A subset $A$ is <compact> when every <open cover> of $A$ has a finite <subcover>. This may be stated using sets open in the ambient space or using the <subspace topology> on $A$; the definitions agree because every subspace-<open set> is the <intersection> of $A$ with an ambient-<open set>.

Solution

Past exam of the options I course of the University of Oxford / 2009 / E / E2 / a / i / Solution

 Solution (source code)