With any online community, as the users and the company owning the domain change, it is inevitable that some users will want to exit the community. For example, many Facebook users deleted their profiles after the 2020 presidential election in the USA, and this also deleted their data from Facebook’s servers. However, on MathOverflow, deleting your profile leaves most of your data on the site. Your name will be removed and your profile renamed to something like user12345, but your questions, answers, and comments remain. Also, comments of others like "As David White wrote above, ..." remain unchanged, so it’s easy to realize that user12345 was David White, and to also gather all contributions by that user.

It is easy to imagine hypothetical scenarios (hopefully all extremely unlikely) that would cause a user to no longer want to be publicly affiliated with MathOverflow, e.g.,

  1. The company decides to monetize it, so all users have to pay to use the site (this happened with CouchSurfing, for example).
  2. Something terrible happens with the company, so that you as a professional mathematician no longer want to be associated with them (something like this happened with DataCamp).
  3. The nature of the community changes radically, e.g., MathOverflow becomes Chegg and everyone comes here to get their homework answered, and again you don’t want to be associated because you don’t agree with the shift.
  4. The community changes and becomes known as a nasty place, perhaps one that contributes to the problem of the underrepresentation of women and minorities in mathematics.
  5. The political landscape in your country changes, and now you're worried about government prosecution for an opinion you once shared on the site.
  6. etc.

I know it’s not popular to think about these kinds of worst-case scenarios, but I do think it’s valuable, especially because the help documents essentially say "any data you put here belongs to you but is licensed to the SE company forever" and tells you that deleting your profile doesn’t remove your data. While we all hope the community agreements and standards hold forever, and make the scenarios above impossible, it’s a sad fact of life that throughout history companies have broken promises to users, or changed in fundamental ways, which would necessitate this kind of exit.

Even if you think none of those scenarios is likely, it’s worth thinking about what will happen to the data you’ve entered on the site, after you die.

If user X wanted to scrub their presence from the site, before deleting their profile, that user could delete every question, answer, and comment they’ve ever posted. Of course, high rep users could still see the deleted questions and answers, but user X could also edit the text down to just a single character, to make it harder to uncover what was there. However, this kind of thing was once called "self vandalism" by a MathOverflow moderator, making me wonder about the question of who really owns contributions. Furthermore, this procedure would take a long time, and it strikes me that moderators have the power to fully delete content (I think it's called "destroying an account"), e.g. as happens with spam answers. Hence my questions:

(1) How could one automate a complete or maximally-possible removal of one’s data from MathOverflow?

(2) Is there interest in the community in having the ability to ask moderators to destroy our accounts, for the reasons explained above.

Please don't answer along the lines "According to the terms of service of the site, the following will happen when a user deletes their account..." or "Hey, every user agreed to the terms of service, so it's wrong that they would want to remove their contributions years later." It's worth pointing out that the procedures around deletion and contributions have changed since many users started using the site, and several of the hypothetical scenarios above are changes that a user might not have been able to forecast when they started using the site 10+ years ago. Rather than answers like "this cannot be done; we own all user contributions forever" I am interested in actual solutions, or in understanding if there is interest in the community in having the ability to request that moderators destroy an account at the request of the user, which would have the effect of deleting all contributions. I would also like to say that I myself am not currently considering deleting anything from mathoverflow, but events over the past year (e.g., the moderator strike, parent company changing policies without input from users, etc.) led me to wonder about how long-time users can exit the community, based on hypothetical scenarios.

