In $\Bbb R^2$, is the interior of $\Bbb R^2 - \{(x,sin(1/x))|x>0\}$ itself? The curve is continuous on $(0,\infty)$ so its graph is closed, and hence the set is open. Moreover, its boundary is $\{(x,sin(1/x))|x>0\}$.
Am I correct?
In $\Bbb R^2$, is the interior of $\Bbb R^2 - \{(x,sin(1/x))|x>0\}$ itself? The curve is continuous on $(0,\infty)$ so its graph is closed, and hence the set is open. Moreover, its boundary is $\{(x,sin(1/x))|x>0\}$.
Am I correct?
The boundary of $$\Bbb R^2 - \{(x,sin(1/x))|x>0\}$$ is $$B=\{(x,sin(1/x))|x>0\}\cup (\{0\}\times [-1,1])$$
The interior is$$\Bbb R^2 - B$$