Definition talk:Closure (Topology)

In this case, I can't see how there is merit for two separate pages. The derived set $H'$ of $H$ is defined as the set of all limit points of $H$. Comments? --abcxyz (talk) 01:11, 16 November 2012 (UTC)


 * Someone who does not connect those two facts may not realise the two things are the same till it's pointed out in a page demonstrating their equivalence. --prime mover (talk) 06:32, 16 November 2012 (UTC)


 * Last Tuesday, a second-year student told me he had learned that $\Z_n \cong \Z / n \Z$ (through an isomorphism theorem), to which statement I looked at him in utter confusion, incapable of comprehending any more why such a statement would require a proof... It's hard to imagine not knowing such things when one in fact does. --Lord_Farin (talk) 12:04, 16 November 2012 (UTC)