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arXiv · 1204.1301

Common zeros of inward vector fields on surfaces

Morris W. Hirsch
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Abstract

A vector field X on a manifold M with possibly nonempty boundary is inward if it generates a unique local semiflow $Φ^X$. A compact relatively open set K in the zero set of X is a block. The Poincaré-Hopf index is generalized to an index for blocks that may meet the boundary. A block with nonzero index is essential. Let X, Y be inward $C^1$ vector fields on surface M such that $[X,Y]\wedge X=0$ and let K be an essential block of zeros for X. Among the main results are that Y has a zero in K if X and $Y$ are analytic, or Y is $C^2$ and $Φ^Y$ preserves area. Applications are made to actions of Lie algebras and groups.

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Morris W. Hirsch. 2012-04-27. Common zeros of inward vector fields on surfaces. https://arxiv.org/abs/1204.1301

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