mathoverflow.net/users/1471122019-10-12T00:56:28Z2019-10-15T23:26:20Z
<p>[Long-time 10k+ MO user here, asking this question anonymously for reasons that should be obvious.
<strong>Added Oct 16: My access to this account will self-destruct in 3, 2, 1 ....</strong> (sorry, won't be able to accept an official answer. For what it's worth, I strongly support Tim Campion's suggestion.)]</p>
<blockquote>
<p>This question is <strong>not</strong> meant to be a place to discuss the pros and cons of the dumpster fire on meta.SE, or the underlying issues that started it. Go there if you want to get depressed. Also, I think that <strong>only moderators are in a position to answer this question.</strong></p>
</blockquote>
<p>The short background is that StackExchange Inc. 1) is trying to implement a new Code of Conduct (CoC), and it's proving difficult, and 2) has retroactively relicensed <em>all</em> existing content, questioned by many as being of dubious legality. These are separate issues, but have both contributed to a wide feeling (expressed through community voting and extensive commenting) that SE Inc. is making a mess of things, one way or another.</p>
<p>Since MathOverflow uses the SE platform, but is actually <a href="https://meta.mathoverflow.net/questions/969/who-owns-mathoverflow">a different organisation</a> it is not clear what exposure (in the sense of risk) MO has to the recent controversies. Are our moderators bound by the same agreement as the SE network moderators? Will the CoC apply here, when it is finally sorted out? Were contributions to MO retroactively relicensed (making <a href="https://meta.mathoverflow.net/questions/950/who-owns-my-mathoverflow-posts">this question</a> outdated)?</p>
<p>Again, the intent of this question is not the <em>content</em> of the CoC or the relicensing issue, but to get in writing the facts of where MO stands in relation to these from a contractual/legal/etc way.</p>
<hr>
<p><strong>Edit</strong> (To clarify some things) I asked this question in a slightly vague way, partly because I didn't want to pre-empt any position or bring up debates here. But I've read a bit more, and Johannes pointed out some relevant facts in an answer. So here are some more focussed questions. Again, this is <strong>not to debate the merit or otherwise of the below points</strong>, I'm looking for official answers from mods or MO owners/board members on policy about changes that StackExchange Inc makes.</p>
<ul>
<li><p>StackExchange relicensed all contributions users had made to their websites (from CC-By-SA 3.0 to CC-By-SA 4.0, which change the CC people say can't be made without permission), but this has also relicensed all MathOverflow content too. Is this compatible with <a href="https://drive.google.com/file/d/1-Rx93qiEH3t9wAwsyvuVzjawF62X6OgI/view" rel="nofollow noreferrer">the agreement between the MathOverflow corporation and StackExchange Inc</a>?</p></li>
<li><p>I presume that there is very little objection to the principles of the new Code of Conduct (CoC), and find it nigh-impossible to forsee any circumstances in which MathOverflow as an organisation would object to the now in-position wording, and adopting the CoC as official here (were it a choice). However, the official FAQ on the CoC, which has given rise to concerns among many StackExchange users, is getting rather distant from any document that I can see referred to under the legal agreement between MathOverflow and StackExchange Inc. The CoC is linked to from MathOverflow pages, and so is, it seems, in effect and binding. I haven't seen, after some cursory clicking about, explicit links from MathOverflow to the contentious FAQ. Does this latter nonetheless carry force on MathOverflow to the extent it does on the StackExchange network? Will all future policy changes in the same manner also immediately and automatically apply on MathOverflow? (Added: I note that this type of question was raised <a href="https://meta.mathoverflow.net/questions/969/who-owns-mathoverflow#comment4931_970">nearly six years ago</a>, to which it seems the official answer was, to paraphrase, MathOverflow has an informal understanding with StackExchange Inc that SE Inc employees shouldn't interfere with our moderation as we can choose to leave the network. However, this seems to me to be a bit like <a href="https://www.youtube.com/watch?v=JKbDKsNsjac" rel="nofollow noreferrer">the nuclear deterrent</a>...)</p></li>
</ul>
<p>Perhaps all of this is moot. But I hope MathOverflow is not hit with the same <s>ugly stick</s> terrible optics that StackExchange Inc has encountered in trying to create an environment that once was expressed through 'be nice'.</p>
https://meta.mathoverflow.net/q/43670Should this be moved to math.stackexchange?frogeyedpeashttps://meta.mathoverflow.net/users/465362019-10-11T20:43:35Z2019-10-12T17:54:52Z
<p>I posted <a href="https://mathoverflow.net/q/343659">Lower bound on Carmichael Function</a></p>
<p>and just assumed it belonged here, but after thinking about it for some time I'm not so sure. The Carmichael function itself might be encountered by other enthusiasts, so it could be nice to have this on the math.se site, but this question particularly asks for the state of the art and any references known so it felt fitting for the research half of the math community.</p>
https://meta.mathoverflow.net/q/436610What to do if you want up-to-date answers to an old question on technologyBen Websterhttps://meta.mathoverflow.net/users/662019-10-10T14:05:39Z2019-10-13T15:21:12Z
<p>One issue with the site lasting as long as it has is that technology has changed quite a bit since its early days, and so discussions of technology are extremely out of date. In particular, when doing some research of my own on online collaboration tools, I encountered the question <a href="https://mathoverflow.net/questions/49384/tools-for-long-distance-collaboration">Tools for long-distance collaboration</a>, which I'm sure was very useful in 2010, but is pretty irrelevant now. </p>
<p>I'm sure to get people's thoughts on what to do if you want up-to-date answers to these questions. Post essentially the same question, but add "except for a decade later"? Decide that questions that involve specifics of technology aren't a good fit for the site? </p>
https://meta.mathoverflow.net/q/4363-1Should there be another tag for vector bundles in Algebraic geometry (over schemes)?Praphulla Koushikhttps://meta.mathoverflow.net/users/1186882019-10-03T16:38:13Z2019-10-03T23:42:07Z
<p>Should there be another tag for vector bundles in Algebraic geometry (over schemes)?</p>
<p><a href="https://mathoverflow.net/questions/343060/zero-section-of-quasi-coherent-bundle">Some</a> <a href="https://mathoverflow.net/questions/342897/global-section-module-of-algebraic-vector-bundles-on-the-punctured-spectrum-of-a">questions</a> <a href="https://mathoverflow.net/questions/341627/beauville-laszlo-for-schemes">about</a> vector bundles in the sense of algebraic geometry are given the <a href="https://mathoverflow.net/questions/tagged/vector-bundles">tag</a> whose <a href="https://mathoverflow.net/tags/vector-bundles/info">tag description</a> says </p>
<blockquote>
<p>A continuously varying family of vector spaces of the same dimension over a topological space. If the vector spaces are one-dimensional, the term line bundle is used and has the associated tag line-bundles.</p>
</blockquote>
<p>So, the question is, is it a better idea to create another tag for vector bundles in the sense of algebraic geometry?</p>
https://meta.mathoverflow.net/q/43596Why can't I post my question on MO anymoregetehttps://meta.mathoverflow.net/users/1168572019-10-02T17:22:22Z2019-10-03T06:58:16Z
<p>It seems that my account in MO has been blocked. My post is no more accepted, saying that </p>
<blockquote>
<p>we are no more accepting post from this account.</p>
</blockquote>
<p>How can I get my account unblocked? </p>
https://meta.mathoverflow.net/q/43566MathOverflow in the newsshane.orourkehttps://meta.mathoverflow.net/users/225992019-09-30T20:54:38Z2019-10-01T11:37:18Z
<blockquote>
<p>What are some instances of MathOverflow being mentioned in the media?</p>
</blockquote>
