It seems that Qing Liu decided to leave MSE. Know anyone why he did this? (He was QiL, QiL'8, and lately user18119. )

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    $\begingroup$ Qing Liu is a world renowned algebraic geometer and has written one of the best books of the last quarter of century on his subject. He was second to none on this site for questions tagged algebraic geometry and always answered in an extremely erudite, didactic and friendly way. I consider his departure as a catastrophe for this site. $\endgroup$ Sep 11, 2013 at 22:19
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    $\begingroup$ @GeorgesElencwajg I just flagged your comment mentioning the " moderators should read it for their own benefit ". This is sad. $\endgroup$ Sep 11, 2013 at 23:45
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    $\begingroup$ I left my mind reading cap in my other pants back in Israel, so I can't say why Qing Liu deleted his account. I don't think moderators can or should divulge such information when a user is deleted, moreover community managers handle deletions. Try emailing him. $\endgroup$
    – Asaf Karagila Mod
    Sep 11, 2013 at 23:45
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    $\begingroup$ @YACP Regular moderators can't delete very high-rep users anymore, so this self-deletion request was likely handled by an SE employee. There is a deletion reason that is filled out by the deleting user, but even if that one would contain more details, which is unlikely, I'm not sure if mods would be allowed to share that information, or if it falls under the moderator agreement. $\endgroup$
    – user9733
    Sep 12, 2013 at 5:40
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    $\begingroup$ I totally agree with YACP. Community needs to know why such a prolific contributor has left the website. Maybe it is something that we, as a community, did to make Qing Liu leave MSE. Of course, the reason why he left will be probably unique, and obviously subjective, but I find it somewhat shocking that he asked for permanent deletion, as if user18119 wasn't anonymous enough. Writing an email to him would be a nice way to go (especially for those who personally know him), and if anybody does email him, please consider posting his reply here (of course, with his permission). $\endgroup$
    – Prism
    Sep 12, 2013 at 7:54
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    $\begingroup$ Wow, I just want to comment that I have always been in awe of QiL'8. I just thought he was a remarkably talented student, I had no idea he was Qing Liu! This is very upsetting to learn that we HAD such a fantastic author, as well as question-answerer on our site. $\endgroup$ Sep 12, 2013 at 8:07
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    $\begingroup$ I've never even noticed the man, but with all the drama I wanna know too! $\endgroup$
    – Git Gud
    Sep 12, 2013 at 8:23
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    $\begingroup$ Let me agree with those above who are lamenting the department of this user, who was among the highest-quality contributors to algebraic geometry questions on this site. But let me also agree with those who think that if he chose not to share his reasons for leaving, it's not anyone else's business to try to discover them. $\endgroup$
    – user64687
    Sep 12, 2013 at 14:00
  • $\begingroup$ Maybe he would like to be anonymous? $\endgroup$
    – copper.hat
    Sep 12, 2013 at 23:00
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    $\begingroup$ @Prism, I think it is rather the case that his reasons are not unique at all, they are connected to the inability to delete answers (after 30 days, say). $\endgroup$
    – zyx
    Sep 13, 2013 at 21:54
  • $\begingroup$ @zyx Are you sure? I'm convinced that I can delete any post of mine, no matter when it was posted. $\endgroup$
    – user26857
    Sep 13, 2013 at 21:57
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    $\begingroup$ @YACP, I mean that other users, or moderators, can decide to reverse your deletion at any time. There is no hard deletion after the 30 day visibility period when it is listed under "Recently Deleted". $\endgroup$
    – zyx
    Sep 13, 2013 at 22:01
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    $\begingroup$ I think there should be seriously looked into though what incentives to leave the many recent departures of key members might have in common. $\endgroup$
    – dreamer
    Sep 14, 2013 at 9:02
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    $\begingroup$ @rbm Well, most of the comments here show that the community is not worried about this. $\endgroup$
    – user26857
    Sep 14, 2013 at 9:06

2 Answers 2


Qing Liu decided to leave for reasons that he has apparently chosen to keep private, taking care to make as little noise as possible in his departure.

I think that we should respect that by not prying into what is clearly a personal decision.

