How should questions that are posted (by the same asker) on Math.SE and another Stack Exchange site be handled?
The general Stack Exchange policy is that multi-posting is strongly discouraged. On other sites where I participate, when a question is found to have been multi-posted, we close it on all but one site. The site is chosen by two criteria:
- try to pick the site where the question is most on-topic;
- avoid losing or migrating worthwhile answers.
This is not a written policy (for all I know, I'm the first to write it down explicitly), but it's generally followed on the computer-related sites with overlapping scopes (Stack Overflow, Super User, Server Fault, Unix & Linux, Ask Ubuntu, etc.). What this means in practice:
- If the question is unanswered everywhere, we close it as too localized on all but one site. (Too localized because having this extra copy of the question doesn't make the Internet a better place.)
- If the question is answered on only one site, we close it on all but this site.
- If the question has answers worth keeping on more than one site, we migrate to a chosen destination and merge there.
- If there are several candidate sites, we try to pick the one where the question is most on-topic, the one where it is most likely to get the best answers.
Example: This question was also posted on Computer Science. Following general Stack Exchange habits, if I'd seen it before it had been answered, I'd have flagged it for closure on Math, because it's a CS question, more on-topic on CS than on Math. If I'd seen it when it had an answer on Math but none on CS, I'd have closed it on CS. Now that it has answers on both, I'd have flagged it for migration from Math to CS. But I don't know if Math.SE adheres to the general Stack Exchange policy in this respect.
Does Mathematics adhere to the general policy? If not, how should we deal with questions that are posted on Mathematics and another Stack Exchange site?