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arXiv · 1909.08425

The geometric index and attractors of homeomorphisms of $\mathbb{R}^3$

H. Barge·J. J. Sánchez-Gabites
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Abstract

In this paper we focus on compacta $K \subseteq \mathbb{R}^3$ which possess a neighbourhood basis that consists of nested solid tori $T_i$. We call these sets toroidal. In \cite{hecyo1} we defined the genus of a toroidal set as a generalization of the classical notion of genus from knot theory. Here we introduce the self-geometric index of a toroidal set $K$, which captures how each torus $T_{i+1}$ winds inside the previous $T_i$. We use this index in conjunction with the genus to approach the problem of whether a toroidal set can be realized as an attractor for a flow or a homeomorphism of $\mathbb{R}^3$. We obtain a complete characterization of those that can be realized as attractors for flows and exhibit uncountable families of toroidal sets that cannot be realized as attractors for homeomorphisms.

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H. Barge, J. J. Sánchez-Gabites. 2019-09-18. The geometric index and attractors of homeomorphisms of $\mathbb{R}^3$. https://doi.org/10.1017/etds.2021.105

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