Consider the question Big O exponential: proving NP is a subset

Asymptotic notation questions have been pretty standard for Stack Overflow. This fairly interesting beginner question is up, but has already accumulated a couple of 'close' votes. One of them is for 'off topic' but, possibly because I'm a theory guy, it seems very much on topic for programming and related topics.

You could argue for "computer science" potentially, but it would seem this, like questions on, oh, NP-complete problems and such, are things serious professional programmers should know and are interested in.

You could also make a case for mathematics and event the theory stack, although it's probably a little light for theory. But with all of these separate categories, there seems to me to be a real risk that interesting questions will be modded/closed/moved until the OP loses interest.

Perhaps we've gotten a little too compartmentalized?

  • 4
    Honestly if I were interested in CS I would much rather ask on a site other than Stack Overflow...way too much noise, that's part of the reason for the separate sites. But if it's actually on topic that doesn't mean it needs to be closed to move to where it's more on topic, we've had numerous debates on this
    – Ben Brocka
    May 25, 2012 at 21:49
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    Yeah. It might be that it's incorrect to partition things as strongly as the various Stacks do -- maybe "CS" and "programming" and "admin" should be some kind of supercategories instead. May 25, 2012 at 22:02
  • Are you saying that "serious professional programmers" are not computer scientists? May 25, 2012 at 23:47
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    Well, I could name some serious computer scientists who aren't programmers, I'd go that far. But if the set of serious professional programmers is identical with the set of computer scientists, then having Stack Overflow and another Stack for Computer Scientists is redundant. May 26, 2012 at 5:40
  • @CharlieMartin: I never said that they were identical. However, among "serious professional programmers", if they've gotten the point where they are "serious" and "professional", then they probably already have some computer science under their belts. Either from formal education or from picking things up as they go. And, as you point out, there are computer science professionals who do not practice programming. So while there's an intersection, neither is a full subset of the other. May 26, 2012 at 6:16
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    Very much agreed. I don't see the point in fracturing communities up into little bits. Computer programming and computer science should all be on topic for Stack Overflow. General computer usage should all be on topic for Super User. We don't need Ask Ubuntu, Ask Different, Computer Science, Theoretical Computer Science, and all of the other duplicately-scoped sites. I think tags are perfectly adequate for keeping content separate and letting people find what they want. But the rest of the community strongly disagrees with me, apparently. May 26, 2012 at 8:33
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    @TheEstablishment -I think you make a very large oversight. AU is featured in the Ubuntu installer because it is Ubuntu targeted. I tend to think of AU as Ubuntu targeted questions, UL as general linux questions, SU as general computer questions, etc. To directly address your concern about tags, what is the maximum number of tags for any question? So if you have a question about a specific release of Ubuntu, a specific architecture, specific software, specific other requirements, etc...you may not be able to tag it appropriately. We also don't have a one book encyclopedia <-- case in point. May 26, 2012 at 10:11
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    I am a fairly established user on both AU and SU. Just for the record. May 26, 2012 at 10:12
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    @TheEstablishment: I agree with you. Having too many sites with topics that overlap with stackoverflow main site makes it harder for the community to find answers. Perhaps some of those sites with less than 10,000 questions should merge back into the main site? May 26, 2012 at 10:12
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    @akin I didn't say I didn't understand the split. I said it was unnecessary. You could just as easily feature Super User in the installer and ask people to tag their questions [ubuntu]. You can have 5 tags per question. I haven't heard of anyone running out of space for tags yet. I don't think this is a real problem. Tags don't need to cover all of the specifics, that's what the question body is for. And the reason we don't have one book encyclopediae is because the entries don't all fit in a single book. That's not a problem with websites... May 26, 2012 at 11:11
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    You weren't banned from chat because you disagreed with me, @akin. Promise. May 26, 2012 at 12:04
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    In an indirect manner, this highlights the point of having multiple sites. Having multiple communities is good. It's bad if they become warring states, but it's good that people form supportive groups. The flavor of interaction on Ask Ubuntu is not the same as on Stack Overflow and it has to do with the types of queries we get and the interests of the people here. I would wager the attitude of people focusing on Ubuntu is different than people who focus on programming queries, for example. --Chan-Ho Suh in AskUbuntu Chat
    – Amith KK
    May 26, 2012 at 12:07
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    @TheEstablishment Lets continue this in chat
    – Amith KK
    May 26, 2012 at 12:15
  • Sorry, I don't do chat. I was specifically trying not to open a discussion about this in the comments of someone else's question by stating my opinion, but lamenting that the community doesn't agree with me. I get it, you don't agree with me. May 26, 2012 at 12:18
  • Okay, I'm sorry, but a question in 2017 expanding on my point in this question in 2012 is NOT a duplicate of the 2017 question. Apr 4, 2018 at 20:40

2 Answers 2


Just because a question could be asked on multiple sites doesn't mean it must be asked only one of them. If a question is on-topic on Stack Overflow, and ask there, it should stay there:

As members of a community, your first loyalty should be to that community. When evaluating a question, you shouldn’t be looking to push it off on some other site; instead, ask if it could be appropriate and on-topic for you, the experts who the author decided to ask. Be a bit jealous of your site – don’t blithely turn askers away simply because their question could be asked somewhere else. Don’t hit them over the head with your scope, help them tailor their question to fit into it – and if that means your site’s scope overlaps a bit with another site’s, so be it.

