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arXiv math/9912087math.GT
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Seifert纤维空间的正图

Positive diagrams for Seifert fibered spaces

John Hempel

摘要:

一个3-流形M的Heegaard图是一个闭的定向曲面S和S中的一对(X,Y)紧致1-流形,它们的分支作为M的Heegaard分裂两边的2-柄的附着曲线。如果X和Y可以定向,使得在它们相交的每个点p处的相交数<X,Y>_p = +1,则该图是正的。每一个(紧的,可定向的)3-流形都可以用一个正图来表示,但这一点的论证表明,一个正图的最小亏格phg(M)可能比所有图中的最小亏格hg(M)大得多。本文研究了一类可定向基上的闭可定向Seifert流形的这种情况。我们证明了对于大多数phg(M)不大于hg(M)+2的流形,phg(M)= hg(M).当最小亏格分裂是水平的时,确定了phg(M)> hg(M)的情况并出现.这些论点提供了另一种证据,将这些与垂直分裂区分开来。

英文摘要:

A Heegaard diagram for a 3-manifold M is a closed, oriented surface S together with a pair (X, Y) of compact 1-manifolds in S whose components serve as attaching curves for the 2-handles of the two sides of a Heegaard splitting for M. The diagram is positive if X and Y can be oriented so that the intersection number <X,Y>_p = +1 at each point p in their intersection. Every (compact, orientable) 3-manifold can be represented by a positive diagram, but the argument for this suggests that the minimal genus, phg(M), for a positive diagram may be much larger than the minimal genus,hg(M), among all diagrams. This paper investigates this situation for the class of closed orientable Seifert manifolds over an orientable base. We show that phg(M) = hg(M) for most of these manifolds with phg(M) never more than hg(M)+2. The cases phg(M) > hg(M) are determined and occur when the minimal genus splitting is horizontal. The arguments provide an alternate proof distinguishing these from vertical splittings.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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