<p>Now that MathOverflow has recently had its tenth anniversary, I would be interested to learn of any mentions of it in the mass media. I'm interested in what the world outside MO, and indeed outside mathematics, has to say about MO, possibly prompted by its tenth anniversary, but I would also like to know of any such mentions in general over the last decade.</p>
<p>There is one article in the Notices of the American Mathematical Society <a href="https://www.ams.org/notices/201006/rtx100600701p.pdf" rel="nofollow noreferrer">from 2010</a>, and some others mentioned in <a href="https://meta.mathoverflow.net/questions/3154/mo-in-the-notices-of-the-ams">this question</a> and <a href="https://meta.mathoverflow.net/questions/3154/mo-in-the-notices-of-the-ams/3155#3155">Gerry Myerson's answer</a> to it. When I search on the New York Times online for 'mathoverflow', <a href="https://www.nytimes.com/search?query=mathoverflow" rel="nofollow noreferrer">three articles are listed</a>, but they don't seem to be accessible without a subscription. A similar search of a handful of other newspaper sites (Washington Post, Irish Times, Guardian, Neue Zürcher Zeitung, Le Monde, El País, Sydney Morning Herald) finds them remarkably quiet on the subject.</p>
<p>I see that the idea of having a meta question 'MathOverflow in the News', whose answers could list mentions in the media, was <a href="https://meta.mathoverflow.net/questions/563/where-to-share-mathoverflow-success-stories/567#567">raised by Joel David Hamkins</a> some years ago but I haven't been able to see it if it was ever followed up. If it was, perhaps somebody could provide a link to it; if not, perhaps this question could prompt such a list of media coverage.</p>
https://meta.mathoverflow.net/q/435311Happy tenth anniversary! How did you celebrate?Gerhard Pasemanhttps://meta.mathoverflow.net/users/34022019-09-28T15:11:38Z2019-10-08T10:51:44Z
<p>Question 1 was a test question posted about ten years ago from this one (give or take about an hour). There's been a bit going on since then with the main forum. This post is a place for celebrants to respond with what they did. If others want to leave personal reflections on MathOverflow's 10th anniversary, answer posts on that are also welcome.</p>
<p>So how do you/did you celebrate MathOverflow?</p>
<p>Gerhard "The Party Isn't Over Yet" Paseman, 2019.09.28.</p>
https://meta.mathoverflow.net/q/435136How to cite comment by unknown user disproving Erdős conjecture?domotorphttps://meta.mathoverflow.net/users/9552019-09-25T19:22:39Z2019-09-25T20:20:56Z
<p>I believe that fedja has disproved a conjecture of Erdős et al. when commenting on my question <a href="https://mathoverflow.net/questions/300604/almost-monochromatic-point-sets">Almost monochromatic point sets</a>, but I'm unable to contact fedja regarding this. What shall I do? Shall I just casually drop a footnote in my upcoming paper that an unknown user has solved an Erdős problem?</p>
https://meta.mathoverflow.net/q/43492Wouldn't it be nice to have subforums on MathOverflow dedicated to learning certain books/papers/etc.?Kimhttps://meta.mathoverflow.net/users/1265432019-09-24T19:37:11Z2019-09-24T23:42:06Z
<p>Oftentimes, I read something and start to ponder questions of the form "Does the formula on pg. 87 have a typo?" or "Isn't this a gap in the proof?" or "Why does the definition have this extra assumption?", etc. Learning questions which I would generally consider a bit too specific or trivial to post on MathOverflow but I wished did have an answer out there. And I suspect others reading the same thing may have also wondered about it.</p>
<p>If there was a subforum dedicated specifically to book X or paper Y, then I wouldn't hesitate to ask. It would be nice for people studying the same thing to have a central place to exchange ideas about it. And MathOverflow seems like an ideal venue for this kind of thing.</p>
<p>Would such an idea be feasible with the current engine? Allowing people to create subforums in the site dedicated to fielding specific books and papers, that is.</p>
https://meta.mathoverflow.net/q/43465Mathematics and MathOverflow relationshipbluehttps://meta.mathoverflow.net/users/1460922019-09-19T18:51:15Z2019-09-21T21:00:50Z
<p>Is there a connection between Mathematics and MathOverflow sites? Obviously topics are similar, but I mean something like: do questions posted on one site, perhaps with certain tags, automatically end up on the other one? I have seen in the past same questions posted on both sites at the same time and I was wondering if users did it manually or not.</p>
<p>Also, how do I decide what topics are for overflow and what are for regular site? I know that calculating a basic limit should be on the regular site, but there are some questions that I'm not sure about. Should I post those on both sites?</p>
<p>I hope I'm posting this at the right place 😁
Thanks in advance</p>
https://meta.mathoverflow.net/q/434411What should the tag (open-problems) be used for?Martin Sleziakhttps://meta.mathoverflow.net/users/82502019-09-07T08:41:00Z2019-09-13T11:24:54Z
<p>Since this issue came up in comments to <a href="https://meta.mathoverflow.net/questions/4343/making-open-problems-tag">another questions on meta</a>, I'll ask about the intended issue of the <a href="https://mathoverflow.net/questions/tagged/open-problems" class="post-tag" title="show questions tagged 'open-problems'" rel="tag">open-problems</a> tag.</p>
<p><strong>Question.</strong> What is the intended usage of the <a href="https://mathoverflow.net/questions/tagged/open-problems" class="post-tag" title="show questions tagged 'open-problems'" rel="tag">open-problems</a> tag? Should it be used for questions related to some <em>specific</em> open problem? Should it be used for <em>lists</em> of open problems? Or are both usages admissible? </p>
<p>If there is some consensus how the tag is supposed to be used, possibly the tag-info might be improved based on that.</p>
<p>Some information related to the tag in question that I was able to find (and which could also help explain why I see current guidelines on the usage of this tag as unclear):</p>
<ul>
<li>If we check how the tag is currently used in practise, people use it for both possibilities. (For example, there are <a href="https://mathoverflow.net/questions/tagged/open-problems+big-list">26 questions tagged open-problems+big-list</a>.)</li>
<li>If you look <a href="https://mathoverflow.net/tags/open-problems/info">at the tag-info</a> (here are the links to the current revisions of the <a href="https://mathoverflow.net/revisions/135660/2">tag-excerpt</a> and <a href="https://mathoverflow.net/revisions/135659/2">the tag-wiki</a>), it does not exclude either of the two possibilities, although it does not mention <em>lists</em> of open problems.</li>
<li>However, it was pointed out in an older post on meta that the formulation in the tag-info was taken from the old FAQ and some users considered the description in the tag-info outdated: <a href="https://meta.mathoverflow.net/q/360">What should be the policy on “open problems” on MO?</a> (See also comments under <a href="https://meta.mathoverflow.net/questions/203/frequently-asked-questions-mathoverflow-faq/205#205">the corresponding FAQ entry</a>. The post about open problem policy was made in July 2013, shortly after <a href="https://mathoverflow.net/posts/135660/revisions">the tag-info was created</a>.)</li>
<li>At some point in the past, the tag was called <a href="https://mathoverflow.net/questions/tagged/open-problem" class="post-tag" title="show questions tagged 'open-problem'" rel="tag">open-problem</a> - in Wayback Machine I was able to find a snapshot <a href="http://web.archive.org/web/20170715054657/https://mathoverflow.net/questions/tagged/open-problem" rel="nofollow noreferrer">from July 2017</a> with the old name. It was changed to the plural at some point <a href="https://chat.stackexchange.com/transcript/10243?m=40567366#40567366">by a moderator</a>.</li>