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    $\begingroup$ Thank you. While I understand the curiosity, I don’t see that it’s any of our business. $\endgroup$ Sep 12, 2013 at 9:45
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    $\begingroup$ We emphatically do not have any right to know. It might be something we really want to know, but I'm afraid that's quite a different thing. $\endgroup$ Sep 12, 2013 at 18:31
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    $\begingroup$ One should be careful with asserting other people's privacy interests in such cases. A number of people appear to leave out of dissatisfaction with the way SE operates and with no evidence of any desire for privacy. Requests to "not read [departing user's] mind" can serve as a gesture of respect but if made without any reference to the facts of the case they can also (intentionally or not) serve as a reflexive defense of the status quo. $\endgroup$
    – zyx
    Sep 12, 2013 at 23:20

Some of the the reasons appear to be public, and there is no reason to believe anything about the user wanting privacy or not. He happens to have not stated the reasons, but people requesting deletion rarely have any reason to open a meta thread explaining things. The only case that comes to mind is one user who staged a public protest (it was phony but successful; he opened a new account). I do not remember anybody saying goodbye except in user profiles that did not belong to deleted accounts.

At the time of the previous meta thread about this deletion, it was still possible to check the user's recent comment history. A few days before the deletion he had tried to remove an answer after commenting that it was no longer relevant to the question. This was denied for some SE reason, and after surprise was expressed about this (along the lines, "what? you mean it is not my answer to delete?") a moderator commented with an explanation of Creative Commons licenses and such. The deletion request came soon after that.

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    $\begingroup$ That is, I consider this a relevant case for the recent discussion of whether the inability to hard-delete answers (making them visible only to mod/dev privileged accounts) is a reasonable policy. $\endgroup$
    – zyx
    Sep 12, 2013 at 23:24
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    $\begingroup$ My interpretation is that this user would have stayed, and might still agree to have his account restored (reversing the deletion), if he knew that he had sufficient ability to remove his own answers. This is a general SE problem. I consider the recommendation to not discuss this case out of privacy as (intentionally or not) effectively a way of hijacking the situation to protect the very thing that the user expressed unhappiness about, and it is strange to determine for him that he would be happy with such "respect". $\endgroup$
    – zyx
    Sep 13, 2013 at 21:46
  • $\begingroup$ @YACP: Are you claiming that the community moderators are turning away users, or the SE moderators? I agree that the SE team has a history of it (particularly Jeff Atwood, who has since left SE), but the community moderators don't in any way. $\endgroup$ Sep 15, 2013 at 0:27
  • $\begingroup$ (Note that "if he knew he had sufficient ability to remove" means "if SE software were to change, or he had an assurance from moderators, that his decisions on deletion of his answers would not be reversed". The problem is that deletions are very much outside of users' own control, and no hard-delete exists, not that these facts are insufficiently advertised.) $\endgroup$
    – zyx
    Sep 15, 2013 at 1:02
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    $\begingroup$ @YACP: There are the moderators of math.SE, elected by the community; and there are employees of the Stack Exchange company, who have moderator powers on every site. It's unfortunate that you didn't run in any elections, comment on any nominations, or post in any of the election meta threads if you think the math.SE moderators are so inept or malicious that they turn away valuable users left and right with their actions. I think you should open a meta thread with a detailed account of this trend you claim to see, so that the community is aware of how the moderators are doing. $\endgroup$ Sep 15, 2013 at 1:13
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    $\begingroup$ Just dropping hints in the comments here with "I have enough examples" and "far from the first case" doesn't help anything. $\endgroup$ Sep 15, 2013 at 1:14
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    $\begingroup$ @YACP: With one exception, in my $2+$ years here I’ve seen no sign of MSE moderators targeting individuals, let alone ‘high rated users’, and the exception involved moderators in effect targeting each other. I’ve had fairly sharp disagreements with one or two former moderators, but they were no different in kind or in effect from a few disagreements that I’ve had with non-moderators. The current crop are a pretty diplomatic bunch. I really doubt that you can support your allegations. $\endgroup$ Sep 15, 2013 at 9:08