$S^2$-bundles over 2-orbifolds
Geometric Topology
2013-04-10 v3
Abstract
Let be a closed 4-manifold with . Then is homotopy equivalent to either , or the total space of an orbifold bundle with general fibre over a 2-orbifold , or the total space of an -bundle over an aspherical surface. If there are at most two such bundle spaces with given action . The bundle space has the geometry (if ) or (if ), except when is orientable and is generated by involutions, in which case the action is unique and there is one non-geometric orbifold bundle.
Cite
@article{arxiv.1008.4186,
title = {$S^2$-bundles over 2-orbifolds},
author = {Jonathan A. Hillman},
journal= {arXiv preprint arXiv:1008.4186},
year = {2013}
}
Comments
We have completed the determination of which $S^2$-orbifold bundles are geometric, and also computed the second Wu class for each such manifold. Further minor changes have been made (principally to the section on surgery) in the second revision