This is my question
http://mathoverflow.net/questions/262039/central-properties-of-the-integers-mathbbz-over-other-structures-with-sumhttps://mathoverflow.net/questions/262039/central-properties-of-the-integers-mathbbz-over-other-structures-with-sum
I think the question is clear enough and it is easy to understand what I'm asking. The question is not easy, it is difficult, but this is not a good excuse to closed it or put in on-hold. It should be open because someone could answer it. I could be agreed on put it as community-wiki, but why have they closed it?