<li>In the past, there used to be a separate <a href="https://mathoverflow.net/questions/tagged/open-problem-list" class="post-tag" title="show questions tagged 'open-problem-list'" rel="tag">open-problem-list</a> tag. Wayback Machine shows 42 questions in this tag <a href="http://web.archive.org/web/20170310163429/https://mathoverflow.net/questions/tagged/open-problems-list" rel="nofollow noreferrer">in March 2017</a>. In October 2017 <a href="https://meta.mathoverflow.net/questions/194/help-improve-tagging/3433#3433">Alexander Chervov asked on meta</a> where this tag disappeared. It seems that it was <a href="https://chat.stackexchange.com/transcript/10243?m=40565329#40565329">merged into open-problem(s) by a moderator</a>.</li>
<li>You can find <a href="https://chat.stackexchange.com/rooms/10243/conversation/about-open-problems-list-tag">a longer conversation in chat</a> related to these two tags - (open-problems) and (open-problem-list). This is where I learned about the merges and renames I mention above. The moderator who handled these actions <a href="https://chat.stackexchange.com/transcript/10243?m=40567366#40567366">said there that</a>: "In any case, using <a href="https://mathoverflow.net/questions/tagged/open-problems" class="post-tag" title="show questions tagged 'open-problems'" rel="tag">open-problems</a> for specific problems is a meta usage and shouldn't be encouraged. I remember adding the plural form in an attempt to discourage this." And <a href="https://chat.stackexchange.com/transcript/10243?m=40565329#40565329">in another chat message</a>: "using <a href="https://mathoverflow.net/questions/tagged/open-problems" class="post-tag" title="show questions tagged 'open-problems'" rel="tag">open-problems</a> for specific open problems makes it a "meta-tag", the correct usage is what you intend (whether the intent is a list or something else is to be clarified in the question)." Although <em>shouldn't be encouraged</em> is not too strong phrase, from this it seems that the moderators are in favor of using this tag for <em>lists of open problems</em> rather than using the tag for questions concerning <em>single</em> open problem. (Or at least this particular moderator.)</li>
</ul>
<hr>
<p>For the users who are unfamiliar with this terminology, I'll add that the phrase <em>meta tag</em> is used here to mean a tag based not on mathematical content of the question, but describing some feature of the question. (Examples might be tags such as <a href="https://mathoverflow.net/questions/tagged/big-list" class="post-tag" title="show questions tagged 'big-list'" rel="tag">big-list</a>, <a href="https://mathoverflow.net/questions/tagged/reference-request" class="post-tag" title="show questions tagged 'reference-request'" rel="tag">reference-request</a>, <a href="https://mathoverflow.net/questions/tagged/textbook-recommendation" class="post-tag" title="show questions tagged 'textbook-recommendation'" rel="tag">textbook-recommendation</a>, <a href="https://mathoverflow.net/questions/tagged/soft-question" class="post-tag" title="show questions tagged 'soft-question'" rel="tag">soft-question</a>, <a href="https://mathoverflow.net/questions/tagged/big-picture" class="post-tag" title="show questions tagged 'big-picture'" rel="tag">big-picture</a>.) I do not know about some post which offers more details about meta tags (in this sense) on MathOverflow Meta, but you can find Willie Wong's post on Mathematics Meta useful if you want to read a bit more about them: <a href="https://math.meta.stackexchange.com/q/2498">The “meta-tags”.</a>. There is also a blog post <a href="https://stackoverflow.blog/2010/08/07/the-death-of-meta-tags/">The Death of Meta Tags</a> on Stack Overflow blog.</p>
https://meta.mathoverflow.net/q/43404Garbled MathJax in a link to a question with MathJax in the titleმამუკა ჯიბლაძეhttps://meta.mathoverflow.net/users/412912019-09-05T18:53:46Z2019-09-06T06:22:32Z
<p>The following occurs on my activity page:</p>
<p><a href="https://i.stack.imgur.com/FpHGT.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/FpHGT.png" alt="enter image description here"></a></p>
<p>The question it links to is <a href="https://mathoverflow.net/q/286626/41291">Is there an explicit expression for Chebyshev polynomials modulo $x^r-1$?</a> and it seems that the MathJax in the end somehow got superimposed at the beginning of the link text.</p>
<p>This happens on Windows 10, Chrome 76.0.3809.132 (64-bit)</p>
<p>Don't know if this might be useful for anything but when I right-click on the link that superimposed thing disappears.</p>
<p>Maybe I should add this issue to the <a href="https://meta.mathoverflow.net/q/598/41291">List of recurrent technical problems involving MathJax</a> but it seems not to satisfy conditions given there.</p>
https://meta.mathoverflow.net/q/433912Can we get rid of the "featured on meta" main meta links?Federico Polonihttps://meta.mathoverflow.net/users/18982019-09-03T11:37:11Z2019-09-24T17:13:15Z
<p>As you know, MathOverflow has a special status in the Stack Exchange family, and (by a special agreement) it doesn't display any kind of ads nor links to the hot network questions in the sidebar.</p>
<p>Would it be possible to remove also the links to the global meta questions in the "featured on meta" top-right sidebar? For instance currently I would remove the two top links, leaving only the third one.</p>
<p><a href="https://i.stack.imgur.com/C37ej.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/C37ej.png" alt="enter image description here"></a></p>
<p>I don't find them particularly useful. To me they are just fluff and they make <em>our</em> meta questions stand out less; they take up premium space in the top right part of the page "above the fold". </p>
<p>Also, under a suitable interpretation of the expression, arguably they can be considered "internal advertisements", and so they would be forbidden by the <a href="https://drive.google.com/file/d/1-Rx93qiEH3t9wAwsyvuVzjawF62X6OgI/view" rel="nofollow noreferrer">agreement</a> between MO and SE, which can be found <a href="https://meta.mathoverflow.net/questions/969/who-owns-mathoverflow/970#970">in this answer by François G. Dorais♦</a>. The relevant part is:</p>
<blockquote>
<ol start="5">
<li>It is understood that MathOverflow shall consider in the future the placement of certain announcement services like job listing in the future. Stack Exchange shall not run advertisements, including internal advertisements, on MathOverflow 2.0 (or any subsequent version thereof), without specific and advance written consent of the MathOverflow.</li>
</ol>
</blockquote>
<p>EDIT: everything I wrote applies also to the SE blog entries:</p>
<p><a href="https://i.stack.imgur.com/rP493.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rP493.png" alt="enter image description here"></a></p>
https://meta.mathoverflow.net/q/433711Can I ask about entry-level questions (understanding and definitions) of research-level topics?triscthttps://meta.mathoverflow.net/users/1432842019-09-02T06:08:43Z2019-09-02T18:27:59Z
<p>I am currently doing a reading on Teichmuller space and I am having trouble understanding some basic definitions. So I asked these two questions on MSE first:</p>
<p><a href="https://math.stackexchange.com/questions/3341079/understanding-teichmuller-equivalence-of-marked-compact-riemann-surfaces">Understanding Teichmuller equivalence of marked compact Riemann surfaces</a></p>
<p><a href="https://math.stackexchange.com/questions/3340739/what-is-the-sobolev-space-of-maps-between-surfaces">What is the Sobolev space of maps between surfaces</a></p>
<p>They have received some upvotes so they are at least not bad questions. The fact that it hasn't been a day since I posted them might make me seem a little too thirsty for answers, but the thing is, while I was reading Riemann surfaces as a preparation for Teichmuller spaces (like a month ago), I have asked even simpler questions, yet those questions have not received a single answer. Judging from the views they've received, I think I have a pretty good reason to believe my new questions are going to end up just like the old ones. And I don't want to waste any more time waiting for nothing.</p>
<p>Based on that, I would like to know whether it is appropriate to ask these questions (more generally speaking, questions that are not of the form of research questions, but belong to a research-level topic) on this site. Thanks!</p>
