User jjcale

1 vote

Minimal polynomial of cos(π/n)

answered Apr 13, 2023 at 12:46

3 votes

Accepted

Is $k(A, B) = \text{Tr}[(A^{1/2} B A^{1/2})^{1/2}]$ a positive definite kernel?

answered Feb 21, 2023 at 9:58

2 votes

Vanishing periodizations $\sum_{k \in \mathbb Z} f(t+ak)$ of a function $f$ for different values of $a$ implies $f=0$?

answered Feb 20, 2023 at 14:24

0 votes

Why is addition of observables in quantum mechanics commutative?

answered Feb 19, 2023 at 14:58

3 votes

Vacuum vector and basis defined by anti-commuting operators

answered Apr 10, 2022 at 19:05

2 votes

Minimal polynomial in $\mathbb Z[x]$ of seventh degree with given roots

answered Oct 30, 2020 at 19:08

3 votes

Does there exist a continuous function of compact support with Fourier transform outside L^1?

answered May 1, 2012 at 16:54

14 votes

Examples of theorems with proofs that have dramatically improved over time

answered May 3, 2012 at 16:40

18 votes

Is the linear span of special orthogonal matrices equal to the whole space of $N\times N$ matrices?

answered Sep 11, 2018 at 19:17

3 votes

Accepted

An Optimization Problem with Complex Variables, regarding Eigenvalues of Circulant Matrices

answered Jun 24, 2018 at 20:32

7 votes

Accepted

Well known matrix inequality?

answered May 13, 2018 at 16:20

4 votes

Accepted

What are the possible eigenvalues of these matrices?

answered Mar 11, 2018 at 17:04

7 votes

What are the possible eigenvalues of these matrices?

answered Mar 5, 2018 at 18:37

4 votes

Accepted

A singular value-eigenvalue inequality

answered Dec 2, 2017 at 20:59

3 votes

Computation of a minimal polynomial

answered Sep 4, 2017 at 16:22

3 votes

Computation of a minimal polynomial

answered Sep 3, 2017 at 18:40

3 votes

Accepted

A simple but curious determinantal inequality

answered Jun 24, 2017 at 13:41

4 votes

Inequality with symmetric polynomials

answered Feb 20, 2017 at 19:02

3 votes

Accepted

A generalized log inequality for positive definite trace-one matrices

answered Feb 12, 2017 at 10:26

2 votes

Can there be a polymath project for mathematical physics?

answered Jan 28, 2017 at 10:10

1 vote

Accepted

Bounded operators $T: B(H)\to H$ whose Kernel is a Lie algebra

answered Jul 2, 2016 at 18:45

2 votes

Most helpful math resources on the web

answered Nov 16, 2011 at 19:39

1 vote

Accepted

Choi type matrix condition for completely positivity on a certain operator system spanned by some unitaries

answered May 26, 2016 at 19:47

5 votes

Accepted

How to prove this determinant is positive-II?

answered Feb 24, 2016 at 18:59

6 votes

How to prove this determinant is positive?

answered May 3, 2015 at 13:34

2 votes

How to solve such an optimization problem

answered Aug 31, 2014 at 12:19

0 votes

Does positivity preserve compactness?

answered Mar 6, 2014 at 18:41

14 votes

What is a good method to find random points on the n-sphere when n is large?

answered Jul 10, 2013 at 19:16

6 votes

Open problems in PDEs, dynamical systems, mathematical physics

answered Mar 20, 2013 at 22:18

5 votes

Accepted

on an inequality of Brezis-Lieb

answered Jan 23, 2013 at 19:46

Stack Exchange Network

41 Answers

Minimal polynomial of cos(π/n)

Is $k(A, B) = \text{Tr}[(A^{1/2} B A^{1/2})^{1/2}]$ a positive definite kernel?

Vanishing periodizations $\sum_{k \in \mathbb Z} f(t+ak)$ of a function $f$ for different values of $a$ implies $f=0$?

Why is addition of observables in quantum mechanics commutative?

Vacuum vector and basis defined by anti-commuting operators

Minimal polynomial in $\mathbb Z[x]$ of seventh degree with given roots

Does there exist a continuous function of compact support with Fourier transform outside L^1?

Examples of theorems with proofs that have dramatically improved over time

Is the linear span of special orthogonal matrices equal to the whole space of $N\times N$ matrices?

An Optimization Problem with Complex Variables, regarding Eigenvalues of Circulant Matrices

Well known matrix inequality?

What are the possible eigenvalues of these matrices?

What are the possible eigenvalues of these matrices?

A singular value-eigenvalue inequality

Computation of a minimal polynomial

Computation of a minimal polynomial

A simple but curious determinantal inequality

Inequality with symmetric polynomials

A generalized log inequality for positive definite trace-one matrices

Can there be a polymath project for mathematical physics?

Bounded operators $T: B(H)\to H$ whose Kernel is a Lie algebra

Most helpful math resources on the web

Choi type matrix condition for completely positivity on a certain operator system spanned by some unitaries

How to prove this determinant is positive-II?

How to prove this determinant is positive?

How to solve such an optimization problem

Does positivity preserve compactness?

What is a good method to find random points on the n-sphere when n is large?

Open problems in PDEs, dynamical systems, mathematical physics

on an inequality of Brezis-Lieb