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    $\begingroup$ Is it true that in the European Union there is a "right to be forgotten" procedure to follow to get references to you removed from social media? (As a non-European, I only vaguely remember this, and do not know the details.) $\endgroup$ Commented Jan 3 at 17:21
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    $\begingroup$ Since you "wonder about the question of who really owns contributions", I'll point out this faq post on this meta: Who owns my MathOverflow posts? $\endgroup$ Commented Jan 3 at 21:50
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    $\begingroup$ Sorry, I overlooked that. (Unless I missed something, you haven't included those links in your post. ) Unrelated to this, I will add that this part seems a bit imprecise: "that user could delete every question, answer, and comment they’ve ever posted". The software does not allow self-deleting questions and answers in many cases. (Questions: If there is an upvoted answer or at least two answers. Answer: If the answer is accepted. I hope I remember this correctly.) $\endgroup$ Commented Jan 3 at 22:34
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    $\begingroup$ Since you mentioned my name, let me point out that "self-vandalism" isn't my concept. It's considered a violation across the SE network, and SE policy has always been to revert such actions. "Please do not vandalize your posts. By posting on the Stack Exchange network, you've granted a non-revocable right for SE to distribute that content (under the CC BY-SA 3.0 license). By SE policy, any vandalism will be reverted." $\endgroup$
    – Todd Trimble Mod
    Commented Jan 4 at 3:17
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    $\begingroup$ @ToddTrimble Probably it is worth mentioning that the posts with negative score are deleted in such case. And that the mods have an option to delete an account together with all posts - but the later option is probably used rarely and reserved mainly for spammers. At least if the information here is not outdated: Does deleting an account delete the associated posts and comments? It seems that this is actually called destroying a user: What is the difference between a deleted user and a "destroyed" user? $\endgroup$ Commented Jan 4 at 5:06
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    $\begingroup$ Suppose someone went to a university library and grabbed a hard copy of a journal with a paper they wrote in it, and because of the publisher being bought out by a dodgy outfit they didn't like, ripped their paper out of the journal so they were not longer associated with the publication — it would be called vandalism. If one instead paid a hacker to delete one's article from off the publisher's website and entire database as well, that would be vandalism. Our answers here are donated to the community, and aren't wholly our own. Doesn't answer your question, but puts context around "vandalism" $\endgroup$
    – David Roberts Mod
    Commented Jan 4 at 7:30
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    $\begingroup$ A scenario which might be even worse than the ones you mention, would be one where for some moral reasons the future dominant community of MO would impose changes on old posts. E.g., "It was proved by Euler" would be considered in 2040 as offending and replaced with "It was proved by Her Majesty Euler" and corrected accordingly on then-old posts. (This one is deliberately ridiculous, but I have more polemical and plausible similar ones in mind, which I'll refrain from mentioning.) $\endgroup$
    – YCor
    Commented Jan 4 at 10:46
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    $\begingroup$ Since the question linked in the previous comment by @DavidWhite is deleted at the moment, here is a Wayback Machine snapshot: Unethical requests from the senior professors and chair. $\endgroup$ Commented Jan 5 at 4:08
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    $\begingroup$ The idea that a user could decide to remove all their posts and the site has to comply is thoroughly incompatible with the letter and spirit of the CC-BY-SA licence. If you want to retain full control of the fate of content you create, there is no solution other than not publishing it under a licence that warrants free distribution of the content. $\endgroup$ Commented Jan 5 at 6:52
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    $\begingroup$ @DavidWhite I used non diamond powers to repair vandalism and then used diamond powers to temporarily lock the post while the content dispute was resolved. I suggested two courses of action that I thought were suitable since the post did not contain any identifying information and was from a throw away account. OP never followed up explaining why those suggestions where insufficient or asking for a different moderator to step in. Had they, a different conclusion could have been reached. $\endgroup$
    – StrongBad
    Commented Jan 5 at 14:19
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    $\begingroup$ I interpret the downvotes instead to reflect the view that some people don't think it should be possible for a user to delete content in the way you are seeking. $\endgroup$ Commented Jan 5 at 17:19
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    $\begingroup$ @DavidWhite You have remarked several times about possible bad behavior by SE, and so I wonder whether you are aware of the special legal nature of MO with respect to SE, explained here: meta.mathoverflow.net/a/970/1946. The long and short is that we as a community can decide to bring the entire MO site outside of SE if we should wish, and this might address some of your concerns. $\endgroup$ Commented Jan 5 at 18:02
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    $\begingroup$ @DavidWhite Instead of "mass deletion," maybe the title should say "complete" or "total" deletion? When I first saw the word "mass," I thought it meant the deletion of the content of a huge number of users all at once. But I think you're referring to deleting the content of a single user, with the emphasis being on complete extirpation of all records, rather than the volume of deletions? $\endgroup$ Commented Jan 5 at 18:38
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    $\begingroup$ "Even if you think none of those scenarios is likely, it’s worth thinking about what will happen to the data you’ve entered on the site, after you die." And why on Earth would I care about that??? I have injected certain amount of good and evil into this world, and when I leave, it will be entirely its problem how to digest it or how to spit out. Mostly it is its problem even when I'm still alive. $\endgroup$
    – fedja
    Commented Jan 5 at 21:09
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    $\begingroup$ @MartinSleziak I think David White's concern is that sometimes the identity of someone can be inferred even if the name is deleted. He mentions this at the end of his first paragraph. $\endgroup$ Commented Jan 6 at 2:42

1 Answer 1


This is a community-wiki summary of some of the comments.

First, a few preliminary clarifications. The MathOverflow corporation is completely independent from Stack Exchange so we should not to conflate the two. Users own their content, but by posting, they release their content under the terms of the CC BY-SA 4.0 license. This means that the MathOverflow corporation is under no obligation to comply with a request from a user to eradicate all traces of the content formerly provided by the user. To introduce such an obligation would require a major change in the license agreement, which is not a realistic possibility.

Moderators can destroy a user, which means that the user's content will be deleted; however, deletion is not the same as complete extirpation, since deleted posts remain visible to users with sufficiently high reputation. Therefore, even if the moderators agreed to institute a policy (or even an automatic process) to honor requests for destruction, David White's "worst-case scenarios" involving severe human rights abuses would still not be addressed.

An imperfect but possibly useful analogy is an open-source mathematical journal. Most people would regard attempts to destroy journal articles as an act of vandalism, even if someone was destroying their own articles. Stack Exchange similarly has a concept of self-vandalism.

  • $\begingroup$ Good point about the title. I've updated it, to try to make it clearer what the question is about. Also, it's worth pointing out that, because of the periodic data dumps, even if a user is "destroyed" there is an easily accessible record of their past contributions, which is worth bearing in mind for anyone concerned about the "worst case scenario" meta.stackexchange.com/questions/315378/… $\endgroup$ Commented Jan 5 at 20:53

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