https://meta.mathoverflow.net/q/43360Would this soft question be appropriate?Robin Saundershttps://meta.mathoverflow.net/users/43362019-09-01T15:37:38Z2019-09-01T15:37:38Z
<p>A few weeks back on the Math Stack Exchange, I asked <a href="https://math.stackexchange.com/questions/3317170/what-conditions-constrain-pdes-which-are-studied-in-practice">this question</a> about "interesting" PDEs. It got (no answers and) some deserved criticism, so I opened <a href="https://math.meta.stackexchange.com/questions/30569/was-this-soft-question-appropriate">a discussion on the Meta there</a> and made some pretty big edits in response to feedback, without changing the question I'd intended to ask. There hasn't been much feedback since then, and in particular still no answers.</p>
<p>This all leaves me with no sense of whether </p>
<ul>
<li>the (soft) question I actually meant to ask was bad,</li>
<li>the presentation was still unacceptable after my edits,</li>
<li>anything else.</li>
</ul>
<p>I got a hunch that reposting the question here might get better results, but am aware that at least the presentation is still less than ideal (that's never been my strong suit) and maybe there's just nothing salvageable. So, I'd be very grateful for any and all advice.</p>
https://meta.mathoverflow.net/q/43339Suggested tag: approximation-propertyJ. van Dobben de Bruynhttps://meta.mathoverflow.net/users/1202512019-08-28T20:39:34Z2019-08-29T20:46:32Z
<p>I'm relatively new to MO (but have been on MSE for a longer time), which means that I don't have enough reputation to create new tags. Which is probably a good thing.</p>
<p>Lately I've been puzzling with Banach space tensor products and the approximation property, and on multiple occasions found that my search would have been easier if there had been a tag for questions related to the approximation property. It is my impression that it is a whole field of its own, with a rich body of theory and (especially) counterexamples, so to me a tag <code>approximation-property</code> would make sense.</p>
<p>Since I understand that we don't want to go haphazardly creating new tags for every specialization (or niche) within mathematics, I thought I'd ask what you think. Has this been considered before? Do we like the idea? Do we hate it? Should we consider variations on the proposal (e.g. a tag <code>metric-theory-of-tensor-products</code>)?</p>
<hr>
<p>Added later: as per François' suggestion, here is my suggested tag info.</p>
<blockquote>
<p>For questions relating to various approximation properties in functional analysis and (abstract) harmonic analysis, including approximation properties of Banach spaces, locally convex spaces, operator algebras, and locally compact groups.</p>
</blockquote>
<p>Furthermore, I tried to compile a list of questions to which the new tag would apply. Note that this list might be incomplete, again because I found it difficult to find all relevant questions on this topic. (Some would only mention the term "AP", so those would be hard to track down. This applies to one of the questions below – I only found it because it happened to be linked to another question on my list.)</p>
<p><em>Questions directly related to the approximation property (sorted by publication date).</em></p>
<ul>
<li><p><a href="https://mathoverflow.net/questions/17801/approximation-property">Approximation Property</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/31537/banach-lattice-with-ap-but-without-bap">Banach lattice with AP but without BAP?</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/32147/examples-of-groups-without-the-n-positive-approximation-property">Examples of groups without the n-positive approximation property</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/39808/are-the-compact-and-haagerup-approximation-properties-equivalent">Are the compact and Haagerup approximation properties equivalent?</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/136350/what-approximation-property-does-the-space-of-schatten-p-class-operators-have">What Approximation Property does the space of Schatten-p class operators have?</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/139545/the-approximation-property-of-group-c-algebras">The approximation property of group C*-algebras</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/179493/a-question-on-p-approximation-property">A question on $p$-approximation property</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/191919/c-algebra-generated-by-those-operators-that-are-bounded-on-every-ell-p">$C^*$-algebra generated by those operators that are bounded on every $\ell_p$</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/196097/compact-approximation">Compact Approximation</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/196100/approximation-property-characterization">Approximation Property: Characterization</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/196110/approximation-property-decomposition">Approximation Property: Decomposition</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/196155/a-question-on-metric-characterization-of-approximation-property">A question on metric characterization of approximation property</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/198466/ultraweak-topology-on-bx-is-the-map-x-otimes-x-bx-isometric">Ultraweak topology on B(X): Is the map X\otimes X* -> B(X)* isometric?</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/199122/does-the-approximation-property-ap-pass-to-quotients-by-amenable-subgroups">Does the Approximation Property (AP) pass to quotients by amenable subgroups?</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/202835/for-discrete-groups-does-the-haagerup-property-imply-the-ap-of-haagerup-kraus">For discrete groups, does the Haagerup property imply the AP of Haagerup-Kraus?</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/212566/is-there-a-quotient-of-c-0-without-the-approximation-property">Is there a quotient of $c_0$ without the approximation property?</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/230707/weakenings-of-the-bounded-approximation-property">Weakenings of the Bounded Approximation Property</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/237804/compact-non-nuclear-operators">Compact non-nuclear operators</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/254473/a-variant-of-the-approximation-property">A variant of the approximation property?</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/254496/does-the-banach-algebra-of-jets-have-the-approximation-property">Does the Banach algebra of jets have the approximation property?</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/263904/cbap-for-the-full-group-c-algebra">CBAP for the full group $C^*$-algebra</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/265130/tensors-and-nuclear-fredholm-operators">Tensors and Nuclear/Fredholm Operators</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/278184/the-approximation-property-for-some-spaces-of-holomorphic-functions">The approximation property for some spaces of holomorphic functions</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/291015/completely-bounded-maps-approximately-factoring-through-finite-matrices">Completely bounded maps approximately factoring through finite matrices</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/296246/does-thompsons-group-v-have-property-ap">Does Thompson's group $V$ have property AP?</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/304198/approximation-property-counterexamples-also-relation-to-tensor-products">Approximation property counterexamples? (Also: relation to tensor products)</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/327888/a-characterization-of-nuclear-functionals-in-terms-of-continuity-with-respect-to">A characterization of nuclear functionals in terms of continuity with respect to some special topologies on $B(X)$?</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/337889/a-question-on-the-metric-approximation-property">A question on the metric approximation property</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/339378/do-the-operators-in-be-f-separate-points-on-the-projective-tensor-product-f">Do the operators in $B(E,F)$ separate points on the projective tensor product $F' \mathop{\tilde\otimes_\pi} E$?</a></p></li>
