There's been a lot of chatter of late about our scope, the declining number of questions being asked per day, and whether we're being excessively strict about question scope.

This question is intended to revisit the debate over scope. I'll outline some reasons why I think it's a good idea to revisit the question, and propose a new scope definition that we can debate.

Why revisit our scope ?

Our original intent in defining our scope was to shelter the site from a potential deluge of basic algorithms questions, and to model our community on the very successful MathOverflow model. I think two things have changed since that time:

  1. We now have a natural forum (cs.stackexchange.com) for the more "basic" algorithms questions, and the cstheory "brand" is well established as a 'research-only' venue. So we have an easy process to shunt questions that are obviously undergrad level.

  2. As has been observed, our overall participation numbers have slowed, as well as the pace of new upvoted questions. Given how many people I personally know who aren't active on the site, I see no reason why our numbers should be slowing.

My view of the problem

We are not the same as the mathoverflow community. TCS is much smaller to start with, and there's a much smaller gap between the "starting grad student question" and "advanced research question" in TCS than in math. By limiting ourselves to the research end of the spectrum, we are

  • excluding questions from people who might be 'research-level' in a sub area but aren't experts in some other domain. This is often mitigated by reputation (I might be able to get away with asking a basic complexity theory question), but it shouldn't be !
  • creating the impression of an unfriendly site (which is a bigger problem in terms of maintaining the audience)
  • spending far too much time policing the boundaries of what's acceptable, instead of being willing to accept some small fraction of lower-level questions in order to also bring in more interesting ones.

A proposal

We should allow questions that might be asked by a grad student in a grad theory class, even if they are not 'research-level', as long as they are looking for a deeper understanding. For example, a question "What is Sauer's lemma' could be dismissed because it's on Wikipedia, but "How should I go about proving an upper bound on VC dimension" would be ok.

This is not perfect as examples go, and I'm happy to hear modifications and suggestions.

But please keep the discussion constructive and focused. Just because your questions are closed doesn't mean that there's a problem. Conversely, just because you like the site just as it is doesn't mean you can't try to imagine something even more useful to the community.

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    $\begingroup$ Btw, there are some similar discussions ongoing on MO's meta, the latest one is Relation between MO & MSE. $\endgroup$ – Kaveh Aug 9 '12 at 9:31
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    $\begingroup$ "spending far too much time policing the boundaries of what's acceptable, instead of being willing to accept some small fraction of lower-level questions in order to also bring in more interesting ones." This in my mind is one of the most depressing occurrences here. When you see a discussion on a question that is longer than the question itself, simply endless bickering about scope, it seems like we're doing it wrong. $\endgroup$ – Josephine Moeller Aug 9 '12 at 9:41
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    $\begingroup$ Case in point: mathoverflow.net/questions/19152/… - this is a very basic question, but gets a great response from Terry Tao. This is what I meant by "questions that look for a deeper insight" $\endgroup$ – Suresh Venkat Aug 9 '12 at 12:55
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    $\begingroup$ but we should be more professional about closing questions. there is little point in excessive downvoting and even less point in numerous "this is out of scope" comments. if we think something dos not belong, let's just vote to close it, without much discussion. if OP has a problem, they may always post on meta. $\endgroup$ – Sasho Nikolov Aug 9 '12 at 15:56
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    $\begingroup$ @Suresh, I disagree about this being a very basic question. "Why" questions are subtle and rarely asked. I would not expect a similar theoretical computer science question (for example: "Why is a Turing machine defined as a 5-tuple?") to be closed here. $\endgroup$ – Jeffε Aug 9 '12 at 16:53
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    $\begingroup$ I think it's not entirely fair to judge the health of the site by its traffic over the summer, when a significant fraction of TCS researchers, especially students, are away from their desks. I support Suresh's proposal, but I also expect traffic to pick up significantly in about a month, when the fall semester/quarter is in full swing. $\endgroup$ – Jeffε Aug 9 '12 at 16:56
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    $\begingroup$ Why do we have to lower our standards instead of just allowing questions from research-level non-theory domains (say ML/AI, or a lot of the great questions at SciComp) and encouraging more application-of-theory questions? $\endgroup$ – Artem Kaznatcheev Aug 9 '12 at 18:30
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    $\begingroup$ @SashoNikolov: Closing a question without comment is not "more professional"; it's just less friendly. All those "out of scope" comments might look redundant to us, but most people who post out of scope question see only one of them. $\endgroup$ – Jeffε Aug 9 '12 at 19:29
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    $\begingroup$ @vzn Put a sock in it. You posted that question in bad faith, and you're continuing to push your agenda using bad faith arguments. Or are you just trolling at this point? $\endgroup$ – Josephine Moeller Aug 9 '12 at 22:50
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    $\begingroup$ @vzn You posted a question (without proper motivation), knowing that it would be downvoted. That's a pretty clear example of bad faith. If you have examples of the questions that you're talking about, link to them. Quit posting new questions with cynical intentions. $\endgroup$ – Josephine Moeller Aug 9 '12 at 23:32
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    $\begingroup$ @vzn I'm sorry you feel that way. And if I'm wrong about your intentions, I'm sorry about that too. I really am. Several people have tried to convince you that you're going about this the wrong way. And as for groupthink, if you can't see that isn't true, I don't know what else to say. $\endgroup$ – Josephine Moeller Aug 10 '12 at 0:27
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    $\begingroup$ @vzn did you read my comment on your question? you put zero effort in trying to understand on your own. my first question was upvoted to above 20 and I had little rep at the time, i am not well known, or anything. i just had thought about what i asked and wrote out motivations and the facts (facts not tangential refs) that I knew. $\endgroup$ – Sasho Nikolov Aug 10 '12 at 6:38
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    $\begingroup$ There seems to be a lot of demand for discussion. Given that this platform works badly for that, I suggest you schedule a (moderated) chat meeting. $\endgroup$ – Raphael Aug 10 '12 at 7:11
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    $\begingroup$ @vzn: Please stop putting words in my mouth. $\endgroup$ – Jeffε Aug 10 '12 at 14:52
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    $\begingroup$ @vzn pure theory lacks applications, not motivation $\endgroup$ – Tyson Williams Aug 12 '12 at 4:34

