在這篇論文中，我們將探討某些迭代函數系統（IFS）所形成之圖形的可逆性。
我們證明了一個全不連通（totally disconnected） 的 IFS
之吸引子（attractor） 是可逆的。
對於一般的情形，我們介紹支點條件（branch point condition）的概念，
並且證明了一個 IFS 的吸引子若滿足支點條件則為可逆。

Abstract
We discuss the invertibility of severval figures arising from iterated function
systems (IFS). We shall prove the attractor of a totally disconnected IFS is
invertible. More generally, we introduce a concept of branch point condition
and prove that the attractor of an IFS is invertible if it satisfies the branch
point condition.

Contents
1 Introduction 2
2 Invertibility and its application to
characterizing spheres among manifolds 3
3 Iterated function systems 6
4 Main results 11
References 18

References
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