User Fiktor

78 votes

Accepted

Prove that $\prod_{k=1}^{n-1}\sin\frac{k \pi}{n} = \frac{n}{2^{n-1}}$

answered Oct 30, 2010 at 20:18

7 votes

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Proper Measurable subgroups of $\mathbb R$

answered Aug 4, 2010 at 11:46

6 votes

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Cutting the Cake Problem

answered Aug 14, 2010 at 12:02

6 votes

How do you show that $d\theta = \frac{x dy - y dx }{x^2 + y^2}$?

answered Oct 5, 2010 at 6:15

5 votes

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Continuous function satisfying $f^{k}(x)=f(x^k)$

answered Aug 13, 2010 at 19:14

5 votes

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Packing disjoint family of discs with radii $\tfrac{1}{2}, \tfrac{1}{3}, \tfrac{1}{4},\ldots$ inside the unit disc

answered Oct 3, 2010 at 15:40

5 votes

Accepted

A rational fraction with positive Taylor series

answered Sep 17, 2022 at 4:52

4 votes

Proof for the curl of a curl of a vector field

answered Jan 17, 2015 at 23:02

4 votes

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A unit speed differentiable curve which avoids a null set of directions

answered Sep 21, 2022 at 2:59

3 votes

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normalization factor for restricted density

answered Sep 18, 2010 at 22:31

3 votes

Behaviour of $u_{n}=\frac{u_{n-1}+u_{n-2}+n}{\gcd\left(u_{n-1},u_{n-2},n\right)}$

answered Sep 20, 2022 at 22:23

3 votes

How big are transitively reduced graphs?

answered Sep 30, 2010 at 13:25

2 votes

What do all the $k$-cycles in $S_n$ generate?

answered Aug 30, 2010 at 21:59

2 votes

The orthogonal complement of the space of row-null and column-null matrices

answered Sep 3, 2010 at 9:16

2 votes

If $\gcd(a,b) = 1$ and $a,b\mid x$ then $ab\mid x$.

answered Oct 29, 2010 at 4:52

2 votes

Limit of Gamma integrals

answered Sep 18, 2010 at 20:52

2 votes

Countability of disjoint intervals

answered Sep 20, 2010 at 8:28

2 votes

Accepted

Symmetric nash equilibrium

answered Aug 4, 2010 at 16:08

2 votes

Extending a principal connection form to an associated principal bundle

answered Sep 12, 2022 at 4:38

2 votes

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Vector space of bidirectional sequences indexed by $\mathbb{Z}$

answered Jan 17, 2015 at 23:19

2 votes

Accepted

Extended matrix function

answered Mar 6, 2014 at 23:39

2 votes

How to construct symmetric and positive definite $A,B,C$ such that $A+B+C=I$?

answered Sep 8, 2022 at 0:44

1 vote

Number of groups of a given order

answered Mar 8, 2014 at 19:39

1 vote

Sturm-Liouville Equation Problem

answered Sep 8, 2022 at 1:05

1 vote

Condition for tangency in 3D space

answered Sep 8, 2022 at 2:21

1 vote

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A Detail on a Proof of a Lemma to the Hahn Decomposition Theorem.

answered Sep 13, 2022 at 18:00

1 vote

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Is this Kullback-Leibler divergence between positive semidefinite matrices always well-defined?

answered Sep 21, 2022 at 4:07

1 vote

Accepted

Approximating a function using Bernstein polynomials: what if arbitrary support and dimension $>1$?

answered Sep 18, 2022 at 19:20

1 vote

stuck on computing points of ramification of a map of curves via sheaf of relative differentials

answered Oct 25, 2010 at 21:07

1 vote

Farkas’ lemma: purely algebraic intuition

answered Oct 29, 2010 at 19:56

Stack Exchange Network

35 Answers

Prove that $\prod_{k=1}^{n-1}\sin\frac{k \pi}{n} = \frac{n}{2^{n-1}}$

Proper Measurable subgroups of $\mathbb R$

Cutting the Cake Problem

How do you show that $d\theta = \frac{x dy - y dx }{x^2 + y^2}$?

Continuous function satisfying $f^{k}(x)=f(x^k)$

Packing disjoint family of discs with radii $\tfrac{1}{2}, \tfrac{1}{3}, \tfrac{1}{4},\ldots$ inside the unit disc

A rational fraction with positive Taylor series

Proof for the curl of a curl of a vector field

A unit speed differentiable curve which avoids a null set of directions

normalization factor for restricted density

Behaviour of $u_{n}=\frac{u_{n-1}+u_{n-2}+n}{\gcd\left(u_{n-1},u_{n-2},n\right)}$

How big are transitively reduced graphs?

What do all the $k$-cycles in $S_n$ generate?

The orthogonal complement of the space of row-null and column-null matrices

If $\gcd(a,b) = 1$ and $a,b\mid x$ then $ab\mid x$.

Limit of Gamma integrals

Countability of disjoint intervals

Symmetric nash equilibrium

Extending a principal connection form to an associated principal bundle

Vector space of bidirectional sequences indexed by $\mathbb{Z}$

Extended matrix function

How to construct symmetric and positive definite $A,B,C$ such that $A+B+C=I$?

Number of groups of a given order

Sturm-Liouville Equation Problem

Condition for tangency in 3D space

A Detail on a Proof of a Lemma to the Hahn Decomposition Theorem.

Is this Kullback-Leibler divergence between positive semidefinite matrices always well-defined?

Approximating a function using Bernstein polynomials: what if arbitrary support and dimension $>1$?

stuck on computing points of ramification of a map of curves via sheaf of relative differentials

Farkas’ lemma: purely algebraic intuition