I'm in favor of rejecting undergraduate (and most graduate) homework problems, admitting anything that seems to come from a practitioner with a real theory question (however easy) that arises in practice, and using judgment for the other cases. There is an overlap in level between the first two, but I think you can often tell from the question which is which, and if you can't, we can query the OP to decide.

My reasoning is: if you encourage questions from people with real problems, you will occasionally get very interesting theory problems that somebody actually cares about, and I'd like to see more of these. If you encourage questions from people with homework problems, all you'll ever get is a deluge of even more homework problems.

I don't think we should close questions from practitioners as being at too low a level, as this sends out a message "don't ask us questions; you're too stupid". If we get a lot of questions whose answer is, say, the assignment problem, we could close them as duplicates of each other, even if the questions aren't exactly the same.

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    $\begingroup$ Agree. Homework problems are annoying. But it seems like these are pretty obvious in most cases. OPs who ask them don't seem to justify them at all, even after prodding. $\endgroup$ – Josephine Moeller Aug 9 '12 at 19:27
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    $\begingroup$ I think that any question that makes you think, "geez, I wish that I had asked that when I was a grad student," is a good question. $\endgroup$ – Josephine Moeller Aug 9 '12 at 19:29
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    $\begingroup$ You can not effectively decide what is homework and what is not. So, if you expand the scope like this you may as well join forces with cs.SE. $\endgroup$ – Raphael Aug 9 '12 at 22:36
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    $\begingroup$ @Raphael: there are a lot of questions on cs.se that are obviously homework. Just because we can't decide in all cases doesn't mean that we can't decide enough of the time to (1) not have the site degenerate into somewhere that can't answer difficult questions and (2) not drive away anybody who isn't getting a graduate degree in TCS. $\endgroup$ – Peter Shor Aug 9 '12 at 22:39
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    $\begingroup$ @JohnMoeller: I think it's part of the cstheory community who is afraid of "homework questions" for a reason I don't quite get. The inability to distinguish homework outsourcing from "real" questions made us drop the distinction on cs.SE. Essentially, it is up to the users whether they want to read and/or answer a question. $\endgroup$ – Raphael Aug 9 '12 at 23:12
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    $\begingroup$ @Raphael There's also the fact that the floodgates have already been opened. As was pointed out by (I think) Kaveh, Google searches bring people here first, so people ask homework questions anyway. There's no reason we can't just answer the ones that are interesting at a research level and downvote the rest. $\endgroup$ – Josephine Moeller Aug 9 '12 at 23:25
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    $\begingroup$ @Raphael No, that's the wrong question. The SX sites are supposed to evolve with their communities. If we draw clear scope lines, with lots of rules about how the boundary is defined, we lose the ability to evolve. We need to think more in terms of general guidelines. $\endgroup$ – Josephine Moeller Aug 9 '12 at 23:38
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    $\begingroup$ @JohnMoeller: If the guideline is "If I like your face, your question is ok" (which some proposals here come close to), I have to oppose that. $\endgroup$ – Raphael Aug 10 '12 at 6:35
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    $\begingroup$ Peter, what do you think about migrating practitioner questions to Computer Science? I mean those question are alive and a researcher can follow them if he wants. The only objection I can see for that is that a person might not be interested in other questions on Computer Science, but then it looks to me that the core issue is that different people have different interests and everyone seems to want to have all of the questions they are interested in and only those question in one place. $\endgroup$ – Kaveh Aug 10 '12 at 6:50
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    $\begingroup$ You want a) research + practitioners - undergrad, another user wants b) research-level only, yet another one wants c) research + practitioner + undergrad. Putting aside the practical issues regarding their feasibility and implementation, they are inconsistent goals, we cannot satisfy all of these completely at the same time. From the perspective of site's health what is required IMHO is keeping researchers actively interested in the site, and that means 1) getting questions in the area of their expertise, 2) avoid getting too many uninteresting questions. Other items are secondary in my view, $\endgroup$ – Kaveh Aug 10 '12 at 6:53
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    $\begingroup$ @Raphael I think that's a bit reductive. Do you seriously think that we can create a totally objective set of constraints for questions? We can't even do that for our conferences! We have to rely on judgment here. $\endgroup$ – Josephine Moeller Aug 10 '12 at 7:02
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    $\begingroup$ @JohnMoeller: Yes, but the object being judged has to be clear and available (e.g. a paper, a question text) and not some cloudy thing (e.g. the questioners alleged background or motivation). (No, by the way; "but it's done wrong there, too!" is not a valid argument.) Keep in mind that cstheory is perceived as elitist already; if you add judgemental on top of that, I am not sure what the greater SE community will think. We do not have to care, but we are part of that in the end, and whether Oversight "likes" us might decide the fate of cstheory one day. $\endgroup$ – Raphael Aug 10 '12 at 7:09
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    $\begingroup$ @Kaveh Don't condescend to me. $\endgroup$ – Josephine Moeller Aug 10 '12 at 7:22
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    $\begingroup$ @Kaveh Passionate disagreement != personal stake. I only speak for myself because I can't speak for others. Now I'm taking it personally because you made it personal. Cut the paternal crap. $\endgroup$ – Josephine Moeller Aug 10 '12 at 7:25
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    $\begingroup$ @Raphael Ok, but with all due respect, this discussion is about making TCS.sx better, not protecting CS.sx. $\endgroup$ – Josephine Moeller Aug 10 '12 at 19:38

