Stack Exchange

Henno Brandsma

the Netherlands

http://at.yorku.ca/cgi-bin/bbqa

Dutch topologist, now working in other fields.
top accounts reputation activity favorites subscriptions
Top Questions
Top Answers
83
How secure is Chrome storing a password?
security.stackexchange.com

76
Elementary proof that $\mathbb{R}^n$ is not homeomorphic to $\mathbb{R}^m$
math.stackexchange.com

62
A map is continuous if and only if for every set, the image of closure is contained in the closure of image
math.stackexchange.com

51
Projection map being a closed map
math.stackexchange.com

47
Is $\mathbb R^3$ the square of some topological space?
mathoverflow.net

41
Prove $\limsup\limits_{n \to \infty} (a_n+b_n) \le \limsup\limits_{n \to \infty} a_n + \limsup\limits_{n \to \infty} b_n$
math.stackexchange.com

32
Quick proofs of hard theorems
mathoverflow.net

31
Show that the countable product of metric spaces is metrizable
math.stackexchange.com

24
What are the issues in modern set theory?
math.stackexchange.com

23
No. of possible dense subsets of a metric space
math.stackexchange.com

20
Proof that product topology of subspace is same as induced product topology
math.stackexchange.com

20
Perfect set without rationals
math.stackexchange.com

19
Make $2^8 + 2^{11} + 2^n$ a perfect square
math.stackexchange.com

19
Can Cantor set be the zero set of a continuous function?
mathoverflow.net

18
What is your favorite proof of Tychonoff's Theorem?
mathoverflow.net

18
Are the rationals minus a point homeomorphic to the rationals?
math.stackexchange.com

17
Any open subset of $\Bbb R$ is a at most countable union of disjoint open intervals. [Collecting Proofs]
math.stackexchange.com

17
Is every manifold a metric space?
math.stackexchange.com

17
Why is PuTTYgen-created RSA public exponent(e) not in {3,17,65537}?
crypto.stackexchange.com

16
How many orders of infinity are there?
mathoverflow.net

16
Why don't we define neighbourhoods to be open sets?
math.stackexchange.com

16
The closed graph theorem in topology
math.stackexchange.com

15
What's going on with “compact implies sequentially compact”?
math.stackexchange.com

15
Is this statement true: a set is open if every point has a closed ball contained inside of the set
math.stackexchange.com

15
Countability of a Totally Ordered Set
math.stackexchange.com

15
Are nets and filters useful in geometry and topology?
mathoverflow.net

15
Discrete subspaces of Hausdorff spaces
mathoverflow.net

15
Locally compact Hausdorff space that is not normal
mathoverflow.net

15
What are interesting families of subsets of a given set?
mathoverflow.net

14
Sum of a Series With Denominators of the form $(2^i) (3^j)(5^k)$
math.stackexchange.com

1 2 3 4 5 … 10