# answered on math overflow tag

I notice that a number of questions are "unanswered" because in a comment it is pointed out that said question is answered on MO. Could there be a tag "answered in MO" (or "Answered elsewhere" as suggested in the comments) that could be created so that one could add it to the question?

This is an old issue (see also this post and this discussion suggested in the comments) of course, but this seems implementable and useful since one could filter it out when browsing unanswered questions.

[a development which I remove as it upset the author of the question I mentioned.]

But I see now that apparently a lot of very active people of this site are not bothered by this situation, so I'll get back to cultivate my garden, as Candide said.

• I don't see how adding a "answered on MO" tag would make any difference. What can be done by that tag? Apr 14 at 10:46
• Apr 14 at 11:58
• @ArcticChar il would make a difference because, as written above, one could filter this tag, and exclude questions tagged "answered on MO"
– user145413
Apr 14 at 13:01
• I imagine that would be an argument for "answered elsewhere" tag. Apr 14 at 13:42
• @ArcticChar this alternative formulation is now added
– user145413
Apr 14 at 17:29
• It's not clear to me that the user who posted the "very nice example" was ever satisfied by the replies at MO, that is, I think that user would still consider the question to be unanswered. Apr 16 at 0:00
• My linked question about $\dim(R[T])$ was not answered on mathoverflow so far: The "answer" posted by darx answers a different question, and all others answers have been deleted. The "answer" by darx has 15 upvotes since people have found it interesting or useful, even when it does not answer my question. I don't want to delete the question from either sites because it has gained a lot of attraction (I don't care for reputation, @moderators make it CW if you want!). Apr 16 at 7:49
• @MartinBrandenburg I said it was answered in the comments, I should have corrected my sentence. What I called the answer was Ingo Blechschmidt's comments, and your conclusion that the next step was to read his notes.
– user145413
Apr 16 at 13:14
• @username Why should Ingo Blechschmidt's comment there be an answer to my question? It was just a remark that the Lombardi-Coquand-Definition of the Krull dimension is also useful in a different context. Apr 16 at 14:05
• @MartinBrandenburg I added an erratum. You ask a difficult question. An expert make a comment pointing at a nearby area where the objects you work with are used also. You acknowledge you could possibly be inspired by reading the material suggested. That's as good an answer as you can hope for, considering hundreds of professional mathematicians have looked at your question, without a suggestion.
– user145413
Apr 16 at 17:40
• You clearly have no idea what the question is about. Perhaps it is a better choice to not talk about it at all. Also, the number of upvotes a question gets is not related to "number of professional mathematicians" having looked at the question, even less to the number of professional mathematics who have really worked to find a solution for the question - maybe that number is just 5. Therefore it is still possible that there is a solution. Apr 16 at 18:50

While the idea is in principle reasonable, that's not a recommended use for tags on Stack Exchange. It would be a so-called "meta tag". A tag on Stack Exchange should describe the subject of the question, not the type of the question, and certainly not extrinsic aspects.

If you come across such a question your options include:

• send the questions towards removal via a flag to close,
• ignore the matter and hope somebody else will deal with it.

What we do not want to is maintain questions indefinitely here that are answered elsewhere.

• A few years ago, I did exactly what you suggested: included the answer posted in the comments, with attribution, and made the answer a community wiki, as I wasn't looking to attribute it to myself. I was asked by the then moderators not to do it.
– user145413
Apr 14 at 13:04
• That discussion is here. But if the times they are a'changing and it is now ok to do so, very good.
– user145413
Apr 14 at 13:26
• @username Just to express a personal preference: "send the questions towards removal via a flag to close" is, I think, the best alternative. If a question has been asked and answered elsewhere on the SE network, then it is (essentially by definition) off-topic here. When I see questions which have been cross-posted, my first impulse is to either delete the question here, or ping a moderator on the sister site to let them know. quid and/or the other moderators may feel differently.
– Xander Henderson Mod
Apr 14 at 14:20
• @XanderHenderson while I agree that this can make sense, especially for questions o marginal quality, I don't see why "if a question has been asked and answered elsewhere on the SE network, then it is (essentially by definition) off-topic here" holds. Especially as regards MO and math.se I think that's not the case, fundamentally there is overlap between the scopes of the sites. In addition MO is not really part of the network and they might leave at some point. Thus it makes sense to keep our own copy of question and answer.
– quid Mod
Apr 14 at 14:27
• @username first that happened on another site and is thus not relevant here, second, it seems it was about a different activity. I propose to post the actual text of the answer as an answer post with a reference.
– quid Mod
Apr 14 at 14:38
• My question is now -5, my best score! Does that mean I should delete it?
– user145413
Apr 14 at 17:21
• @username now it means that users are against your feature request.
– quid Mod
Apr 14 at 17:24
• @username "Does that mean I should delete it?" Absolutely no, haven't you seen how helpful quid's answer is? Apr 14 at 22:03
• In the first bullet, I think one should leave a comment too, on the MO post. Apr 14 at 22:07
• @Verónica The suggested options are either not efficient or whimsical. The first one is very time consuming and of debatable value: copying and pasting from MO is something a robot can do, but will take a human a lot of time. Putting a flag / tag doesn't take that much effort. The third option, flag, is favored by XanderHenderson, but not so much by Quid. (Incidentally I don't understand the "MO is not really part of the network" part but ignorance can be bliss, I don't need to understand this as it probably irrelevant to the question at hand).
– user145413
Apr 15 at 10:46
• @Verónica good point. In a related spirit, one might even ask the poster on MO to repost their answer rather than copy it.
– quid Mod
Apr 15 at 20:07
• @username you have a curious notion of "a lot of time". Anyway if the post is not worth that effort it likely can be closed, and deleted. On the last point, it means that MathOverflow is not owned by SE but by an independent incorporation of the same name. In particular, this entity can decide at any point in time to leave the SE network. The site would cease to exist here. They could host it elsewhere or even take it down I assume (of course mirrors would exist somewhere and can continue to exist due to the license but still).
– quid Mod
Apr 15 at 20:14