We should allow questions that might be asked by a grad student in a grad theory class, even if they are not 'research-level', as long as they are looking for a deeper understanding. For example, a question "What is Sauer's lemma' could be dismissed because it's on Wikipedia, but "How should I go about proving an upper bound on VC dimension" would be ok.

This seems like a good start to me. Especially as someone from a university with a small theory group, having a reference on certain proof techniques would be great.

I think that we could agree that the following examples are too broad/ill-formed:

  • How do I prove a lower bound?
  • How do I use the Lovasz Local Lemma?

But perhaps the following is a bit more focused:

  • Is a cell probe lower bound appropriate for X application?

I'm interested to hear thoughts on this aspect.

  • $\begingroup$ I like the cell probe example. that's definitely a good one. $\endgroup$ – Suresh Venkat Aug 9 '12 at 12:56
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    $\begingroup$ I am actually wondering when is a cell probe lower bound not appropriate? In my mind if you cannot do something in the cell probe model you most definitely cannot do it in any computer that I have seen. Of course this is not the topic of the question :) $\endgroup$ – Sasho Nikolov Aug 26 '12 at 19:31

Though the scope of this site is mostly defined in terms of topics and level, clientele is another important factor. For question that are in the overlap between here and 'general audience' sites, the difference is mostly in the type of answer that such questions get. In such cases, users may prefer one site over another depending on the type of answer they want.

For example, I am a mathematical logician, so my relation with TCS is mostly tangential. As a result, my knowledge of the field is very uneven. It's fairly common for me to encounter something in TCS that I don't know but is not necessarily that high-level, something that a young graduate student in TCS may ask. However, the student and I need very different types of answer to this question. On the one hand, a carefully crafted and detailed answer makes a lot of sense for the student since they are seeking to learn more and hone their skill set. On the other hand, a brief explanation skipping over routine steps is perfect for me. I really just need to plug a gap in my knowledge base, my general skills are already well developed so I can easily fill in the missing steps. Even if the question is the same, it's better for me to ask it here and it's better for the student to ask elsewhere.

I think the scope of this site should allow this kind of flexibility. It wouldn't hurt to be explicit about this in the statement of purpose. This is also a good place to remind users to add motivation and background for their question. Otherwise, it's very difficult for the community to assess whether this is the right place for a borderline question. This is difficult, but it's not a bad idea to try to cultivate a certain level of tolerance for questions that are not clearly out of scope. Users who do not find the type of answers they want will eventually find their way elsewhere.

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    $\begingroup$ I agree completely with this. $\endgroup$ – Neel Krishnaswami Aug 13 '12 at 9:04
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    $\begingroup$ This is one of the use cases I'm most interested in encouraging, and I agree that providing some motivation in each case might help. $\endgroup$ – Suresh Venkat Aug 14 '12 at 5:26
  • $\begingroup$ Thank you for this answer! You are saying much better what I think I failed to communicate in my comments to @Raphael. $\endgroup$ – Sasho Nikolov Aug 26 '12 at 19:34

I think there are several issues here that are being confused. I'll number the issues and give examples to illustrate the point. I'm not really advocating anything in this post, I'm just trying to clear the confusion. It seems to me that people are talking past each other just because they're arguing about different issues

Issue 1: "Deep understanding" questions.

I think everyone would be fine with the OP demonstrated understanding of the standard answer and asked for a deep understanding.