</ul>
<p><em>Questions tangentially related to the approximation property (sorted by publication date).</em></p>
<ul>
<li><p><a href="https://mathoverflow.net/questions/74007/projective-and-injective-tensor-product">Projective and injective tensor product</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/76604/trab-trba-part-2">tr(ab)=tr(ba), part 2.</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/171802/denseness-of-finite-rank-operators-in-mathcalbx-y">Denseness of finite rank operators in $\mathcal{B}(X,Y)$</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/201448/approximation-property-of-fr%C3%A9chet-if-range-is-restricted-to-an-embedded-hilbert">Approximation property of Fréchet if range is restricted to an embedded Hilbert space</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/206181/a-slice-map-type-problem-for-symmetric-tensors-in-the-square-of-a-nuclear-c-a">A "slice-map" type problem for symmetric tensors in the square of a nuclear C*-algebra</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/211845/noncommutative-analogs-of-classical-banach-geometric-properties">Noncommutative analogs of classical Banach geometric properties</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/220752/outline-of-generic-separable-banach-spaces-dont-have-a-schauder-basis">Outline of Generic Separable Banach Spaces don't have a Schauder Basis</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/232291/do-there-exist-infinite-dimensional-banach-spaces-in-which-every-bounded-linear">Do there exist infinite-dimensional Banach spaces in which every bounded linear operator attains its norm?</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/255246/characterization-of-exact-groups-via-the-existence-of-amenable-actions-on-unital">Characterization of exact groups via the existence of amenable actions on unital C*-algebras, part 2</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/270151/on-the-relation-between-lipschitz-free-spaces">On the relation between Lipschitz free-spaces</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/271293/are-ideals-in-separable-c-algebras-complemented-subspaces">Are ideals in separable C*-algebras complemented subspaces?</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/304426/nuclear-operators-and-their-eigenvalues">Nuclear operators and their eigenvalues</a></p></li>
<li><p><a href="https://mathoverflow.net/questions/327418/when-does-the-dual-to-the-space-kx-of-compact-operators-consist-of-nuclear-f">When does the dual to the space $K(X)$ of compact operators consist of nuclear functionals?</a></p></li>
</ul>
<p><em>Questions containing the term "approximation property" which nevertheless fall outside the scope of the proposed tag (mostly regarding different approximation properties, e.g. in algebra or logic).</em></p>
<ul>
<li><a href="https://mathoverflow.net/questions/50570/real-approximation-for-homogeneous-spaces-of-linear-algebraic-groups">Real approximation for homogeneous spaces of linear algebraic groups</a></li>
<li><a href="https://mathoverflow.net/questions/51263/infinitely-many-solutions-of-a-diophantine-equation">Infinitely many solutions of a diophantine equation</a></li>
<li><a href="https://mathoverflow.net/questions/68442/what-could-be-some-potentially-useful-mathematical-databases">What could be some potentially useful mathematical databases?</a></li>
<li><a href="https://mathoverflow.net/questions/80904/class-number-of-pgl-2">Class number of PGL_2</a></li>
<li><a href="https://mathoverflow.net/questions/93303/are-there-lightweight-foundations-for-arbitrarily-extendable-objects">Are there lightweight foundations for arbitrarily extendable objects?</a></li>
<li><a href="https://mathoverflow.net/questions/105080/analytic-elements-in-non-archimedean-geometry">Analytic elements in non-archimedean geometry</a></li>
<li><a href="https://mathoverflow.net/questions/141857/is-there-a-truth-approximation-on-a-cumulative-hierarchy">Is there a truth approximation on a cumulative hierarchy?</a></li>
<li><a href="https://mathoverflow.net/questions/172081/a-cohomology-group-which-depends-on-the-connection">A cohomology group which depends on the connection</a></li>
<li><a href="https://mathoverflow.net/questions/191071/preserving-jonsson-cardinals">Preserving Jonsson cardinals</a></li>
<li><a href="https://mathoverflow.net/questions/286055/the-delta-approximation-property-for-ground-models">The $\delta$-approximation property for ground models</a></li>
<li><a href="https://mathoverflow.net/questions/325806/if-the-finitely-additive-measure-of-an-open-set-is-approximable-by-clopen-sets">If the finitely additive measure of an open set is approximable by clopen sets, is it approximable from within?</a></li>
</ul>
https://meta.mathoverflow.net/q/433112Appropriateness of proposed question on applications of number theory in dynamical systems?J Whttps://meta.mathoverflow.net/users/23122019-08-20T13:51:47Z2019-08-26T16:31:00Z
<p><strong>Update: the question has now been asked on the main site - <a href="https://mathoverflow.net/q/339214/2312">Applications of number theory in dynamical systems</a></strong></p>
<p>I am considering asking a reference-request type question on MO about significant and/or recent applications of number theory in dynamical systems/nonlinear dynamics. I see possible overlap with arithmetic dynamics (interesting in its own right - see <a href="https://arxiv.org/abs/1806.04980" rel="nofollow noreferrer">https://arxiv.org/abs/1806.04980</a> for recent progress), but I am angling more at traditional dynamical systems theory.</p>
<p>Note that Lagarias writes in <a href="https://books.google.nl/books?id=j-pLi01XbFUC&lpg=PA35&ots=tWm34HMayA&dq=dynamical%20systems%20number%20theory&lr&pg=PA36#v=onepage&q&f=false" rel="nofollow noreferrer">The Unreasonable Effectiveness of Number Theory</a>, Proceedings of Symposia in Applied Mathematics, Volume 46, 1992, American Mathematical Society in the Chapter <em>Number Theory and Dynamical Systems</em>: "Number theoretic problems have occurred repeatedly in dynamical systems". Is this still true in the last twenty years or so? (In the question itself, I could summarize or at least list some topics, including small divisors, continued fractions, Farey sequences, Diophantine approximation, etc.)</p>
<p>Would the above be appropriate on MO? If not, how could the question be improved to make it suitable, if possible?</p>
<p><em>Proposed GRP 2019.08.24.</em></p>
<p>I am looking for references (or ways to find references) on significant and/or recent applications of techniques in number theory to problems in the areas of dynamical systems and nonlinear dynamics.
While there may be overlap with arithmetic dynamics ([add your arxiv example here]), I want examples leaning more towards traditional dynamical systems.</p>
<p>[Add the paragraph on Lagarias's remarks here, followed by] A citation search using this reference was unrewarding. Other nonrecent papers which might yield a successful citation search would be welcome. Also useful search terms would be accepted.</p>
https://meta.mathoverflow.net/q/432844Why was the whole math jokes thread deleted, and should it have been?Peter LeFanu Lumsdainehttps://meta.mathoverflow.net/users/22732019-08-18T23:17:41Z2019-08-19T00:05:02Z
<p>[Topic very similar to several other recent questions, but the central question is I think not a duplicate.]</p>
<p>The meta thread <a href="https://meta.mathoverflow.net/questions/4307/should-these-sexually-suggestive-jokes-be-kept-or-deleted">Should these sexually suggestive jokes be kept or deleted?</a> raised the point that the old and very popular question <a href="https://mathoverflow.net/questions/1083/do-good-math-jokes-exist">Do good math jokes exists?</a> included some rather sexist jokes, and proposed deleting these. The thread showed that sizeable fractions of the community both supported and opposed deleting the sexist jokes, with probably a majority supporting deletion but no clear consensus.</p>
