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Prove that the unit open ball in $\mathbb{R}^2$ cannot be expressed as a countable disjoint union of open rectangles. Open rectangles in $\mathbb{R}^2$ are subsets of the form $(a,b)\times(c,d)$.

Thanks a lot!

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    Welcome to math.SE, mitt! Please consider taking the time to read the [faq] to familiarise yourself with some of our common practices. In addition, [this page](http://meta.math.stackexchange.com/q/5020/8348) should give you a start at learning how to typeset mathematics here so that your posts say what you want them to, and also look good. As this question appears to be homework, please consider reading [this page](http://meta.math.stackexchange.com/q/1803/8348) for information about asking _effective_ homework-related questions. Cheers!2012-11-18
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    Mitt, as Arthur said you should show us what you have done and we can help you2012-11-18
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    https://math.stackexchange.com/q/1924277/94642017-08-10

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