Got a PhD in topology in 98, now a cryptographer.
21 A map is continuous if and only if for every set, the image of closure is contained in the closure of image Feb 28 '12
19 What are the issues in modern set theory? Mar 3 '11
18 Projection map being a closed map Feb 19 '11
15 Countability of a Totally Ordered Set Jan 24
14 Perfect set without rationals Dec 12 '10