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This is a non-technical question, but certainly relevant for the TCS community. If considered inappropriate, feel free to close.

The Complexity Zoo webpage (http://qwiki.stanford.edu/index.php/Complexity_Zoo) has certainly been of great service to the TCS community over the years. Apparently it is down since quite a while. I was wondering, if someone is still maintaining it, if it has moved, if there is a backup server, or if there are other plans to preserve this wonderful database of complexity classes, their relationships and citations to relevant publications. If not, are there comparable webpages that could be used as a replacement?

UPDATE (Aug 1, 2012): The Zoo is back online, and Scott is looking for people volunteering to mirror it to avoid any future outages.

Emil Jeřábek
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Martin Schwarz
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    Please do not abuse cstheory.stackexchange.com as a place for announcements and discussions. Thanks. – Tsuyoshi Ito Jul 25 '12 at 13:21
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    Have you tried to email any of the zookeepers? – Alessandro Cosentino Jul 25 '12 at 13:29
  • @AlessandroCosentino: yes, Chris Granade did respond to me. He was only involved in maintaining part of the content, but not at all with running the server. – Martin Schwarz Jul 25 '12 at 13:32
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    @TsuyoshiIto: I see the concern, but I think asking the relevant community about preserving a relevant community resource is not inappropriate. Anyway, I will certaintly accept a ballot to close the question. – Martin Schwarz Jul 25 '12 at 13:36
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    A question (and warning sign to the community) about the status of a valuable resource seems strictly more pertinent a question to the study of theoretical computer science as one about Alan Turing documentaries or Funny TCS-related papers etc. Of course, at such a time as the Zoo is found to be in good working shape, it would also be appropriate to flag the question as "too localized". – Niel de Beaudrap Jul 25 '12 at 14:50
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    @Niel: Existence of those questions has nothing to do with whether this question is in scope. – Tsuyoshi Ito Jul 25 '12 at 14:52
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    @TsuyoshiIto: that is true; I'm just demonstrating lower bounds which the community seems happy to accept (including those with moderator power, inasmuch as those questions are still open), supplemented with the argument that we should expect those lower bounds to be very loose indeed. – Niel de Beaudrap Jul 25 '12 at 14:53
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    Where is your question? “Is the Complexity Zoo dead?” is not a question. And it is sad to see that this non-question receives 9 up-votes just in two hours whereas much real questions receive much less attention. This shows one of the worst aspects of cstheory.stackexchange.com. – Tsuyoshi Ito Jul 25 '12 at 14:53
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    By the way, I am not doubting that you posted this non-question in good faith, although it is an inappropriate use of this website. – Tsuyoshi Ito Jul 25 '12 at 14:59
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    @TsuyoshiIto: I thought that "I was wondering, if someone is still maintaining it, if it has moved, or if there are other plans to preserve this wonderful database of complexity classes, their relationships and citations to relevant publications" was enough of a question to me to surpass mere alarmism. (And it is technically answerable: for instance, there exists a PDF version of the state of the Zoo at some point in time.) -- As for the popularity of this and other "soft" questions relative to others: maybe accessibility is the problem? – Niel de Beaudrap Jul 25 '12 at 15:05
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    think that the use of comments to argue whether a question is ontopic or not is not a good use of stackexchange yet it constantly happens here in the TCS stackexchange. it seems the community here is a little overzealous as gatekeepers compared to other stackexchanges. its basically a meta issue. just use the other mechanisms-- voting, closing questions in extreme cases, the meta section. – vzn Jul 25 '12 at 18:03
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    @vzn is exactly on the money: this discussion is for meta – Sasho Nikolov Jul 25 '12 at 20:04
  • a discussion at meta.mathoverflow (which is similar in spirit to cstheory.se more so than other se sites) concluded that a somewhat similar question is not appropriate there http://goo.gl/Xw58f. but our question has more hope for an objective answer – Sasho Nikolov Jul 25 '12 at 20:12
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    @Martin, I am also sad that it is down but I agree with Tsuyoshi. Administrative questions about the Zoo should be sent directly to the people managing it (Scott, Greg, ...). I think a more reasonable question would be to ask for a backup version or a similar site that can be used as a replacement while the Zoo is down. I would suggest that you edit the post in that direction. – Kaveh Jul 25 '12 at 20:26
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    There's also a snapshot of the site here (as of July 20, 2011). – arnab Jul 25 '12 at 20:54
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    @Kaveh: I've updated the question as recommended. – Martin Schwarz Jul 25 '12 at 21:06
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    I know that I'm a little late to the party here, but to be completely honest, questions like this keep me coming back here. We're a community, and this is relevant to me. Besides, it's a soft question. Without soft questions this site can be really dry. – Josephine Moeller Jul 26 '12 at 04:38
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    clarification-- seems like comments in the form "this is not TCS" are not helpful. (just downvote it only for equivalent or better effect.) comments in the form "this is not TCS & downvoted this because [xxx]" are somewhat more helpful. comments in the form "this is not TCS but it would be if it were adj'd/rephrased as [yyy] (and would upvote it in that case)" are probably most helpful/constructive. ps the Complexity Zoo is one of the more high profile TCS resources for the public, is referred to all over this stackexchange & defn deserves significant attn/care from the TCS community. – vzn Jul 26 '12 at 14:43
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    @arnab: That should be an answer, and quite possibly should be the accepted answer. – Niel de Beaudrap Jul 27 '12 at 22:59

3 Answers3

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I cannot remark on whether the Zoo has a continuous existence on the web or elsewhere. However, there are still some proto-Zoo and Zoo-derived resources available on the web.

Other sources on the net seem to be links to the first (or to the URL to the stanford.edu subsite), or pieces of the second.

It is worth noting that the entire qwiki.stanford.edu subsite seems to have disappeared, and that google searches for "qwiki", with or without specifying "stanford", either yields references to a multimedia product launched in January of last year, or produces the typical spoor of SEO companies trying to leach off of online resources.

Niel de Beaudrap
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Scott Aaronson just reported that the Complexity Zoo is down because the graduate student that was hosting it has graduated.

To get the Complexity Zoo working again, we need someone to host and a copy of the site.

Tyson Williams
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Now that the site is again up and running, I guess anyone can download most (?) of the data (machine-readable source code, with full edit history) as follows:

  • Go to http://qwiki.stanford.edu/index.php/Special:Export
  • Enter Computational Complexity in the field "Add pages from category", click "Add" — double-check that all relevant pages are now listed in the text box
  • Un-check "Include only the current revision"
  • Click "Export"

It produces a fairly large file, approx. 160 MB.

Jukka Suomela
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