<p>In the wake of that thread, though, something much more drastic happened: the whole question was deleted. As far as I can see, nothing in the meta discussion about the sexist jokes either gives a substantial argument for deleting the whole question, nor shows significant community support for doing so.</p>
<p>The post-deletion meta thread <a href="https://meta.mathoverflow.net/questions/4317/catering-to-professional-appearance-a-bit-much">Catering to professional appearance a bit much?</a> raises the issue in very general terms, but I’d like to ask more specifically: <strong>What arguments do people see for or against the deletion of the whole math jokes thread?</strong></p>
<p>Please note that I <em>don’t</em> want to reopen the discussion about the sexist jokes specifically: firstly it’s been discussed at length already, and secondly, deleting the sexist jokes doesn’t necessitate deleting the whole question, so arguments for deleting them are not in general arguments for deleting the rest.</p>
<p>(Full disclosure of my own stance: I strongly support the deletion of the sexist jokes; but I think the deletion of the whole thread is a loss to MO, and I’m baffled that it was done in the absence of much significant support from the community.)</p>
https://meta.mathoverflow.net/q/43252Collaborate to answerBullet51https://meta.mathoverflow.net/users/1254982019-08-17T16:41:51Z2019-08-17T16:41:51Z
<p><strong>Question:</strong> If the question is about proving <span class="math-container">$P$</span>, which, pointed out in comments, follows from <span class="math-container">$Q$</span> and <span class="math-container">$R$</span>. Is it acceptable to write an answer only containing the proof of <span class="math-container">$Q$</span>, as part of collaboration?</p>
<p>This is what I have encountered in <a href="https://mathoverflow.net/questions/338464/an-upper-bound-on-the-minimum-number-of-vertices-in-a-girth-5-graph-of-chromatic">this question</a>. I proposed a random graph model, and what remains is to show that </p>
<ul>
<li><span class="math-container">$Q$</span>: It has girth 5, and</li>
<li><span class="math-container">$R$</span>: It has unbounded chromatic number.</li>
</ul>
<p>I can prove the graph has girth 5 with high probablity under my model, but I'm not sure whether they have unbounded chromatic number. Maybe someone can prove <span class="math-container">$R$</span>, and it would complete the answer.</p>
https://meta.mathoverflow.net/q/432314Links with IP adresses rather than website namesMartin Sleziakhttps://meta.mathoverflow.net/users/82502019-08-15T07:38:37Z2019-08-21T00:04:13Z
<p>I have noticed several posts with links to pdf files where IP address is used instead of domain name the url.<sup>1</sup> (I will list them below.) Several of them seem to be dead. Moreover, this type of url seemed unusual to me. So I wanted to ask a few thinks about them:</p>
<ul>
<li>Do they work for other users? (When I tried the links, I did not get the files. But it's possible that I am the only person with the problem.)</li>
<li>Is it possible to say whether they worked at the time when they were posted? Is it possible that the links work (or worked) only for some users?</li>
<li>Are there some advantages to posted such links rather then using the more "usual" form? Is there some plausible explanation why somebody might have posted such links by mistake?</li>
</ul>
<p>Here are the links that I found:</p>
<ul>
<li>There are several (thirteen) posts <a href="https://mathoverflow.net/search?q=url%3A%22%2A129.81.170.14%2A%22">containing url's starting with 129.81.170.14</a> <strong>[All fixed 21 Aug]</strong>. For example, <a href="http://129.81.170.14/~vhm/papers_html/final-bell.pdf" rel="nofollow noreferrer">http://129.81.170.14/~vhm/papers_html/final-bell.pdf</a>, <a href="http://129.81.170.14/~tamdeberhan/gregweb.pdf" rel="nofollow noreferrer">http://129.81.170.14/~tamdeberhan/gregweb.pdf</a>, <a href="http://129.81.170.14/~tipler/theoryofeverything.pdf" rel="nofollow noreferrer">http://129.81.170.14/~tipler/theoryofeverything.pdf</a>. Neither of those links works for me, but the links <a href="http://dauns.math.tulane.edu/~vhm/papers_html/final-bell.pdf" rel="nofollow noreferrer">http://dauns.math.tulane.edu/~vhm/papers_html/final-bell.pdf</a>, <a href="http://dauns.math.tulane.edu/~tamdeberhan/gregweb.pdf" rel="nofollow noreferrer">http://dauns.math.tulane.edu/~tamdeberhan/gregweb.pdf</a>, <a href="http://dauns.math.tulane.edu/~tipler/theoryofeverything.pdf" rel="nofollow noreferrer">http://dauns.math.tulane.edu/~tipler/theoryofeverything.pdf</a> work fine.</li>
<li>I found <a href="https://mathoverflow.net/questions/110805/fundamental-groups-and-homology-groups-of-closed-subsets-of-the-plane#110830">an answer</a> which links to <a href="http://130.44.194.100/proc/2000-128-05/S0002-9939-99-05670-1/S0002-9939-99-05670-1.pdf" rel="nofollow noreferrer">http://130.44.194.100/proc/2000-128-05/S0002-9939-99-05670-1/S0002-9939-99-05670-1.pdf</a>. This links does not work for me, while <a href="https://www.ams.org/journals/proc/2000-128-05/S0002-9939-99-05670-1/S0002-9939-99-05670-1.pdf" rel="nofollow noreferrer">https://www.ams.org/journals/proc/2000-128-05/S0002-9939-99-05670-1/S0002-9939-99-05670-1.pdf</a> works. [<strong>Fixed 16 Aug</strong>]</li>
<li>There were 3 posts <a href="https://mathoverflow.net/search?q=url%3A%22%2A131.220.77.52%2A%22">with urls containing 131.220.77.52</a>. (One of them was recently <strong>fixed</strong>: <a href="https://mathoverflow.net/posts/215306/revisions">https://mathoverflow.net/posts/215306/revisions</a>.) For example, the link <a href="http://131.220.77.52/lueck/data/ictp.pdf" rel="nofollow noreferrer">http://131.220.77.52/lueck/data/ictp.pdf</a>. Unlike that one, the link to <a href="https://www.him.uni-bonn.de/lueck/data/ictp.pdf" rel="nofollow noreferrer">https://www.him.uni-bonn.de/lueck/data/ictp.pdf</a> works for me. <strong>[All fixed 21 Aug]</strong></li>
<li>In <a href="https://mathoverflow.net/questions/112362/smallest-value-of-largest-angle-in-finite-planar-configurations/112376#112376">one answer</a> I saw a link to <a href="http://193.224.79.10/~p_erdos/1960-09.pdf" rel="nofollow noreferrer">http://193.224.79.10/~p_erdos/1960-09.pdf</a>. A working link is <a href="http://bsmath.hu/~p_erdos/1960-09.pdf" rel="nofollow noreferrer">http://bsmath.hu/~p_erdos/1960-09.pdf</a>. [<strong>Fixed 16 Aug</strong>]</li>
<li>I found <a href="https://mathoverflow.net/questions/64229/upper-bounds-on-the-permanent-of-dense-0-1-matrix">a question</a> linking to <a href="http://146.163.152.131/research/papers/sdrbounds.pdf" rel="nofollow noreferrer">http://146.163.152.131/research/papers/sdrbounds.pdf</a>. The link <a href="http://www.siue.edu/~aweyhau/research/papers/sdrbounds.pdf" rel="nofollow noreferrer">http://www.siue.edu/~aweyhau/research/papers/sdrbounds.pdf</a> seems to work fine. [<strong>Fixed 16 Aug</strong>]</li>
<li>There is <a href="https://mathoverflow.net/questions/107508/is-there-an-explicit-formula-for-the-modulus-of-an-annulus-given-a-parameterizat/107560#107560">an answer</a> linking to <a href="http://194.42.1.1/~nickp/lectncm.pdf" rel="nofollow noreferrer">http://194.42.1.1/~nickp/lectncm.pdf</a>. The corresponding url could be <a href="http://www.mas.ucy.ac.cy/~nickp/lectncm.pdf" rel="nofollow noreferrer">http://www.mas.ucy.ac.cy/~nickp/lectncm.pdf</a>. [<strong>Fixed 16 Aug</strong>]</li>
<li>There are also a few "IP-type" links in some post which do work (at least for me): <a href="http://129.187.111.185/~dieter/football.pdf" rel="nofollow noreferrer">http://129.187.111.185/~dieter/football.pdf</a>, <a href="http://129.187.111.185/~dieter/duke2.ps" rel="nofollow noreferrer">http://129.187.111.185/~dieter/duke2.ps</a>, <a href="http://129.69.211.95/pdf/mit/lcs/tm/MIT-LCS-TM-560.pdf" rel="nofollow noreferrer">http://129.69.211.95/pdf/mit/lcs/tm/MIT-LCS-TM-560.pdf</a>, <a href="http://163.14.246.20/mp/pdf/S13N26.pdf" rel="nofollow noreferrer">http://163.14.246.20/mp/pdf/S13N26.pdf</a>.</li>
</ul>