There are plenty of questions on Stack Overflow that could be asked on Programmers or Computer Science or Database Administrators or Game Development or Super User or even Mathematics or Physics. But if you're looking for an answer from the programmers on Stack Overflow, none of that should matter.

Now, if someone happens to think the asker could get a better answer on another site - or knows of a similar question already answered on another site - politely offering a link to it would be helpful. But that's no reason to close it.

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    That's certainly among my concerns -- I don't have the time or ambition to read all the Stacks that I have an interest in, and I've got a long history of answering these grad-school-ish questions in what I hope is a useful way. May 25, 2012 at 22:04
  • And on the flipside, one can find dedicated communities on smaller sites made up of people who aren't interested in using SO due to its sheer size or an abundance of other topics. There are pros and cons to targeting either audience.
    – Adam Lear StaffMod
    May 25, 2012 at 22:04
  • Anna, is that meant to be an argument that it's good to close apparently topical questions on SO? May 25, 2012 at 22:08
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    @CharlieMartin Not at all; just that the existence of niche sites isn't necessarily a problem in and of itself. If someone becomes aware of a niche site and decides to take their questions there instead of SO, it's not always a bad thing.
    – Adam Lear StaffMod
    May 25, 2012 at 22:10
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    Is it worth thinking about ways to show a question on multiple sites, while having it "rooted" in just one site?
    – Pekka
    May 26, 2012 at 0:12
  • @Pekka: seems like that would just provoke arguments; that would be a much truer implementation of cross-posting, with all the inherent problems of culture clash that it entails - for those rare questions that do get asked, legitimately, on multiple sites, cross-linking should suffice - and is much easier to implement ;-)
    – Shog9
    May 26, 2012 at 0:32
  • @Shog cross-linking is more what I mean. What I've had in mind for a while is a system that shows good questions that have a tag-match with some other site, on that other site, as external links in some form (although it would be cool to see the question in context of the site you're browsing, allowing you to comment and answer without leaving the original site... but that would bring other issues. Not sure.)
    – Pekka
    May 26, 2012 at 11:01
  • Users could hide these out-of-towner questions through the tagging system (they get a special tag). Say, a hard c++ question on gamedev that gets a couple upvotes and gets shown to the SO c++ tag. There would be many implementation issues and problems to solve with this (would the "tag match" thing really work? How to define the "migration paths" on which this would work? etc.), but it could be a once-and-for-all end to crossposting, as you can rest assured that your question, if it's just halfway decent, is gettign the maximum possible exposure across sites.
    – Pekka
    May 26, 2012 at 11:02
  • The one thing that I'm unhappy about in this idea is that many users will not want to answer a question that was asked on gamedev.SE because they don't care for the rep there. It's not perfect for "career answerers" who are mainly interested in raising their score. But those can simply suppress the appropriate tags (like say, from-gamedev, giving from-* tags a special role or whatever.), plus inter-site answering can be awarded with some cool badges.
    – Pekka
    May 26, 2012 at 11:07
  • I'm open to the idea that it's not a huge problem, though. It seems one to me because I get the same feeling (that of insecurity where to ask something, and where to get the best response) very often when I have a question.
    – Pekka
    May 26, 2012 at 11:22
  • I agree with this general rule. However, as member of the Stack Overflow community, I consider this question off-topic. May 26, 2012 at 12:22

About this specific question

I voted to close as off-topic. I don't see a programming question here, or an algorithm question.

questions on, oh, NP-complete problems and such, are things serious professional programmers should know and are interested in.

Not everything that serious professional programmers are interested in are on-topic on a site about programming. Favorite programmer cartoons, software licenses, project management, filing income taxes, Charles Stross novels… These are all things that programmers tend to be interested in. That doesn't make them on-topic on Stack Overflow.

The question would be on-topic on Computer Science and on Mathematics. It's fundamentally a math question, but this is math that's applied to CS, which makes the question on-topic on CS as well.

About the need for separate sites

The still relatively new Computer Science site arose out of a need. Stack Overflow does not work as a computer science site. I refer you to the many prior discussions on the topic; I think this thread on Meta.CS is a good overview, and the main discussions that led to the existence of the site are Where on SE to discuss computer science and How can we better serve the CS community on Stack Overflow?

the set of serious professional programmers is identical with the set of computer scientists, then having Stack Overflow and another Stack for Computer Scientists is redundant.

I agree with the implication. However, since the two sets do not in fact have a very large intersection, having separate sites seems justified on this basis.

  • Not everything that serious professional programmers are interested in are on-topic on a site about programming. I'm stealing that for the Programmers FAQ.
    – yannis
    May 26, 2012 at 12:23

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