On MO 1.0 we had, after some discussions and conflicts but still, what I think was a quite smoothly and efficiently working process of deleting "bad" content. It seems with the move to MO 2.0 this process of manual deletions came more-or-less to a halt.

Two main reasons for this could be:

  • There is now an auto-deletion script so there is less need to do so(1).

  • The deletion interface changed and makes it easy to overlook existing votes.

Are there any other reasons? Should we try to re-start manual deletions or is the situation fine anyway?

For those that might not know as 10k+ user one can vote to delete closed questions (with 20k+ one can delete certain answers). Lists of recent existing votes are available under "tools"; for example a list of pending votes over the last 30 days [10k+ only]. The list can be considerably expanded clicking the triangle; yet if the list is too long it can get cut-off, choosing a different period of time (14d, 2d, yesterday) sometimes yields different lists.

(1) The precise details of auto-deletion are somewhat involved (see "by the system" in this FAQ How does deleting work? What can cause a post to be deleted, and what does that actually mean? What are the criteria for deletion?). In brief and roughly a question will be deleted after:

  • a week when it has negative score and is closed and "unanswered".

  • a month when it has negative score and no answer.

  • a year when it has zero-score and got little attention (low-views, few comments, and no answer).

What does not get auto-deleted are questions with an answer that has positive score or is accepted. Answers with a high score typically were not deleted. What's left would be badly received questions with accepted and/or low-score answers.

Something that does get auto-deleted are questions hardly anybody took some interest in, even if there is no negative feedback whatsoever. (Only after a year, though.)

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    $\begingroup$ The motivation for this post is a recent post on Community-user deletions that raised some questions that I asked myself, too. To be clear, I am mainly curious of understand if those that used to vote to delete but do not anymore, do so because they see no need or only because they feel it is pointless as subjectively "no-one else does." $\endgroup$ – user9072 Apr 23 '15 at 12:26
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    $\begingroup$ Just as a data point, I stopped voting to delete for exactly your two reasons: because the system seems to do so automatically, and no on else seems to. $\endgroup$ – Lucia Apr 23 '15 at 13:02
  • $\begingroup$ Thanks for the data point, @Lucia // I included some remark on what gets auto-deleted and what does not get auto-deleted while it would have been deleted under the "old" system. $\endgroup$ – user9072 Apr 23 '15 at 13:20
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    $\begingroup$ My opinion is that there is altogether too much concern with closing and deleting questions. What I regret more is when an interesting question is closed, than when an uninteresting question is ignored. $\endgroup$ – Joel David Hamkins Apr 26 '15 at 20:37
  • $\begingroup$ @JoelDavidHamkins I partially agree in that I think there is an over-emphasis on closing over numerous others tasks related to community-moderation and maintenance and perhaps development of the site that would be useful to be done. By and large I also stopped doing any of them, so I better shut-up about it. $\endgroup$ – user9072 Apr 26 '15 at 21:18

I support not re-starting manual deletions. The situation today with automatic deletion and no manual deletion is better than it used to be in the manual deletions era and it is also better to avoid practicing manual deletion on top of the automatic one.

(On pupular request: update)

As quid explained: "What does not get auto-deleted are closed questions with an answer that has positive score or is accepted. Answers with a high score typically were not deleted. What's left would be badly received questions with accepted and/or low-score answers."

I think that overall, badly received questions with good answers should remain on the site. Moreover, quid described the typical situation and there were also atypical cases: there were cases were controversial questions were deleted in spite of many up-votes, or as part of an open/close dispute. Finally, manual deletion is time-consuming for users and now, with automatic deletion, for no or small marginal value.

