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charmd
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24 votes
4 answers
12k views

Is a convex function always continuous?

17 votes
2 answers
1k views

Function $f$ such that $|f(x)-f(y)| \ge \sqrt{|x-y|}$

15 votes
1 answer
398 views

Power series converging at $1$ with all derivatives zero

12 votes
0 answers
175 views

Is a product of derivatives still a derivative? [duplicate]

8 votes
3 answers
340 views

Symmetric strategy for 100 prisoners and a light bulb problem

8 votes
1 answer
241 views

Biggest convex set inside a concave unit ball

4 votes
1 answer
702 views

Image of a null set by a Hölder continuous function

3 votes
1 answer
151 views

Function with null integral around every point

3 votes
3 answers
276 views

Are $\mathcal{O}(n)$ and $\mathcal{SO}(n)$ isomorphic?

1 vote
2 answers
68 views

Sequence with bounded sums [closed]

1 vote
2 answers
62 views

Two functions, each the integral of the other

1 vote
1 answer
64 views

Compact planar set with positive area contains cartesian products

1 vote
0 answers
38 views

How are these sums called?

1 vote
1 answer
231 views

Even polynomial having multiple with odd coefficients

1 vote
3 answers
918 views

Average number of head streaks in $N$ coin tosses

0 votes
0 answers
645 views

About the symmetric multilinear maps