CASSON-TYPE INVARIANTS IN DIMENSION FOUR
CASSON-TYPE INVARIANTS IN DIMENSION FOUR
复制标题
维度四中的 CASSON 型不变量
DOI:
10.1090/fic/047/18
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发表时间:
2005
期刊:
影响因子:
--
通讯作者:
N. Saveliev
中科院分区:
文献类型:
--
作者:
Daniel Ruberman;N. Saveliev
This article surveys our ongoing project about the relationship between invariants extending the classical Rohlin invariant of homology spheres and those coming from 4–dimensional (Yang-Mills) gauge theory; it will appear in the Proceedings of the Fields-McMaster Conference on Geometry and Topology of Manifolds. We are mainly concerned with a special class of manifolds for which the two types of invariants are defined and can be compared. This class contains, in particular, manifolds having the homology of S 1 × S 3 . Rohlin’s theorem about the signature of closed smooth spin 4–manifolds gives rise to a mod–2 invariant of a homology S 1 × S 3 . On the gauge theoretic side, the invariant is obtained by counting flat connections on appropriate bundles. This count is inspired by Donaldson’s [13] count of anti-self-dual connections on SU(2) bundles; its flat analogue was first studied by Furuta and Ohta [21]. The main conjecture towards which this project is directed is that the Rohlin invariant and the gauge theoretic invariant coincide for homology S 1 × S 3 . The model for the whole discussion is Casson’s beautiful theorem relating his invariant (in its gauge theoretic manifestation as described by Taubes [48]) and Rohlin’s invariant of homology 3–spheres. We will discuss the implications of this conjecture for some classical problems in low-dimensional topology, and progress we have made towards proving the conjecture. This progress includes the verification of the conjecture in some special cases, a ‘surgery’ program for approaching the conjecture by expanding its scope to include a wider category of manifolds, and the verification of this expanded conjecture for homology 4–tori. Much of this material is contained in our three papers [36, 37, 38] but we have included a broader overview as well as some additional examples. Acknowledgments. We would like to thank Scott Baldridge for pointing out the manifolds described in Section 8, and Liviu Nicolaescu for his input on computing orientations of flat moduli spaces over these manifolds. We also