Dienstag, 29. April 2008

Questions on 2-covers



The following may well have been talked about by John in his lectures but I didn’t see it explicitly there, so I’ll ask.



Since at level 1, we have





A Galois connection between subgroups of the fundamental group π 1 (X) and path-connected covering spaces of X for path-connected X. A universal covering space is simply connected.





should we not expect a level 0 analogue:





A ‘connection’ between subsets of the set of connected components π 0 (X) and covering spaces of X whose locally constant fibres are either empty or {*}?





This puts these latter ‘covering spaces’ into correspondence with the poset of subsets of π 0 (X), so that the universal covering space with truth valued fibres is the empty set.



So do we have then:





A Galois 2-connection between sub-2-groups of the fundamental 2-group π 2 (X) and path-connected 2-covering spaces (with groupoid fibres) of X for path-connected X, a universal 2-covering space being 2-connected?





So, if we think of a nice space with nontrivial first and second homotopy, say the loop space of the 2-sphere, do we have a correspondence between 2-covering spaces and sub-2-groups of its fundamental 2-group? And is there a universal 2-connected 2-cover with 1- and 2-homotopy killed off?



0 Kommentare:

Kommentar veröffentlichen

Abonnieren Kommentare zum Post [Atom]

<< Startseite