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    $\begingroup$ Thank you for your opinion; it could be still more useful if you could add why or in which way the situation is better. $\endgroup$ – user9072 Apr 23 '15 at 18:20
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    $\begingroup$ I agree with Gil that "automatic deletion and no manual deletion is better than it used to be in the manual deletions era". I do not see why "it is also better to avoid practicing manual deletion on top of the automatic one". Why is this so, Gil? The only reason I can see is that, as a responsible 10K user, I should think about voting to delete a bad post if I have that "power". Fortunately, I am not that responsible, so it does not bother me. You, on the other hand, are very responsible and approaching 10K "status", so maybe it bothers you... $\endgroup$ – Bill Johnson Apr 24 '15 at 0:34
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    $\begingroup$ @Bill, I believe that Gil has been over 10K and back several times, on account of bounties that he has given on his own and other's questions. $\endgroup$ – Joel David Hamkins Apr 24 '15 at 13:12
  • $\begingroup$ @JoelDavidHamkins This is true (and the rep-recalc also plays a role in him being below 10k+ at the moment). However, it seems to me, this is a quite tangential aspect of Bill Johnson's remark. $\endgroup$ – user9072 Apr 24 '15 at 13:36
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    $\begingroup$ Thank you for taking the time to elaborate, I agree that the current situation has the advantage of avoiding some conflicts, which while more rare in later days still occured sometimes. It is also true that not doing manual deletions saves some time (although one could still benefit from auto-del and only consider questions past the first, or second, auto-del time for manual deletion). However, I also think that some questions do not get deleted that should better be deleted, in that sense I cannot agree fully that there would be "no good purpose;" yet the benefit might indeed be (too?) small. $\endgroup$ – user9072 Apr 24 '15 at 13:47
  • $\begingroup$ Anyway, the question was neutral and curiosity-motivated so if somebody supports a policy that we should restart manual deletions, I suppose that he should advocate this position in a separate answer. $\endgroup$ – Gil Kalai Apr 24 '15 at 15:28
  • $\begingroup$ Indeed, as the questions was neutral there seems little need for slightly loaded language like "waste of time" and "no good purpose." (Personally, I am actually not sure what is the best way to proceed. However, I sense that you do not wish to further dicuss the subject so thanks again for your opinion.) $\endgroup$ – user9072 Apr 24 '15 at 16:05
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    $\begingroup$ I don’t think this is a question of policy. The infrastructure is there, and it’s not as if we can force anyone to actively use it. As far as I can tell, “restart manual deletions” just means “bring the problem to light to encourage people do it more”. $\endgroup$ – Emil Jeřábek Apr 24 '15 at 17:52
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    $\begingroup$ Dear Emil, It is a policy question: do we want to "encourage people to do it more" or do we want "not to encourage people to do it more". Dear quid, I formulated now my position as mallow as I can. Generally speaking, perhaps unlike Bill, I regard the responsible approach of a professional academics to be "to avoid as much as possible getting involved in non-crucial administrative jobs." And making a second round (after the automatic system) of decisions if a closed MO question is 6-rate (so it should be left closed) or 7-rate (so it should be deleted) is not crucial to say the least. $\endgroup$ – Gil Kalai Apr 25 '15 at 17:28
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    $\begingroup$ In addition, administrative decisions of this kind (as other decisions) can occasionally deteriorate into small struggles. Another general point which applies to deleting problems as to other more important matters (and it is difficult to think about less important matters) is that there is a tension between "cleanliness" and "tolerance" and I don't see why it is necessary to make sure that MO is cleaned from all bad question. $\endgroup$ – Gil Kalai Apr 25 '15 at 17:37
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    $\begingroup$ Thank you for the reformulation. A point you seem to put aside, though this should be largely my fault as I did not stress it in the question, is that the manual process included manual/human oversight over what does get deleted (and maybe should not). Trying to be a professional academic, I should better finish something else first. But I will try to give some example of what I mean later. $\endgroup$ – user9072 Apr 25 '15 at 18:19

The title of the question mentions manual deletions, and Gil Kalai's answer voices his opposition to that. Let me answer quid's other concern: the system is currently automatically deleting some perfectly fine questions. I encourage 10k+ users to monitor the list of recently deleted questions, and vote to undelete reasonable questions that have slipped through. This is not a huge problem, only five or six questions in the last week have been undeleted (I think I voted on three or four of these), but it would seem good for people to look at the automatic deletions from time to time.

