{c}

A <topology> $\mathcal T$ on $X$ contains $\varnothing$ and $X$, is closed under arbitrary unions, and is closed under finite intersections. Its members are the <open sets>. A subset $F\subseteq X$ is <closed> precisely when $X\setminus F$ is open.

Solution

Past exam of the probability, statistics and options I course of the University of Oxford / 2010 / E / 1 / a / i / Solution

 Solution (source code)