Non-example: "What's the definition of AC0?". This question can be answered by reading any standard text on circuit complexity, and thus should be closed.

Example: "Why does AC0 allow unbounded fanin AND gates? NC0 has a gate-independent definition (allow all 2 input gates), why does AC0 focus on AND/OR gates? Changing the gates changes the class, so what's the motivation?" This is an interesting question, and someone on this site might have an excellent answer. It should remain open.

Conclusion: I think Issue 1 is a non-issue. I don't think we are divided about this issue. If the OP demonstrates understanding of the standard answer and asks a "motivation" or "understanding" type question, I think people wouldn't vote to close. (Please leave a comment if you think this conclusion is incorrect.)

Issue 2: Is the function IsInScope() solely a function of the question or does it also depend on who asked it?

This is the issue raised by Peter. While we don't want to entertain undergrad homework questions, often questions from people outside the field are at the level of undergrad homework questions.

Example: "I'm stuck on this problem [followed by a description of the problem] while designing a maze-navigating robot. Any suggestions on how to solve it?" Answer: "This is NP-complete using the following simple reduction from longest path. However, you could try the following heuristics."

Any problem that is a simple reduction from longest path might be an assignment problem in an undergrad course. So if this were asked by an undergrad, we should close it. But Peter suggests that it should be kept open if asked by a practitioner outside the field.

Conclusion: This issue is not resolved. I don't think people are in agreement about what to do about this or how to distinguish whether the OP is an undergrad or a practitioner in another field.

Issue 3: Grad level questions: Should we lower the bar from research-level to grad-level?

These are questions that would be considered basic grad level in field X by persons who study field X. However, as in Issue 2, these might come from people outside the field, for whom the question is not easy at all. But let's assume that questions come from grad students in the field so as to not confuse this issue with Issue 2.

These questions might be homework questions for grad courses (which means they can be difficult questions) or questions asked by grad students to the instructor during/after class.

Maybe this issue separates into two issues. The first is about grad-level homework questions and the second is about questions asked by a grad student, which are not research-level, but the answer can be found in a grad-level text book.

Conclusion: Currently I don't think there is consensus on this. Grad-level homework questions are sometimes closed. Questions whose answers are in grad-level text-books are often closed. It's not clear if the proposal is to change this situation or not.

  • $\begingroup$ regarding 2, IIRC, the conclusion of the previous discussion on the issue was something close to what Peter is saying here, i.e. a) practitioner questions are on-topic (as long as we are not getting too many), b) in unclear cases, to distinguish between practitioner from undergrad, we will ask the OP to provide motivation for the question. $\endgroup$ – Kaveh Aug 9 '12 at 17:37
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    $\begingroup$ @Kaveh: I think there is disagreement on the specifics and implementation of this policy. Peter and you had a long discussion on your answer, which is why I think it's not clear that everyone agrees on how to implement this policy. In any case, I just wanted to separate the issues so that people aren't confusing them. For example I think Suresh's original question is about Issue 1 and 3, whereas Peter's post and the comments to your post are about Issue 2. $\endgroup$ – Robin Kothari Aug 9 '12 at 18:02
  • $\begingroup$ yes, I just wanted to remind the conclusion of the previous meta-discussion on the issue. $\endgroup$ – Kaveh Aug 9 '12 at 18:22
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    $\begingroup$ I think one of the hearts of this issue is this false dichotomy between undergrads and practitioners. There is a large spectrum in between, largely populated by beginning grad students, who are learning how to be practitioners. $\endgroup$ – Josephine Moeller Aug 9 '12 at 19:25
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    $\begingroup$ Off-topic comment: That you consider grad-level != research-level is concerning. $\endgroup$ – Raphael Aug 9 '12 at 22:40
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    $\begingroup$ @Raphael: I couldn't come up with a better name, but I'm sure you know what I mean. I remember asking questions in class which could have been answered by reading the text book. But those questions aren't research level. $\endgroup$ – Robin Kothari Aug 9 '12 at 23:41
  • $\begingroup$ @RobinKothari: Honestly, I don't know. I don't think such a thing as "grad level" exists. Different grad students know or don't know different things. Stuff I learn in a specialised lecture in my bachelor's might be completely unknown to 90% of all researchers. $\endgroup$ – Raphael Aug 11 '12 at 10:57

We should be specific not only about what is on-topic but also about what is off-topic.

I think typical questions at the level of undergraduate homework/assignment/textbook exercise should remain off-topic, i.e. a question is off-topic if

  • it is an exercise from a standard undergraduate textbook, or
  • it is a typical assignment/homework problem in a typical undergraduate course on the topic.

I think the idea of this lower-bound on cstheory's scope boils down to the following:

A question is off-topic if a typical (or maybe even somewhat bright) undergraduate in CS who has taken a typical undergraduate course (or has read a typical undergraduate-level textbook) on the topic is expected to know the answer.

An exception can made for questions where the OP shows that they know the standard answer to the question and explicitly ask for a deeper understanding or insight (which a typical undergraduate is unlikely to be able to provide).