<p><sup>1</sup>I was playing around with checking MO posts for dead links. This was based on YCor's suggestion in a <a href="https://meta.mathoverflow.net/questions/4279/restoring-bill-thurstons-figures-in-an-answer#comment20489_4279">comment to another question</a>. Originally I only checked jpg files, at that time I posted <a href="https://chat.stackexchange.com/rooms/9369/conversation/archiving-images-dead-links">some details about what I triead in chat</a>. Recently, there was also a discussion about archiving externals links from posts on SE sites on Meta Stack Exchange: <a href="https://meta.stackexchange.com/q/331125">Automatically have links archived in the Wayback Machine</a>.</p>
https://meta.mathoverflow.net/q/4321-4Area 51 Mathematics Open Community ReviewsThanasis Stylianouhttps://meta.mathoverflow.net/users/406442019-08-14T15:04:28Z2019-08-19T09:41:51Z
<p>Following the discussions in</p>
<p><a href="https://meta.mathoverflow.net/q/4320/40644">Area 51 community peer review</a></p>
<p>and links therein, I have created the following proposal</p>
<p><a href="https://area51.stackexchange.com/proposals/122889/mathematics-open-community-reviews?referrer=MDA4NzFjZjJhMDcwM2U1MDRkY2ViYjljYzc2MGJhMTY3MTJiM2ViODQ0ZTBmZTgzNWQzYjQwMTlhYTQwOGVhNux_3cdc441JWegCwiwbwNlYCfkjPR8hO9HKxbuUSXhZ0">Mathematics Open Community Reviews</a></p>
<p>hoping to get things started. The proposal needs at least 5 followers within 3 days to remain alive. I would be very happy for any support.</p>
https://meta.mathoverflow.net/q/431732Catering to professional appearance a bit much?darij grinberghttps://meta.mathoverflow.net/users/25302019-08-12T18:05:58Z2019-08-31T02:45:12Z
<p><em>[In case of hurry, please scroll down to the suggestions at the very end.]</em></p>
<p>The deletion of <a href="https://mathoverflow.net/questions/1083/do-good-math-jokes-exist">the Math Jokes thread</a> (mirrors: <a href="http://www.cip.ifi.lmu.de/~grinberg/algebra/msed/mathjokes.html" rel="nofollow noreferrer">html</a> or <a href="http://www.cip.ifi.lmu.de/~grinberg/algebra/msed/mathjokes.pdf" rel="nofollow noreferrer">pdf</a>), most likely provoked by <a href="https://meta.mathoverflow.net/questions/4307/should-these-sexually-suggestive-jokes-be-kept-or-deleted?cb=1">the meta.MO debate about some specific jokes</a> but not supported by a majority of users, appears to be at least the second time that MO moderation decisions are being based on the perception of outward appearance. (The first, at least to my knowledge, was the deletion of a question about "what image epitomizes mathematics to you" after <a href="https://en.wikipedia.org/wiki/The_Scream" rel="nofollow noreferrer">this image</a> became the highest upvoted answer.)</p>
<p>There are good points to be made against having threads like this on MO; I agree with what seems to be the consensus about them, which is that these are bad questions, relics of a bygone age when MO was still figuring out what it wanted to be. The march of science would not be impeded if they had never been asked.</p>
<p>However, deleting them, in my opinion, requires better reasons than not starting them in the first place. Worse yet is my impression that the deletions are motivated not by pondering what would make MO a better forum but by an (implicit, yet rather transparent) desire to appear maximally professional, polite and smooth to the outside world. And this is not a great goal to set -- even if I assume that outside appearance is nearly as important a goal as inside usefulness (full disclosure: I don't), I believe it is too deceptive a light to steer our ship towards. Consider the likely effects of the deletion of the jokes thread: The jokes thread is no longer publicly visible. But <a href="https://meta.mathoverflow.net/questions/4307/should-these-sexually-suggestive-jokes-be-kept-or-deleted?cb=1">the question debating the appropriateness of the sexual jokes therein</a> remains visible (it's on meta, so there is far less grounds on which it could be deleted). Everyone who cannot see deleted threads is likely to conclude, on the basis of their priors and political leanings, that</p>
<ul>
<li><p>either some really creepy jokes have stood undisputed on MathOverflow since 2009,</p></li>
<li><p>or MathOverflow has succumbed to outside pressure on a current moral panic and deleted a whole thread based on a few risqué posts.</p></li>
</ul>
<p>Either of these paints MO and its governance in a worse light than the thread itself. Meanwhile, no one has stepped in to claim any actual damage from any of the deleted answers. The main forces behind the deletion seem to be "these jokes are unprofessional" and "no one cares for this thread anyway". But the slope is slippery, since we have now set an expectation that even theoretical concerns about unprofessional-looking posts will be met with deletion. Next time it may well hit closer to home, and eventually we'll <strong>have</strong> to respond with "thanks for your concerns, but our core community believes them not strong enough to delete useful content". The later this happens, the bigger the resulting shitstorm and outrage. In some circles, it is best to never become a fellow traveler, lest you become a traitor once your paths split.</p>
<p>What I've said before is not particularly novel and I expect disagreements to be at where to place our red lines rather than whether there should be any. But with too many different red lines, we'll eventually see the window of conversation narrow even further, since it is easier to get a question deleted than to get it undeleted (math.stackexchange is currently having <a href="https://math.meta.stackexchange.com/questions/30163/can-we-please-stop-closing-and-deleting-old-posts-with-answers">a similar problem</a> for other reasons). Thus, in the interest of common ground, here are some <strong>specific suggestions:</strong></p>
<ol>
<li><p>Content that appears to be useful or interesting to a reasonable number of mathematicians (witnessed, e.g., by 10 upvotes, by 5 upvotes and appreciative comments from established users, or by citations from published literature) is not to be deleted barring very grave and specific reasons (e.g., passwords being leaked).</p></li>
<li><p>Full thread deletion is to be reserved for threads with no redeeming value whatsoever. Answer deletion is to be reserved for answers that are so bad or unredeemable that downvotes and comments of disapproval don't help.</p></li>
<li><p>Vague notions like "professionalism", "appropriateness" and "inclusivity" are not to inform moderation decisions until made precise with more specific arguments. Non-CW posts are to be understood, first and foremost, as statements by their original authors, not as manifestations of the "spirit of MO" whatever it might be; they are furthermore not understood to be targeted at any specific reader unless visibly declared to be targeted. Posts should not be judged on how they would look like if ripped out of context and addressed to someone they were never written for.</p></li>
</ol>
<p>Feel free to comment and improve on these points. I regard upvotes as "I agree with the general idea and at least 2 of the 3 suggestions modulo minor issues" and downvotes as "this is going in the wrong direction". Eventually, we'll see if these concerns are worth separating and voting on.</p>
https://meta.mathoverflow.net/q/430715Should these sexually suggestive jokes be kept or deleted?Tanner Swetthttps://meta.mathoverflow.net/users/57362019-08-01T00:40:57Z2019-08-13T21:11:42Z
<p>There are a few jokes in "<a href="https://mathoverflow.net/questions/1083/do-good-math-jokes-exist">Do good math jokes exist?</a>" that I think are inappropriate.</p>
<p>Specifically:</p>
<ul>
<li><a href="https://mathoverflow.net/a/6360/5736">Nov 21 '09 at 9:01</a> item (1)</li>
<li><a href="https://mathoverflow.net/a/1229/5736">Oct 19 '09 at 16:03</a></li>
<li><a href="https://mathoverflow.net/a/8496/5736">Dec 10 '09 at 23:14</a></li>
<li><a href="https://mathoverflow.net/a/8931/5736">Dec 15 '09 at 1:31</a></li>
</ul>
<p>All of these are jokes about people's bodies (mostly women's bodies) with sexual implications. In short, this is website is a professional environment, and these jokes are inappropriate for a professional environment, so I think the jokes should be removed from this website.</p>