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    $\begingroup$ Just a practical remark: after undeleting such posts it can be useful to try to make sure that the post stops fulfilling the auto-delete criteria (often an up-vote suffices). If not they will just be deleted again after a few days. $\endgroup$ – user9072 May 1 '15 at 16:21
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    $\begingroup$ @quid: That's a good point. And one more practical note -- those who wish to look at the deleted posts can quickly skim for posts that were not closed but yet deleted. This is quite rapid, and I am inclined on principle to vote to undelete any such question. $\endgroup$ – Lucia May 1 '15 at 16:24
  • $\begingroup$ "the list of recently deleted questions": How does one access this list? $\endgroup$ – Joseph O'Rourke May 2 '15 at 12:26
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    $\begingroup$ @JosephO'Rourke: From the main site click the 'review' link on the toolbar, and then click the 'Tools' link. From there check in the 'delete' tab, and you can see both the questions which people have voted recently to undelete (and those that were undeleted), and also the questions that have been recently deleted. $\endgroup$ – Lucia May 2 '15 at 15:29

Guess the deleted question!

Q1: I need following books (soft copies)

I know this is not the place to ask for such help, but I cant find these books in my country and not even on line and the shipping is very expensive. If someone out there have any of these books (soft copies), please email me.

A) A. H. Zemanian, "Generalized Integral Transforms", Intersciene, New York, 1968. B) A. H. Zemanian, "Distribution Theory and Transform Analysis", McGraw-Hill, New York, 1965.

Q2: Time decay for Hartree equation with Coulomb potential

Are there any time-decay results for the solution of the Hartree equation \begin{equation}\frac{1}{i}\partial_t\phi-\Delta\phi=-(|x|^{-1}\ast|\phi|^2)\phi,\quad x\in\mathbb{R}^3\end{equation} in $L^p$-spaces which would ensure e.g. $\phi\in L^2((0,\infty);L^3(\mathbb{R}^3))$ or $\phi\in L^2((0,\infty);L^4(\mathbb{R}^3))$?

According to the information at DispersiveWiki, Coulomb potential is the borderline case and there is no scattering results (in the sense of asymptotic compeleteness) (??) for the solutions of the above equation. There is a paper by Hayashi and Ozawa on time-decay for Hartree equation with Coulomb or more singular potentials which makes use of pseudo-conformal invariance. This work implies that one can get rates like $\|\phi\|_4\lesssim t^{-3/8}$ or $\|\phi\|_3\lesssim t^{-1/4}$ where $\phi$ is the solution of the above equation. Those are slower rates compared to the rates at which free solution decays. Is there more recent publication which might imply better rates? Do you know of any $L^\infty$-decay results (for the above equation) which might be interpolated by mass conservation to get faster $L^p$-decay?

Hints: Both were asked about a year ago. The first is closed and has score -5. The second is open and has score 0.

Since I ask, one might still have easily guessed that Q2 was the (auto-)deleted one, while Q1 would not get (auto-)deleted [under current rules and in current form]. (Comment: following this post, this got fixed by manual votes.)

Why? Well, because Q1 has an answer that reads:

both books can be traced on amazon. there are rather cheap used copies available.

Somehow it got score 2, and that's it as regards auto-delete. (While in my opinion more likely than not it does not answer the question at all, as it is made clear that the shipping costs are the issue.)

Now, let me stop my attempts at humor.

I think by and large auto-delete works alright or essentially "good enough" and there is no reason for major activity or concern.

However, as the above examples show, I think, the situation is not perfect, either. This is also not a unique example; likely one could produce hundreds, but then "hundreds" are only around one percent so it is not that big a deal either. Still, a little manual fine-tuning here and there might not be entirely useless.