I think this is a lower-bound if we want to keep the attention of the target community of the site (TCS researchers in academia/industry and graduate students, i.e. people whose job is research in TCS). If we go below that level I think we will loose users from that community.

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    $\begingroup$ I think a "question at the level of undergraduate homework assignment/textbook exercises" should be off-topic if it comes from somebody who encountered it as a textbook exercise. Let's take a variant of the SMAWK algorithm. If the homework exercise is "modify the SMAWK algorithm to solve this problem", it might be easy. If somebody who has never heard of the SMAWK algorithm is trying to develop an algorithm for the same problem, it's not at all easy, and in fact this problem might stump CS researchers who last heard of the SMAWK algorithm in a class 10 years ago. And it's the same question. $\endgroup$ – Peter Shor Aug 9 '12 at 15:09
  • $\begingroup$ @Peter, we had a discussion about that also IIRC, and I think the result was adopting the application-of-theory tag. Doesn't this address your concern? $\endgroup$ – Kaveh Aug 9 '12 at 15:13
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    $\begingroup$ Not if people are currently closing questions from practitioners for being at too low a level. $\endgroup$ – Peter Shor Aug 9 '12 at 15:16
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    $\begingroup$ @Peter, I think the issue is that we cannot know if it is from a practitioner unless the OP tells us it is so. If you notice a case please add the application-of-theory tag and flag it for moderator attention and we can reopen the question. $\endgroup$ – Kaveh Aug 9 '12 at 15:18
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    $\begingroup$ This question for example, clearly wasn't homework, and so should not have been closed so precipitously, even if it wasn't very well-formed. $\endgroup$ – Peter Shor Aug 9 '12 at 15:32
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    $\begingroup$ I think the problem is that we have the "guilty until proven innocent" rather than "innocent until proven guilty" mindset. If a question is clearly homework, or clearly from somebody who wants to understand something about theoretical computer science they should learn from reading Wikipedia or an undergrad textbook, we should close it. Otherwise, we should leave it open. Working at Bell Labs for nearly two decades, I learned that questions from practitioners are typically vague and ill-formed, but if you talk with them, you very often get clearer questions which are often quite interesting. $\endgroup$ – Peter Shor Aug 9 '12 at 15:41
  • $\begingroup$ @Peter, is that an application of theory question? It seems more like a programming/implementation question to me, have a look at the other question the same user posted around the same time. cstheory is not a coq help forum as far as I know. (An analogy for how I see the question: how can I fix the following C++ code, I am getting compile error X on g++). If you think the question should be reopened please start a new meta discussion. IIRC I closed them after 1 day or so and no reply from the OP to the comments. $\endgroup$ – Kaveh Aug 9 '12 at 16:54
  • $\begingroup$ @Peter, I think we have already agreed that application of theory questions are on-topic (IIRC, as long as we don't get too many). Closing is not permanent, the general practice is that when a question is not fit it is closed, when the question is edited to become fit it is reopened. I would not call this "guilty until proven innocent", we tell the OP that the question is not fit, if the OP engages and improves the question fine, if after sometime there is no reply we close the question until the question is improved to become fit. And we also tell these to the OP using comments/FAQ. $\endgroup$ – Kaveh Aug 9 '12 at 17:03
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    $\begingroup$ Look at it from the OP's point of view. His question, on a stackexchange site he doesn't understand that well, has just been rejected by a bunch of really smart people who are generally university professors. Is he going to argue with us? $\endgroup$ – Peter Shor Aug 9 '12 at 17:32
  • $\begingroup$ @Peter, I understand your concerns and do find them valid. My main concern here is to have a workable solution, everyone has good intentions but we should also consider the general consequences of these decisions. Are we going to leave these questions open indefinitely even if the OP doesn't engage? How many undergrad questions will pass as unclear cases if we do so? Would that make the scope meaningless? What will be the effect of these on the participation of researchers? $\endgroup$ – Kaveh Aug 9 '12 at 17:44
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    $\begingroup$ @PeterShor: I don't agree that "How do you modify SMAWK to do X?" and "How do you do X?" are the same question! (Also, SMAWK is (sadly) not covered in most algorithms classes, so it's not clear even the former question would be closed.) $\endgroup$ – Jeffε Aug 9 '12 at 19:35
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    $\begingroup$ Here's my own judgement about what constitutes a "homework question": If I have asked that precise question on an undergraduate algorithms exam, it's a homework-level question. If I've given the question in an undergrad algorithms homework, and most of the students got it, it's a homework-level question. If it strikes me as a perfect question to ask the undergrad algorithms class I'm currently teaching, then it's probably a homework-level question. Otherwise, it's not. $\endgroup$ – Jeffε Aug 10 '12 at 15:04
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    $\begingroup$ @JɛffE: That's not a very good heuristic (for maintaining the site), as it does not transfer to others (i.e. mods) and probably does not work outside of your area of expertise/teaching. $\endgroup$ – Raphael Aug 11 '12 at 10:55
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    $\begingroup$ @Raphael: Maybe I should say "Otherwise, I assume it's not." Not that I'll insist that it's not. $\endgroup$ – Jeffε Aug 11 '12 at 13:33
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    $\begingroup$ @peter -- aggressive yet inappropriate "guilty until proven innocent" attitude is spot on. had two application-of-theory questions closed/downvoted aggressively recently. & kaveh the tag warrior didnt add it. didnt notice that tag until now.. ouch, its perfect for a lot of my questions. would edit them to chg the tag, but am sure its not gonna help the votes. live & learn, 2020 hindsight. unfortunately kaveh seems to act like tags on questions are highly objective and not so subjective, see him declare strongly against tags I thought were highly appropos. guess some tags are "ghetto" $\endgroup$ – vzn Aug 11 '12 at 18:37

