The closures of $\{1/n\}$ and $\ZZ$ contain no interval, while $\QQ$ is dense in $\RR$.Suggest a slogan
In \(\RR\):
\(\theset{1/n\suchthat n\geq 1}\) and \(\ZZ\) are nowhere dense, since their closures \(\theset{0}\cup\theset{1/n\suchthat n\geq 1}\) and \(\ZZ\) contain no open interval;
\(\QQ\) and \(\ZZ\cup\qty{(a, b)\cap\QQ}\) for \(a<b\) are not nowhere dense, since their closures \(\RR\) and \(\ZZ\cup[a,b]\) contain the open interval \((a,b)\).
Give an example of a set that is not nowhere dense.