Removing Isolated Zeroes by Homotopy
Abstract
Suppose that the inverse image of the zero vector by a continuous map has an isolated point . There is a local obstruction to removing this isolated zero by a small perturbation, generalizing the notion of index for vector fields, the case. The existence of a continuous map which approximates but is nonvanishing near is equivalent to a topological property we call "locally inessential," and for dimensions , where is trivial, every isolated zero is locally inessential. We consider the problem of constructing such an approximation , and show that there exists a continuous homotopy from to through locally nonvanishing maps. If is a semialgebraic map, then there exists such a homotopy which is also semialgebraic. For and real analytic with a locally inessential isolated zero, there exists a H\"older continuous homotopy which, for , is real analytic and nonvanishing. The existence of a smooth homotopy, given a smooth map , is stated as an open question.
Cite
@article{arxiv.1712.01787,
title = {Removing Isolated Zeroes by Homotopy},
author = {Adam Coffman and Jiří Lebl},
journal= {arXiv preprint arXiv:1712.01787},
year = {2020}
}
Comments
to appear in Topological Methods in Nonlinear Analysis