- #1
Mandelbroth
- 611
- 24
A friend gave me this to prove as part of an ongoing "game." I'm having a serious amount of difficulty with it, and I don't know what I need to do.
"Prove the following:
If ##U\subset\mathbb{R}^n## is open, ##A\subset U## is homeomorphic to ##S^{n-1}##, and ##\varphi:U\to\mathbb{R}^n## is a continuous bijection from ##U## to ##\mathbb{R}^n##, then ##\varphi(\operatorname{int} A)=\operatorname{int} \varphi(A)##."2. Relevant [strike]equations[/strike] lemma
My friend said that I "might" need to know that "if ##B\subset\mathbb{R}^n## is homeomorphic to ##D^n=\left\{x\in\mathbb{R}^n : |x|\leq 1\right\}##, then ##\mathbb{R}^n\setminus B## is connected."
Here, the ##|x|## means ##\displaystyle \sqrt{\sum_{i=1}^n x_i^2}##.
I'm ashamed to say that I don't know where to start on this one. From the lemma that I "might" need, I know that ##\mathbb{R}^n\setminus \operatorname{int} A## is connected, but I don't know what this implies or how this gets me anywhere.
I'm really confused. I'd really appreciate any help anyone can give me.
Homework Statement
"Prove the following:
If ##U\subset\mathbb{R}^n## is open, ##A\subset U## is homeomorphic to ##S^{n-1}##, and ##\varphi:U\to\mathbb{R}^n## is a continuous bijection from ##U## to ##\mathbb{R}^n##, then ##\varphi(\operatorname{int} A)=\operatorname{int} \varphi(A)##."2. Relevant [strike]equations[/strike] lemma
My friend said that I "might" need to know that "if ##B\subset\mathbb{R}^n## is homeomorphic to ##D^n=\left\{x\in\mathbb{R}^n : |x|\leq 1\right\}##, then ##\mathbb{R}^n\setminus B## is connected."
Here, the ##|x|## means ##\displaystyle \sqrt{\sum_{i=1}^n x_i^2}##.
The Attempt at a Solution
I'm ashamed to say that I don't know where to start on this one. From the lemma that I "might" need, I know that ##\mathbb{R}^n\setminus \operatorname{int} A## is connected, but I don't know what this implies or how this gets me anywhere.
I'm really confused. I'd really appreciate any help anyone can give me.