Return to Revisions

2 of 2

replaced http://mathoverflow.net/ with https://mathoverflow.net/

edited Apr 13, 2017 at 12:58

1
2
3

The category of groupoids as a categorification of the ring of rational numbers. See this MO question and this n-category cafe post.

answered Oct 26, 2010 at 11:28

12.1k
2
79
112