The question about scope is an important one. The answers and comments make one thing clear: we have not only to decide what we want, but also why we want it. Because in the end, whatever we do, we have to do it for the right reasons.

For example, why change the scope at all? So far, we have vehemently defended it against numerous incurions, shooting down arguments like low stats, ivory tower and lack of non-experts to ask questions with the argument that the community works and likes what it has. What changed? Some numbers and a couple of disgruntled people outside of our target group can hardly be the reason.

Another example, what are the real reasons for not allowing undergrad questions? Given that the same question has been proclaimed OK if it is asked by somebody who is not an undergrad student (be it practitioner or researcher of another field), the ban has the taste of hypocrisy; is the only reason something like "I don't want to be plagued by noisy students in my free time"? If so, that would be a weak reason¹.

That said, if the scope is to be changed, I see two possibilites:

  1. Extend vertically, that is non-research level TCS questions.
  2. Extend horizontally, that is to research-level questions in other CS subdisciplines.

Variant 1 is problematic in the light of the above. Either you create a very weird and not effectively enforcable set of rules, or you allow all TCS questions (which does not seem to be the dominant wish). The notion of "level" has always been squishy, but at least "research" is relatively clearly defined. "Grad-level" is already incredibly ambiguous².

Variant 2 is less problematic in principle but all but impossible practically: there are no experts of non-theoretic CS here (presumably), the site has its brand as "theoretical". I fail to see how you could get experts from other fields engaged here. Essentially, they would not want to for the same reasons the founders of cstheory did not want to be part of a all-encompassing CS community: low signal-to-noise ratio (because of the dominance of TCS).

In either case, we have to find an answer (with good reasons!) to the question: why not go all the way and join forces with cs.SE?³

  1. I strongly feel that the reason for rejection has to be found in the question. In particular, it has to be independent of the person asking. Otherwise, you get weird judgements and (perceived and actual) discrimination.
  2. We have grad students (in AI) that come to us with next to no TCS knowledge. Literally. They are taught things like finite automata from the basics up. So, would a typical undergrad question posed by an actual grad student (who is an undergrad in TCS) be ok?
  3. That would be a horrible idea right now, but it will hopefully become a viable option in the future.
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    $\begingroup$ Regarding your footnote (2), I can speak from personal experience. My BS degree is in mathematics, not CS. Honestly I get a bit intimidated by my lack of basic TCS knowledge and I'm too chicken to ask. For instance, there was a question on LL-something-or-other languages that I was clueless on and I wondered why it had been closed. I asked Suresh, and he told me that it was very basic automata theory. I didn't have any problem with closing it after that. I have to go in with the knowledge that my questions may be rejected due to lack of knowledge, because we can't accommodate everyone. $\endgroup$ – Josephine Moeller Aug 9 '12 at 23:43
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    $\begingroup$ I think you're being dense with respect to Peter's point. Questions motivated from practice can be clearly told apart from exercises and homework questions. Questions coming from practice can be interesting because they often show a different viewpoint or give perspective. Exercises are not interesting and do not belong because they're designed to test students: they simply cannot enrich the website. $\endgroup$ – Sasho Nikolov Aug 11 '12 at 9:27
  • $\begingroup$ @SashoNikolov: Apparently, that is not true at all (the answer comes from an undergrad exercise). You want more? This and this and this are all undergrad material, yet have been accepted as "enriching" the site. $\endgroup$ – Raphael Aug 11 '12 at 10:45
  • $\begingroup$ @SashoNikolov: As much as I like this site, the question acceptance criterion has never been the "level" of something, but whether enough high-rep people think the question is interesting, which also varies a lot over topics (point in case: complexity theory questions). That has always been problematic to some extent, and the problems would only increase if we intentionally muddied the "border" even more. $\endgroup$ – Raphael Aug 11 '12 at 10:51
  • $\begingroup$ @Raphael there is a difference between your first example and this. jkff's question is nice because it leads to a collection of answers each containing a different non-constructive proof technique. the CS@SE question is boring to anyone who passed a basic computability course (and to some who failed it) because it gives a single well-known answer. $\endgroup$ – Sasho Nikolov Aug 12 '12 at 0:18
  • $\begingroup$ of course level is not the primary thing. a question which puts something simple in a new light is great and we all recognize that: that's why we'd like to encourage practitioners to post their questions. but someone parroting his textbook exercises is simply too boring. we deal with enough textbook exercises when we TA or teach courses. $\endgroup$ – Sasho Nikolov Aug 12 '12 at 0:22
  • $\begingroup$ @SashoNikolov: If it were that well-known, jkff would not have needed to ask his question. Apparently he learned something new from a boring undergrad exercise. But that train of discussion does not lead us anywhere. We disagree; I don't think the dichotomy of levels some propose exists. (It even concerns me that researchers think that way.) There may be valid reasons for insulating an expert community from adepts, but that is not it. $\endgroup$ – Raphael Aug 12 '12 at 0:23
  • $\begingroup$ @SashoNikolov: Then I suggest you ignore the boring textbook question, or downvote it for lack of effort. Because that's the problem. An undergrad may shed new light on something, same as the practitioner. Your issue is simple restating of exercise material. So attack that, not the undergrad. (Note that we do that "even" on cs.SE. We expect our askers to tell us what they tried, especially on suspicious questions. Not all users follow suit yet, though, and answer such questions without second thoughts.) $\endgroup$ – Raphael Aug 12 '12 at 0:26

