@François Dorais and @Martin Sleziak, thank you for your work on the data explorer queries. These could be very useful.
@Martin Sleziak: When I asked about detecting duplicate questions on Math.StackExchange and MathOverflow, I was thinking that we could take more systematic action on such posts. For example, we could notify the people asking such questions soon after they are posted, and even close or migrate the duplicate questions. The data explorer queries you and François Dorais gave above could be very useful for such a purpose, despite the approximate two day delay in the data available.
What do you, and others, think about taking such actions concerning these questions?
I am not sure about that. But I certainly agree with this: If you cross-post ... indicate clearly in all copies of the question that the question is cross posted (and link to other copies).
@quid: First of all, I want to congratulate you on the awesome and thorough job you have done with the tag 'topology'. I am sorry that I did not help much with that. I also wanted to ask you how you want to proceed now that the retagging of the tag 'topology' is approaching its final stretch. Do you still want to retag (nearly) all remaining questions which do not have either of the tags 'gn.general-topology', 'gt.geometric-topology', and 'at.algebraic-topology'?