<p>Now, you might wonder: "Why, exactly, are these jokes inappropriate for a professional environment?" Honestly, I'm not able to explain it exactly. What I know is that in my experience, people often feel excluded by jokes like these, and when asked why, they usually provide good reasons. Hopefully someone else can explain it better than I can.</p>
<p>Besides, "sexually suggestive remarks" are explicitly against the <a href="https://meta.stackexchange.com/conduct">code of conduct</a>.</p>
<p>So, what should we do about these?</p>
<hr>
<p>I may as well mention the following jokes while I'm at it:</p>
<ul>
<li><a href="https://mathoverflow.net/a/8738/5736">Dec 13 '09 at 7:32</a> - This one uses a double entendre, albeit without any sexual implications.</li>
<li><a href="https://mathoverflow.net/a/4018/5736">Nov 4 '09 at 0:11</a> - Gross-out humor.</li>
<li><a href="https://mathoverflow.net/posts/1636/revisions">Oct 21 '09 at 11:57</a> - Toilet humor.</li>
<li><a href="https://mathoverflow.net/a/1203/5736">Oct 19 '09 at 12:04</a> - Uses sexual slang.</li>
</ul>
https://meta.mathoverflow.net/q/43067"Offline for maintenance" error message shows incorrect site namegparyanihttps://meta.mathoverflow.net/users/1202242019-07-30T17:44:35Z2019-08-16T16:26:08Z
<p>A short while ago, this site was down for maintenance.</p>
<p>However, the error page shown during said maintenance period incorrectly stated the name of this site:</p>
<blockquote>
<p><a href="https://i.stack.imgur.com/8P4dY.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/8P4dY.png" alt="Math Overflow is currently offline for maintenance"></a></p>
</blockquote>
<p>As you probably know, this site is actually called "MathOverflow". Can this please be fixed?</p>
<p>(Note that unlike the <code>/error</code> page, it's not possible to see this error page unless the site is actually down for maintenance.)</p>
<p>(Also, I cannot find any relevant tags other than the required tag for this question - can someone please add in or create the right tag?)</p>
https://meta.mathoverflow.net/q/427049What do you want to do in September for MO's tenth anniversary?Gerhard Pasemanhttps://meta.mathoverflow.net/users/34022019-06-21T17:55:22Z2019-09-27T15:28:50Z
<p>On Sep. 28, 2009, MathOverflow went online, and has almost ten years of almost constant operation, thanks to StackExchange.</p>
<p>There will be an obligatory post observing the anniversary. The board of MathOverflow LLC might hold a toast (with coffee and tea) in observance as well, and they may yet have bigger plans. Until those plans appear, this post is a staging area for people who want to celebrate the forum away from the forum (as in meeting in some locale). For a timely and well anticipated event, starting plans about now seems good.</p>
<p>How do you want to observe the anniversary? And where, and who do you want to invite?</p>
<p><strong>Edit 2019.08.28:</strong></p>
<p>Good news! StackExchange is willing to help us celebrate next month (only 31 days away)!</p>
<p>I need to know how many people plan to show up at the locations to celebrate, so I need
a head count. I also need some to volunteer as host/admins to do/delegate
what is needed to get the celebration going in your region. I will provide detail about this on Friday. </p>
<p>Right now Alec Rhea, Thomas Rot, Gerhard Paseman, Zach Teitler and
Steven Landsburg are my ideas for host/admins. If they agree, they should find my email on
my user page and contact me. Other regions will need host/admins: volunteers should also
contact me by email, as well as make a post below.</p>
<p>More information will be included Friday in my answer post below. If you have public
comments or questions, please comment on my question or answer posts.
Remember, the point is to celebrate a fine example of ten years of community action
and have fun doing it. StackExchange thanks us for being such an example, and we can thank
others during the celebration.</p>
<p><strong>End Edit 2019.08.28.</strong></p>
<p>Gerhard "Where Are All The Parties?" Paseman, 2019.06.21.</p>
https://meta.mathoverflow.net/q/425911What should I do when I see a spam post on MO?Martin Sleziakhttps://meta.mathoverflow.net/users/82502019-06-12T16:26:19Z2019-09-02T04:28:56Z
<p>What is the correct way to handle spam on MathOverflow? Can regular users do something when they see a spam post?</p>
https://meta.mathoverflow.net/q/337239Have any MO-hard problems ascended to "real" open problems in their fields?Will Sawinhttps://meta.mathoverflow.net/users/180602017-09-01T17:25:40Z2019-10-01T11:52:10Z
<p>Have any questions first proposed on Mathoverflow attracted enough interest from experts in their field that solving them would be considered a significant advance?</p>
<p>I don't want to count problems that are known (or strongly suspected) to be at least as hard as some previously described problem, unless the version original to Mathoverflow is believed by experts to be a better formulation of the problem.</p>
<p>Of course, as Mathoverflow has been around for less than 10 years, no problem original to Mathoverflow can possibly be a long-standing open problem in its field. But I don't see any reason a question asked on MO can't be among the most interesting questions asked in the last ten years.</p>
https://meta.mathoverflow.net/q/95032Who owns my MathOverflow posts?François G. Doraishttps://meta.mathoverflow.net/users/20002013-10-03T00:15:04Z2019-10-15T02:12:41Z
<p>Does Stack Exchange or MathOverflow own my posts? Can I reuse my posts elsewhere? Do I need to cite MathOverflow if I want to reuse my posts elsewhere?</p>
https://meta.mathoverflow.net/q/27717Opting out of reputationFrançois G. Doraishttps://meta.mathoverflow.net/users/20002013-06-28T23:45:41Z2019-07-29T21:03:30Z
<p>[<em>Disclaimer.</em> I'm making this feature request not because I want it nor because I think it's a good idea, but because I heard it so often that there is need to discuss it. Please don't shoot the messenger!]</p>
<p><strong>Let users opt out of reputation</strong></p>
<p>Indeed, some users have resorted to various schemes to avoid accruing reputation on MO such as answering in comments, answering in community wiki mode, discarding points through bounties, etc.</p>
<p>There are a few obvious caveats that pop to mind immediately:</p>
<ul>
<li>Since user reputation is tied to their ability to participate in the site, this option mostly makes sense after a certain minimum threshold is reached. </li>
<li>This should not stop others from voting on posts from users who have opted out since that serves other purposes.</li>
<li>Since it is undesirable to have users opt out and back in, the choice to opt out would probably have to be irreversible.</li>
</ul>
<p>Could such an opt-out work on MO?</p>
https://meta.mathoverflow.net/q/22325Requests for reopen and undelete votes for on-hold, closed, and deleted questionsAndrés E. Caicedohttps://meta.mathoverflow.net/users/60852013-06-27T05:52:17Z2019-08-18T17:56:33Z
<p>Since I expect this may prove rather useful, I'm blatantly purloining Asaf's <a href="https://math.meta.stackexchange.com/q/6424/462">question</a> from meta.math.se. </p>
<blockquote>
<p>Please post general requests for reopen votes as answers below.</p>
<p>Beware that "short" requests such as "request reopening of <<em>link</em>>" may be automatically converted to comments by the SE software, so you will need to say more, such as why you think that the question should be reopened.</p>
<p>Please do not use this thread to engage in debates on contentious matters (e.g. reasons for closure). That should be done in a separate thread - which can be linked to from here.</p>
<p>If a question is reopened then please put [REOPENED] at the start of the request (answer).</p>
</blockquote>
<p>Of course, each requested question may need some editing or other improvements before it is fit, and as indicated <a href="https://mathoverflow.net/questions/134562/set-theory-forcing#comment346706_134562">elsewhere</a>, this is desirable, and I hope may be expedited through this thread. </p>
<p>(Improvements on the phrasing are welcome.)</p>