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Cantor Sets and Topological Entropy for Set-valued Functions on Countable Domains

James Kelly ⟨james.kelly@cnu.edu⟩

Abstract:

We characterize when an inverse limit of a set-valued function is a Cantor set. Given a set-valued function $F\colon X\to 2^X$, we define the set $D(F)=\bigcap_{n=1}^\infty F^n(X)$. It is known that $\varprojlim F=\varprojlim F _{D(F)}$, so we only need to consider the $F _{D(F)}$. When $D(F)$ is finite, $\varprojlim F$ is a shift of finite type, so we focus on the case where $D(F)$ is infinite, and we give a characterization for $\varprojlim F$ to be a Cantor set for this context. We go on to examine the entropy of a set-valued function on a countable domain and how that relates to the inverse limit being a Cantor set.

This includes joint work with L. Alvin and S. Greenwood.

Status: Accepted

Collection: Continuum Theory

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