Disclaimer: I am a moderator on Computer Science Stack Exchange. While I try to judge this proposal on its own merit, it is likely that the time and energy I have invested in CS.SE influences me.

I'm afraid that broadening the scope in this way would destroy the existing community. A Stack Exchange site is defined by two things: the kind of questions it accepts, and the audience it attracts. Even though each question is in principle judged on its intrinsic merits, the long-term effect is to create a community.

On this site, the community is centered around researchers in theoretical computer science. Participants tend to be researchers in TCS, researchers in other fields, or graduate students aspiring to become researchers. The participants who are welcomed are generally those who came with the expectation of participating in a community dominated by TCS researchers.

I do not see a problem with allowing more applied questions. As long as academics and people who want to fit in with academics dominate the site, that isn't a problem. It may be difficult to bootstrap an applied CS community (it would have been a lot easier to do when the site was young), but if it works, it won't change the tone of the site, and if it fails, the site won't have changed.

On the other hand, opening the door to more basic questions means opening the door to a broader audience. This should be a carefully controlled process. In particular, I advise you not to try to draw on Stack Overflow as an audience base. A majority of Stack Overflow does not know or care what it means to be a scientist. The kind of people you would attract are those who now post on Programmers. If you attract those people, be prepared to moderate their content. And to moderate them.

Reacting to specific points in your proposal:

We now have a natural forum (cs.stackexchange.com) for the more "basic" algorithms questions, and the cstheory "brand" is well established as a 'research-only' venue. So we have an easy process to shunt questions that are obviously undergrad level.

Keep in mind that CS.SE is not exclusively for basic questions. It is for questions at all level, ranging all the way from CS 101 homework to applied research (and even research in theory, but we suggest CSTheory.SE to the rare asker who comes with a theory question that seems to go unanswered because it is too hard).

excluding questions from people who might be 'research-level' in a sub area but aren't experts in some other domain

From what I see (I admit to not following CSTheory.SE very closely), this already happens: as long as there's a feeling that peers are talking with peers, questions tend to be appreciated, left open and answered.

creating the impression of an unfriendly site (which is a bigger problem in terms of maintaining the audience)

I think the community is doing an adequate job of retaining the audience it likes in and keeping the undesirables in.

All in all, while the current guidelines may be stricter than this, I think an intelligent application of the existing policies already gives you what you want.

  • $\begingroup$ you start out by saying broadening scope will "destroy the existing community". huh? which one? TCS.SE? CS.SE? why? (not much explanations there..) "I think the community is doing an adequate job of retaining the audience it likes in and keeping the undesirables in." ... typo? think you meant undesirables out $\endgroup$ – vzn Aug 13 '12 at 14:45

1st, the good news. the site has many experts subscribing & signed up. thats a huge accomplishment and not easy to pull off. it has a high quality of content. it has indeed attracted many experts.

next, the bad news: the experts are not really engaged a lot on the site (a subjective observation after 0.5 yr, admittedly short, although not compared to the overall lifetime of the site), also indicated by decreasing questions even with increasing membership. there are a few high-engagement experts but there are many low-engagement experts.

by "experts", think of ppl that are highly qualified in TCS & which we would like to participate & hear their contributions but dont nec have high site rep. this could be quantified further with good statistics & analysis, but unfortunately it takes awhile to find statistics like this from current data.

so, the big question is, why is that?

imho one of the highest priorities of the site is to get high participation from experts but not merely in answering questions. at least imho it is a degeneration of the site purpose if the experts are active but only mainly to "shoot down" questions via negative votes, negative comments, constant reference to the FAQ/charter etc.-- that seems like "pushing the river"...

what do experts in the field like to talk about? what are their own questions?

at times seemingly theres an unstated/unspoken/mistaken belief/groupthink/folklore around here that poor questions scare away the experts from participating. however, there are many experts on here, and there are many that are not really participating that much, and personally, I doubt its because of poor question quality.

