| | AMCA: On the exact sequence associated to a fibration of 2-groupoids by Enrico Vitale (Site not responding. Last check: 2007-08-19) |
 | | One of the basic construction in algebraic topology is the homotopy long exact sequence of groups and pointed sets associated, for each point of the domain, to a Hurewicz fibration between two topological spaces. |
 | | Recently, Hardie, Kamps and Kieboom have shown that, up to the dimension 2, this exact sequence is a special case of a 9-term exact sequence associated to a fibration of bigroupoids. |
 | | Roughly speaking, the idea is the following : Brown associates a 6-term exact sequence of groups and pointed sets to a fibration of groupoids ; since a 2-groupoid is to be thought as a higher dimensional groupoid, we have to associate a sequence of "higher dimensional" groups and pointed sets to a fibration of 2-groupoids. |
| at.yorku.ca /c/a/e/q/15.htm (342 words) |