Can you mention a set in $\displaystyle R^2$ which is neither open nor closed. Thanks
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Originally Posted by osodud Can you mention a set in $\displaystyle R^2$ which is neither open nor closed. Thanks Let's try a really simple one: $\displaystyle \{(x,0)\in\mathbb{R}^2\mid x\in \;]0,1[\}$
Originally Posted by osodud Can you mention a set in $\displaystyle R^2$ which is neither open nor closed. Thanks $\displaystyle [a,b[ \times ]c,d]$ , with $\displaystyle a,b,c,d \in \mathbb{R}$ and $\displaystyle a<b, c<d$ CB
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