The points $(n,0)$ belong to the indicated <subset> for every positive integer $n$. They form an <unbounded> <sequence>, so this <metric space> is not <bounded>. Therefore \b[it is not <compact>]. Shrinking the vertical width does not bound its horizontal extent.

Solution

Past exam of the metric spaces and complex analysis course of the University of Oxford / 2015 / 1 / c / v / Solution

 Solution (source code)