User Ruben Verresen

42 votes

6 answers

3k views

Why is this combination of nearest-integer functions --- surprisingly --- continuous?

asked Dec 29, 2017 at 1:01

13 votes

1 answer

331 views

What is the significance of the $\mathbb Z_2 \times \mathbb Z_2$ subgroup of $SO(3)$?

asked Jun 12, 2017 at 14:09

12 votes

2 answers

5k views

How to find the Takagi decomposition of a symmetric (unitary) matrix?

asked Nov 22, 2016 at 18:16

11 votes

0 answers

302 views

Roots of partial sum of power series

asked Dec 31, 2020 at 1:50

8 votes

3 answers

695 views

Proving that the derivative always diverges faster than the original function

asked Jul 29, 2018 at 6:34

6 votes

0 answers

148 views

Is this a valid q-deformation of $SU(2)$ via the $SU(3)$ Lie algebra?

asked May 18, 2022 at 23:56

5 votes

0 answers

384 views

Finding zeros of function by integration: a novel relationship or not?

asked Jul 20, 2018 at 4:10

5 votes

2 answers

748 views

central extension of $\mathbb Z_3$ by $\mathbb Z_3$

asked Aug 22, 2017 at 17:14

4 votes

2 answers

208 views

How do I know whether the inverse function has a closed form?

asked Feb 5, 2019 at 16:20

4 votes

2 answers

782 views

Derivative of matrix exponential $\exp(A+xB)$ at $x=0$

asked Jan 30, 2020 at 2:30

4 votes

0 answers

88 views

Why is $\int_{0}^{2\pi} \int_0^{2\pi} \frac{\ln(21-4(\cos x+\cos y+\cos(x+y)))}{2\ln(9/2)}\frac{dx}{2\pi} \frac{dy}{2\pi}$ almost $1$?

asked May 20, 2022 at 23:46

3 votes

0 answers

189 views

Infinite product representation of $\sqrt{1-z}$

asked Dec 31, 2020 at 21:34

3 votes

0 answers

39 views

Eigenvalues of product of diagonal matrices and Sylvester-Hadamard matrices

asked Jul 5 at 5:01

3 votes

1 answer

318 views

Asymptotics of Hilbert transform from asymptotics of original function

asked Jul 28, 2018 at 23:30

3 votes

0 answers

58 views

Is this symmetric rational function known?

asked Jan 31, 2018 at 14:47

2 votes

1 answer

257 views

Second group cohomology group of compact Lie group is finite?

asked May 24, 2017 at 3:09

2 votes

1 answer

539 views

Given a matrix in $SO(4)$, how to find coefficients in basis of Lie algebra?

asked Jun 12, 2017 at 17:38

2 votes

3 answers

125 views

example of non-associativity in the physical universe?

asked Aug 14, 2018 at 20:42

1 vote

0 answers

32 views

continuity of factorization of differential operator

asked Feb 12, 2020 at 23:35

1 vote

0 answers

77 views

A curious interrelationship between distinct embeddings of $SO(M+1)$ into $SO(2M+1)$

asked May 6, 2020 at 21:11

1 vote

1 answer

110 views

Homotopy classes of maps which commute with complex conjugation

asked Sep 6, 2017 at 16:34

0 votes

2 answers

325 views

pullback of quotient map: injective on group cohomology?

asked Jul 10, 2019 at 15:04

0 votes

1 answer

50 views

Is this basis for complex matrices necessarily a unitary basis?

asked Mar 10 at 16:56

0 votes

2 answers

128 views

Trace condition implies matrix is unitary

asked Apr 14 at 21:25

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24 Questions

Why is this combination of nearest-integer functions --- surprisingly --- continuous?

What is the significance of the $\mathbb Z_2 \times \mathbb Z_2$ subgroup of $SO(3)$?

How to find the Takagi decomposition of a symmetric (unitary) matrix?

Roots of partial sum of power series

Proving that the derivative always diverges faster than the original function

Is this a valid q-deformation of $SU(2)$ via the $SU(3)$ Lie algebra?

Finding zeros of function by integration: a novel relationship or not?

central extension of $\mathbb Z_3$ by $\mathbb Z_3$

How do I know whether the inverse function has a closed form?

Derivative of matrix exponential $\exp(A+xB)$ at $x=0$

Why is $\int_{0}^{2\pi} \int_0^{2\pi} \frac{\ln(21-4(\cos x+\cos y+\cos(x+y)))}{2\ln(9/2)}\frac{dx}{2\pi} \frac{dy}{2\pi}$ almost $1$?

Infinite product representation of $\sqrt{1-z}$

Eigenvalues of product of diagonal matrices and Sylvester-Hadamard matrices

Asymptotics of Hilbert transform from asymptotics of original function

Is this symmetric rational function known?

Second group cohomology group of compact Lie group is finite?

Given a matrix in $SO(4)$, how to find coefficients in basis of Lie algebra?

example of non-associativity in the physical universe?

continuity of factorization of differential operator

A curious interrelationship between distinct embeddings of $SO(M+1)$ into $SO(2M+1)$

Homotopy classes of maps which commute with complex conjugation

pullback of quotient map: injective on group cohomology?

Is this basis for complex matrices necessarily a unitary basis?

Trace condition implies matrix is unitary