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Henno Brandsma
the Netherlands
http://at.yorku.ca/cgi-bin/bbqa
Dutch topologist, now working in other fields.
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Top Questions
66
votes
Non-homeomorphic spaces that have continuous bijections between them
gn.general-topology
big-list
examples
asked Jul 5, 2010 at 20:03
mathoverflow.net
9
votes
Relatively countably compact subsets without countably compact closure.
gn.general-topology
asked Jul 5, 2010 at 20:09
mathoverflow.net
Top Answers
104
Elementary proof that $\mathbb{R}^n$ is not homeomorphic to $\mathbb{R}^m$
math.stackexchange.com
97
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
92
How secure is Chrome storing a password?
security.stackexchange.com
83
Projection map being a closed map
math.stackexchange.com
72
Is $\mathbb R^3$ the square of some topological space?
mathoverflow.net
55
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
51
Show that the countable product of metric spaces is metrizable
math.stackexchange.com
47
Proof that product topology of subspace is same as induced product topology
math.stackexchange.com
33
Quick proofs of hard theorems
mathoverflow.net
31
Locally Constant Functions on Connected Spaces are Constant
math.stackexchange.com
30
Why do we need topological spaces?
math.stackexchange.com
28
What are the issues in modern set theory?
math.stackexchange.com
26
Continuous image of a locally connected space which is not locally connected
math.stackexchange.com
25
Perfect set without rationals
math.stackexchange.com
25
A topology that is finer than a metrizable topology is also metrizable?
math.stackexchange.com
24
What is the reason for the term "zero dimensional" in the context of topology?
math.stackexchange.com
24
Any open subset of $\Bbb R$ is a countable union of disjoint open intervals
math.stackexchange.com
23
Topology vs Borel sigma-algebra on a set $X$
math.stackexchange.com
23
No. of possible dense subsets of a metric space
math.stackexchange.com
22
Why is the lower limit topology not metrizable?
math.stackexchange.com
22
A quotient of a locally connected space is locally connected
math.stackexchange.com
21
Is every manifold a metric space?
math.stackexchange.com
21
$f$ is Continuous if and only if its Graph is Closed in $X \times Y$
math.stackexchange.com
21
Are the rationals minus a point homeomorphic to the rationals?
math.stackexchange.com
21
What is your favorite proof of Tychonoff's Theorem?
mathoverflow.net
21
Definitions of Baire first and second category sets
math.stackexchange.com
21
Make $2^8 + 2^{11} + 2^n$ a perfect square
math.stackexchange.com
20
Locally compact Hausdorff space that is not normal
mathoverflow.net
20
Proving that a Banach space is separable if its dual is separable
math.stackexchange.com
19
Can Cantor set be the zero set of a continuous function?
mathoverflow.net
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