would like to see a charter that encourages higher participation esp by experts, decreases some strictness on questions, aims toward a high/increasing level of question volume. at least, if site participation is going down even as membership is going up, something is wrong with the current approach.

so what is on charter? any topics that the experts like to discuss, but possibly not expert level-questions on those topics. but yes, emphasis on expert level answers. all of which are discovered not a priori but in fact a posteriori through the voting system.

moreover to a large degree, and perhaps contrary to conventional wisdom, often the quality of a question cannot be judged immediately on seeing it. the quality of a question is discovered over time. especially with research & mathematics, questions initially that sound innocuous turn out to be deep, or questions that seem deep turn out to be innocuous.

unclosed questions, on significant TCS topics, lying around with no answers are harmless on this site, and serve as "search engine bait" for experts to find and answer/revisit later. note that votes can be changed over time on the same Q/A (ie one can change ones vote from up to down or down to up after time or revisions--key functionality there).

apparently mainly a large, healthy diversity of content on expert topics is what attracts experts & encourages participation. a dribble of new questions daily is not sufficient. its not interesting.

I say, lets figure out creative/colorful ways to grow question volume, which is the main driver of span/breadth/diversity of content, (to reverse the current dramatic decline even with increasing members!) without so much focus on supposed question quality (which is not as objectively measurable or perceivable as many here would imply, and maybe even an unattainable/illusory goal) and instead let the software sort it out via voting and tagging mechanisms.

why are many experts not posting much questions or answers on this site? there is also a pattern/tendency, imho, of high rep users mainly answering questions, but not asking many, and then perhaps even turning around and saying that question quality (by everyone else) is poor quality.

recall, low voted questions disappear from the main page quickly. its as if they dont even exist. so this stackexchange software is inherently designed to deal with high question volume & participation & may break down somewhat in its design with low question volume.

from some statistics the question volume is down to 50% of the initial beta period and the close ratio has doubled within a month even on the lower volume. so yeah, lets revisit the charter & figure why the overall formula doesnt seem to be working any more given new conditions (other CS beta site etc)

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    $\begingroup$ The reason why I don't often ask questions here is that my questions strike me either as incredibly technical, or amounting to asking others to solve my problems for me. When I do ask a question here, I tend to have come across it as something which is easy to separate out of the technical context (so there's a good chance someone else has looked at before) but is still motivated by the technical context (it is a piece of a larger puzzle). If I and others were to pose every question we had, this place would become so dry and precise that it would feel like lying on a bed of shattered glass. $\endgroup$ – Niel de Beaudrap Aug 9 '12 at 21:02
  • $\begingroup$ I accept your pov but think, no, most questions we have, many of them good ones, would be downvoted in this current environment. I argue that theres a systemic, cultural opposition to some reasonably good questions. theres too much obsession with putting too much effort into questions here. it goes against the basic design/rationale of stackexchange software. as I recall in one blog post one of the authors described it as a process of getting pearls from grains of sand. the oyster is stack exchange, the grains of sand are the questions, and the pearls are the great answers $\endgroup$ – vzn Aug 9 '12 at 21:52
  • $\begingroup$ To be fair, there is a question about how to modify our approach to answering questions so that there's space for questions further away from the cutting edge of research. (That is why Kaveh asked the question, and why there are multiple attempts to answer.) You may find that on topics which are slightly more obscure, such as quantum computing for example, clear and well defined questions which are soft or otherwise not research level get asked and are frequently answered. It could be that we must broaden our scope, but to maintain a high-quality forum, we depend on good questions. $\endgroup$ – Niel de Beaudrap Aug 9 '12 at 21:52
  • $\begingroup$ respectfully disagree $\endgroup$ – vzn Aug 9 '12 at 22:01
  • $\begingroup$ addendum. lots of evidence that TCS.se is somewhat at odds with SE dynamics that tries to encourage & is designed for high volume/participation. shog9, SE moderator & community coordinator, says its a wonder that TCS.se works due to its highly niche nature: "please let me be frank with you: this network - which is to say, the people who comprise it, not the organization funding it - cannot support a dozen sites like CSTheory, now or in the near future." $\endgroup$ – vzn Sep 5 '12 at 16:00
  • $\begingroup$ addendum. SE with all its numerous quality control mechanisms may tend to lead to an emergent behavior of restrictive communities. SE founder joel spolsky on encouraging community, spirit of friendliness and avoiding elitism across sites— esp see all the comments on that blog. also, re TCS small niche vs overarching SE goals of higher traffic, note aborted SE "battle of the sites" contest to encourage increasing traffic across sites $\endgroup$ – vzn Sep 5 '12 at 16:11
  • $\begingroup$ addendum, more on ideas for increasing question volume and participation by hi rep users in this msg on beta period progress incl suggestions by kaveh and suresh. ironically, the question volume may have dropped to levels seen around the same time as that old discussion... $\endgroup$ – vzn Sep 13 '12 at 3:20

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