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    • CommentAuthorAndrea
    • CommentTimeApr 4th 2010

    We are all quite used to reading (or writing) a standard reply to discussion-y (or discussive) questions, which more or less reads: "Dear xxx, your question is very interesting but it does not have a clear answer and leads to discussion. Unfortunately StackExchange, the platform on which MathOverflow runs, is designed for precise questions with a definite answer, and is not very well suited for discussions. You may want to ask the same question in a forum or on a math blog."

    I'm starting to wonder whether this is actually true. I should make clear that I like the role that MathOverflow has for math questions, and I don't like very much long and vague discussions. Still, I think that StackExchange is quite a good platform for discussions and less so for questions with a definite answer.

    1) StackExchange is a good software for discussions. Indeed it is very easy to follow discussions here. We have favorite questions, feedback whenever someone anwsers or comments our questions and answers, and more important, every time there is an answer, the question is bumped on the top of the main page. All these tools make life easy to follow discussions, certainly more than a blog where everything is linear and long discussions immediately become cumbersome. One may argue that a forum has even better facilities (for instance, on a forum you can quote other people) but on the other hand on a forum there are fixed categories. On StackExchange we have multiple tags for each thread, which allow a finer classification.

    2) StackExchange is not a very good software for precise questions with definite answers. Of course, this is not literally true, as both MathOverflow and StackOverflow (at least) show. Still, it is annoying that discussions always get bumped at the top, and it seems that the only reason why the first page is not all about growing children or mathematical jokes is that moderators are patiently keeping track of these discussions and closing them after a while. Whenever a question has a really precise answer that only a specialist can give, most people just don't reply and the question soon fades into the second page and becomes forgotten.

    So I think we are really cheating when we write this standard advice. StackExchange IS good for discussions, as it is witnessed by the many active discussions on MathOverflow itself. So, what is the point of this post?

    For one, I think that it would be more honest to write that discussions are simply not welcome here. I do not see any technical issue with having discussions, other than flooding MathOverflow and hiding the most interesting math questions.

    More concretely, I wonder whether we can make some sensible feature request for StackExchange. For instance, one may want to assign to every question a weight which is more or less inversely proportional to the number of answers already received. The highest the weight, the more plausible you will find the question on top of the list. One may also want to take care of whether the question has an accepted answer.

    In this way questions with a few answers will be bumped often, and hopefully get eventually answered. This would discourage big-list questions and help those still waiting for answers. Note that this would be more effective than periodically bumping unanswered questions, since a question may very well have just one or two answers which are irrelevant.


    I do agree with point 2. However, I'd like to add another point.

    This site is generally pretty good for hard questions in algebraic geometry, but I've noticed that hard questions in other fields very often are left unanswered and with a low score. Mediocre questions in algebraic geometry often end up with more votes than much better posts from any given field (and I say this having asked a few mediocre questions in algebraic geometry =p). This effect combined with the number of popular soft-questios/big-lists very often makes it very frustrating to ask anything here at all. The first problem seems like it could be addressed by closing down discussion and big-list questions by moderators, but I'm at a loss on how to deal with the problem I mentioned.

    • CommentAuthorKevin Lin
    • CommentTimeApr 4th 2010

    fpqc, I think this is simply because there are probably more people on the site who do AG than other subjects.

    • CommentAuthorKevin Lin
    • CommentTimeApr 4th 2010

    Andrea: I had had similar thoughts at one point: see

    A bit later, I changed my mind: see

    I agree that the SE software would probably be reasonable for discussions. But I don't think that's the point. The point is that MO is meant for answering well-posed math questions. I think that if we allowed discussions, we'd run the risk of allowing the site to be overtaken by discussions and we'd possibly compromise the question/answer aspect of the site.

    I don't agree with your comment:

    Whenever a question has a really precise answer that only a specialist can give, most people just don't reply and the question soon fades into the second page and becomes forgotten.

    I don't think it gets forgotten. At the very least, the asker remembers it, the answerers remember it, and Google remembers it. And the next time someone in the world has that same question, they'll be able to find the answer.


    @Kevin: That is true, but it's a self-perpetuating problem. As I said, I can't think of any way to deal with it, but maybe someone else has some ideas.

    • CommentAuthorKevin Lin
    • CommentTimeApr 4th 2010

    fpqc: I don't think that's a problem per se. But I dunno -- Does "too much" AG somehow indirectly cause people in other fields to post less?

    • CommentAuthorMariano
    • CommentTimeApr 4th 2010

    The historical example of the arXiv is interesting. Not too long ago a few subject groups predominated significantly there, yet now this is no longer the case AFAICT.


    @Kevin Lin: The odds of getting an answer on a question are much lower for a lot of the subjects here, although I will admit that it has definitely gotten better. What would be interesting is if there were some way to invite people here in underrepresented subjects, if that could possibly work.


    I strongly disagree with point 1. I find it very hard to follow "discussions" on MO. I laid out my reasons in the thread to which Kevin linked.

    I dislike the idea that MO should become "All things to all mathematicians". It took me a while to come round to this, but I encourage anyone who thinks like this to read some of the discussions that Anton and I had here on meta to see what led me to change my mind.


