I know that the Stack Overflow in Russian and Russian Language (in Russian) sites were imported from hashcode.ru, a Russian-language clone of Stack Exchange. Given that the company's website http://sezn.ru/ redirects to Stack Overflow in Russian and based on what's been said here on meta, it appears that SE has acquired that company.

However, I noticed that there are currently two sites, a Math site (http://math.hashcode.ru/) and a Physics site (http://phys.sezn.ru/), that have not been imported.

Are there plans on importing those sites, or will they be run as separate sites? Is SE involved in running those sites? What's to become of them?

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    MSDN.WhiteKnight highlighted the situation very well. Could you please tell me if you still have any questions? Oct 10, 2018 at 13:29
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    @NicolasChabanovsky It lacks discussion on the Physics site, plus it does not conclusively refer to what the future plans are (it just has speculation). Also, why was the decision made to import the Russian (in Russian) site to Stack Exchange 2.0, instead of all three former non-SO sites being hosted like the Math and Physics sites? It would be best if there were an official answer that confirmed the community answer. Oct 10, 2018 at 13:34

2 Answers 2


MSDN.WhiteKnight highlighted the situation very well. Just a few extra notes:

What sites did we import?

It was a two-step decision.

  1. Evaluation of a site. SE employees went through each site and checked how much content complies with the SE rules (e.g. plain homework questions aren't allowed).
  2. Discussion with the community. After the evaluation, I contacted a community or its top users and asked them what they want: either delete the portions of the site that do not meet the SE rules and migrate to the SE 2.0 platform, or leave it as is.

As a result, the Russian Language site was imported, and the Mathematics site wasn't. As I said and MSDN.WhiteKnight quoted:

Mathematics users did not agree to throw away a large part of the site and change the rules regarding homework.

There is a very strange story with the Physics site. Before joining SE, we had ten Q&A sites in the Russian language. Most of them were too small. After the migration, we switched them to a read-only mode, and then after a few years shut them down. For some reason, I forgot to switch the Physics site to read-only mode. When it was time to shut the sites down, I realized that there were still some active users on that site.

Any plans for the future?

No plans. Occasionally I do some maintenance on the server but nothing more.

  • Considering that what was once the global meta for sites that were run on your network, meta.hashcode.ru, now redirects to ru.meta.stackoverflow.com, on which only questions about Stack Overflow in Russian would be on-topic, where are users of Mathematics and Physics supposed to ask meta questions? Do they have per-site metas? Oct 11, 2018 at 14:53
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    Also, there's a link to careers.hashcode.ru which gives a 500 Internal Server Error; can that link please be removed? Oct 11, 2018 at 22:27
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    @SonictheAnonymousHedgehog It should happen one day... Nov 16, 2018 at 10:31
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    "Occasionally I do some maintenance on the server but nothing more" - so essentially what you did was let it die and become spam host. Sorry but that is NOT good. Just close it down and all will be good, I really can't understand why keeping something you can't take care of. Feb 27, 2022 at 10:59
  • math.hashcode.ru is down for a few days. Is it temporary, or does it mean the site came to an end? Feb 3 at 1:41
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    @MaxAlekseyev unfortunately, I faced an issue. Hetzner, the hosting provider that we had been using for last 12 years, has deleted all the data on the servers where the math.hashcode.ru was, including our backup infrastructure. They decided to do not work with people who have Russian passports (thought it is worth mentioning that the initial source of this problem is Roskomnadzor). I am still figuring out what I can do to recover the data. Feb 6 at 8:00

From https://vc.ru/story/11103-knowledge-network-stack-overflow

Спустя два года — в июне 2015 года — стало известно, что Stack Overflow выкупила «Сеть Знаний». Основатель компании Николай Чабановский перешёл на работу в Stack Overflow, а сама база вопросов и ответов оказалась частично перенесена на новый движок.


Two years later — in June 2015 it became known that Stack Overflow bought the "Knowledge Network" (sezn.ru). The company's founder Nicholas Chabanovsky got a job in StackOverflow, and the base of questions and answers was partially ported to a new engine.

From https://chat.stackexchange.com/transcript/22462?m=35595293#35595293

У нас есть сервер компании, к которому на самом деле доступ только у меня есть. На нем Математика крутится.

На этом сервере раньше работал ХэшКод и вся Сеть Знаний. Затем мы мигрировали что–то, что–то закрыли. Осталась только Математика, которая активна, но там одна домашка. Участники Математики не согласились выпиливать пол сайта и менять правила, запрещающие ДЗ. Как результат, сайт остался на старом движке. Поэтому компания поддерживает старый сервер.


We have a company's server that only I actually have access to. That's where Math site is hosted.

This server used to run Hash Code and the entire Knowledge Network. Then something was migrated, something closed. Only Mathematics remained active, but it consisted largely of homework questions. Mathematics users did not agree to throw away a large part of the site and change the rules regarding homework. As a result, the site remained on the old engine. Therefore, the company supports the old server.

So, it looks like StackExchange is actually involved in these remaining *.sezn.ru sites, but there are no plans on porting them to SE engine or actively developing them. They are just maintained as is.

  • "They are just maintained as is" - sadly, not even this. The company's founder did not do any such thing, and these days it's just full of spam. Feb 27, 2022 at 11:01

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