Now, somebody might wonder why I did not do anything about the above questions. Well, I did cast my votes. Somebody else did, too. But, we'd need a third vote, and none was coming... (until I wrote this post, see comments below).

The undeletion and deletion process seems for (almost) all practical purposes simply broken. If too few check (and to be sure, I have to confess I do not check often either), undeletions and deletions just cannot happen anymore. This is likely not a tragedy, but it seems not good, either.

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    $\begingroup$ I apologize in case the authors' of the quoted posts should be unhappy with them being used as examples (I do not link or give names on purpose). This goes especially for Q1. Let me stress it was a "first question" and I do not see much problem with it being asked, and perhaps even answered, but maybe we do not need to keep it forever. $\endgroup$ – user9072 Apr 25 '15 at 22:37
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    $\begingroup$ Good example. I cast the third vote to undelete. $\endgroup$ – Lucia Apr 25 '15 at 23:20
  • $\begingroup$ Maybe it's worth exploring if the auto delete criteria can be adjusted a bit? E.g. by not deleting any question that has no downvotes, even if it hasn't attracted interest yet. Or alternatively, to make sure that the deletion protocol becomes widely known so that people vote questions up a little more generously than seems currently to be the case. $\endgroup$ – Lucia Apr 25 '15 at 23:24
  • $\begingroup$ Thanks for the vote @Lucia. On the script: I agree that it might make sense to see if something can be done to adapt the 365-days script. I think it is not well-tuned for highly specialized mid-sized sites such as MO. For the large ones it seems necessary and for the small ones it will rarely cause an issue, but in the middle it is not so great. (I will check if I find earlier discussions on Meta Stack Exchange) $\endgroup$ – user9072 Apr 25 '15 at 23:39
  • $\begingroup$ Thanks for the examples, Quid. Can you add links to the two questions? Certainly Q2 should be undeleted. Was it closed? Can it be automatically deleted without being closed earlier? Certainly, when questions are closed by mistake and then deleted I support undeleteing and unclosing them. In any case the automatic deletion should NOT apply to open questions. $\endgroup$ – Gil Kalai Apr 26 '15 at 4:45
  • $\begingroup$ @GilKalai Details of automatic deletion can be found here. It is very rare for postively-scored questions to be automatically deleted, though there are circumstances where open but non-positively-scored questions can be deleted. For negatively-scored, unanswered questions it can happen after 30 days. For zero-scored (or 1-scored if the owner is deleted), unanswered (and essentially "forgotten") questions it can only happen after 365 days. So if you see a question that you think should remain on the site, upvote it. $\endgroup$ – user642796 Apr 26 '15 at 7:17
  • $\begingroup$ @GilKalai I explained why I did not really want to link, but the situation now is reversed anyway as my post got the votes (see earlier comments): but here are the links Q1 [10k+] and Q2 No, Q2 was not closed, in fact this was mentioned in my hint. I added some more details on auto-del in my post (the summary I gave was not so good) in addition to the link I had given, explaining the rules. Open question do get deleted, even open question that were never down-voted. $\endgroup$ – user9072 Apr 26 '15 at 8:29
  • $\begingroup$ In case that somebody notice an unjustified automatic deletion I suppose he can post a request to undelete as an answer to "Requests for reopen votes". Other than that, as I said, I see no reasons now for manual deletions. $\endgroup$ – Gil Kalai Apr 26 '15 at 16:24
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    $\begingroup$ @GilKalai very well. Only, for somebody to notice, somebody has to look through the lists on the deletion page (else one hardly will notice). Whether or not users should feel some motivation to do this is a main point of the discussion. On the other point: you might not know, but there is a dedicated list of undelete votes cast, to manually repost the votes would simply duplicate something that exists and is automatically updated. Better let us not invent a 2nd layer of bureaucracy. (Also, questions like the one above getting deleted is rather frequent.) $\endgroup$ – user9072 Apr 26 '15 at 17:40

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