# Math Help - Prove that G is open in space

1. ## Prove that G is open in space

Prove that G is open in space

2. ## Re: Prove that G is open in space

Take $x\in\overline{G\cap\overline A}$ and let $V$ a neighborhood of $x$. We have $G\cap \overline A\cap V\neq \emptyset$. Let $a \in G\cap \overline A\cap V$. Use the fact that $G\cap V$ is a neighborhood of $a$.