# Math Help - Set in R^2 which is neither open nor closed.

1. ## Set in R^2 which is neither open nor closed.

Can you mention a set in $R^2$ which is neither open nor closed.

Thanks

2. Originally Posted by osodud
Can you mention a set in $R^2$ which is neither open nor closed.

Thanks
Let's try a really simple one: $\{(x,0)\in\mathbb{R}^2\mid x\in \;]0,1[\}$

3. Originally Posted by osodud
Can you mention a set in $R^2$ which is neither open nor closed.

Thanks
$[a,b[ \times ]c,d]$ , with $a,b,c,d \in \mathbb{R}$ and $a

CB