Transverse foliations of Seifert bundles and self homeomorphism of the circle
Transverse foliations of Seifert bundles and self homeomorphism of the circle
复制标题
Seifert丛的横向叶理和圆的自同胚
DOI:
10.1007/bf02566232
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发表时间:
1981
影响因子:
0.9
通讯作者:
W. Neumann
中科院分区:
文献类型:
--
作者:
D. Eisenbud;U. Hirsch;W. Neumann
In this paper we give criteria for a Seifert circle bundle over a compact surface to admit foliations whose leaves are all transverse to the fibers, and we discuss which foliations may be deformed to foliations of this type. Our criteria for transverse foliations, presented in Section 3, are simple numerical inequalities involving the Seifert pairs of the fibration and the euler number of the base (Theorems 3.1 to 3.4). They generalize criteria of Milnor [Mi] and Wood [W], who treat the case of locally trivial circle bundles with orientable total space (see also Sullivan [Su] for a higher dimensional generalization of Milnor and Wood). They are complete except for the case that the base is S 2, in which case we only have partial results (Theorems 3.3, 5.3). Our criteria are valid both for the case of CO foliations and, as we show in Section 4, for analytic foliations, hence also for any intermediate degree of smoothness. We reduce the geometric question of the existence of foliations to algebra in a way similar to that of Milnor and Wood. We let~ be the group of selfhomeomorphisms [: R--> R which are lifts of self-homeomorphisms of the circle. contains the group~+={f: R~ R [f monotonically increasing and f (r+ 1)= f (r)+ 1 for all r~ R} as a subgroup of index 2 (the" flip" t (r)=-r is a coset representative for the non-trivial coset of 9+ in 9). For each real number 3'we write sh (3")~~+ for the" shift" by% that is sh (3"): r,--~, r+ 3" for r~ R. It turns out that the problem of transversely foliating a Seifert fibered manifold M is equivalent to the problem of finding a homomorphism 7rl (M)~ which takes the class of a nonsingular fiber of M to the element sh (1)~+(Theorem 3.5). This in turn is equivalent to a problem of representating a certain product of conjugates of shifts as a product of a certain number of commutators in* The authors wish to express their gratitude to the SFB 40 and the mathematical institute of the University of Bonn, under whose roof most of the work of this paper was done. The first and last authors are also grateful for the partial support of the NSF.