Floer homology and the symplectic isotopy problem
Floer homology and the symplectic isotopy problem
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弗洛尔同源性和辛同位素问题
DOI:
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发表时间:
1997
期刊:
影响因子:
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通讯作者:
P. Seidel
中科院分区:
文献类型:
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作者:
P. Seidel
The symplectic isotopy problem is a question about automorphisms of a compact symplectic manifold. It asks whether the relation of symplectic isotopy between such automorphism is finer than the relation of diffeotopy (smooth isotopy). The principal result of this thesis is that there are symplectic manifolds for which the answer is positive; in fact, a large class of symplectic four-manifolds is shown to have this property. This result is the consequence of the study of a special class of symplectic automorphisms, called generalized Dehn twists. The hard part of studying the symplectic isotopy problem is how to prove that two given symplectic automorphisms are not symplectically isotopic. Symplectic Floer homology theory assigns a ‘homology group’ to any symplectic automorphism. These groups are invariant under symplectic isotopy, hence an obvious candidate for the task. While there is no general procedure for computing the Floer homology groups, it turns out that this is feasible for generalized Dehn twists. The computation involves an extension of the functorial structure of the Floer homology groups: we introduce homomorphisms induced by certain symplectic fibrations with singularities. Then we use the fact that generalized Dehn twists appear as monodromy maps of such fibrations. These induced maps on Floer homology groups may be of interest independently of their contribution to the symplectic isotopy problem. The thesis is divided into three parts: the first part presents the symplectic isotopy problem, introduces generalized Dehn twists, and explains the consequences of the determination of their Floer homology groups. The second part is devoted to Floer homology; its main focus are the new induced maps. The final part describes the computation of the Floer homology groups of a generalized Dehn twist.