    I'll state for the record that I think SE is not a good platform for true discussions and that I'm not saying so just because of some sort of intellectual momentum. Rather than reproduce my reasoning, I'll link to a few places where I think the reasoning was clearly laid out:

    @Andrew: If you don't mind my asking, what changed your mind? Was it discussion here on meta (if so, please link to the relevant threads if you can find them), or was it using MO itself?



    regarding the skew of subjects on the arxiv: I've heard actually that there is still a significant skew, matching the historical origins of the mathematics arxiv(s). There are some fun statistics at, but I'm not sure there's enough there to see what's going on in this regard.

    • CommentAuthorAndrea
    • CommentTimeApr 5th 2010

    It seems from the replies that I did not make my point very well. I'm NOT trying to encourage discussions on MO; indeed I'd like to see LESS such questions. But since I find StackExchange a good sofwtare for discussions (here not everyone agrees) I was wondering whether something can be done.

    The main point of my post, which noone addressed, is whether we can formulate a sensible feature request for StackExchange which would favor precise questions with respect to discussions. In particular I don't think a question should bump on top on each reply; instead I'd like to see some adjustment in such a way that questions with few answers stay on top more than the others.


    Let me try to make my argument clearer by making it more specific. I would love to have a discussion with Konrad Waldorf and Theo JF on the issues arising from Theo's question How, exactly, can I do that?

    If I post a comment in reply to Konrad's answer, Konrad gets a notification but Theo doesn't. If Konrad then posts a reply to that, neither myself nor Theo get notified! Plus, how do we cope with the limitations on formatting in comments? So maybe we should post answers instead, but then they aren't sorted and also make it confusing to someone interested in the answer to the original question.


    This is what the new @notification system will give us the flexibility to do.

    @Andrew: I don't claim that this is an ideal solution, but if your question is not rhetorical: you can post a community wiki answer labelled "This is for discussion with Theo and Konrad on...." and then the three of you can discuss away.

    I should make clear that I have absolutely no desire to have such a discussion on MO. I have better places to have such discussions (nLab/nForum spring to mind). My intention was purely to show that the current software cannot support such a discussion without either modification or subversion. (I'm not sure how the notification system works with community wiki answers, would we all get notified if we'd all edited it? Not that I particularly care about the answer to that, I just raise it to show that Pete's solution isn't necessarily a workable one). Of course, one could modify the system so that it did allow discussions, but then why reinvent the wheel? There are perfectly good forum software out there (hmm, that sentence doesn't read right ...) and it's much easier to simply install one of them than try to force SO into something that it isn't meant to be.

    • CommentAuthorMariano
    • CommentTimeApr 6th 2010

    Andrew, I'd suggest IRC. It surely is something like Web 0.4, but still works great :)


    (Please, I don't need any suggestions on how to have such a discussion! My point was that wherever is the right place, it isn't MO.)


    I think everybody here has agreed that there shouldn't be long discussions on MO. Not everybody has agreed about whether SE is any good for discussions. My understanding of Andrea's main point is this (Andrea, please correct this if it's wrong):

    Regardless of whether SE or MO are good for discussions, some people will believe it is, even if only temporarily. Should we do anything more than we're already doing to prevent people from trying to start discussion questions? If yes, what?

    I think the current approach of simply cultivating an atmosphere where discussion questions are discouraged is pretty good. I can't think of any software features that would help. Then again, maybe I'm just unimaginative. Any ideas?


    Just spotted this in Andrea's initial post (emphasis mine):

    One may argue that a forum has even better facilities (for instance, on a forum you can quote other people) but on the other hand on a forum there are fixed categories. On StackExchange we have multiple tags for each thread, which allow a finer classification.

    Nope. Forums don't have to have fixed categories. On the nForum, registered users can create their own categories if they don't like the ones that I've provided. Moreover, there are extensions to the software running that forum (and this) which allow for tags (I just haven't installed it on the nForum as it hasn't been asked for). There are also extensions that allow for community moderation and for voting on posts. So actually, while it's a lot of work to get SO to act like a forum, it's not that hard to get a forum to act like SO, so if you really want discussions, I suggest using a forum software.

    • CommentAuthorAndrea
    • CommentTimeApr 7th 2010

    Ehm... I DO NOT want discussions. I hoped I had made that clear...

    • CommentAuthorAndrea
    • CommentTimeApr 7th 2010

    I have filed a feature request on meta.stack-exchange, if you want to have a look. Even if this turns out to be irrelevant, maybe I can use this opportunity to get the minimum reputation on meta.stack-exchange to be able to vote up other requests.

    • CommentAuthorjonas
    • CommentTimeApr 18th 2010
    Mariano: good idea, shall we start a semi-official mathoverflow irc channel?
    • CommentAuthorKevin Lin
    • CommentTimeApr 18th 2010

    jonas: I think Anton/Scott tried to do that a while ago. I recall the channel being rather dead.

    • CommentAuthorjonas
    • CommentTimeApr 18th 2010 edited

    Kevin Lin: if even the staff wants one, they could make it the "official" chanel by mentioning it in the FAQ or some other site documentation and eventually it will get some users. Which network is it on? I don't want to start a second one.

    Update: according to it's on freenode.

    Any system where the entries are re-ordered from time to time is BAD for discussion.