8
$\begingroup$

If $A\subset B$ and $B$ is a metric space. What is the difference between "$A$ open subset of $B$" and "$A$ open relative to $B$"?

  • 6
    A open relative to B is often used to express the fact that A is open in the subspace topology http://en.wikipedia.org/wiki/Subspace_topology This would howerver require a slightly different setting than you described - you would need a larger space which contains B.2011-07-17

3 Answers 3