User wlad - MathOverflow

16 votes

Famous examples of "serendipity" in 20th century mathematics

answered Apr 19, 2023 at 19:54

14 votes

Accepted

Is it possible to constructively prove that every quaternion has a square root?

answered Sep 20, 2019 at 0:35

9 votes

How would you have answered Richard Feynman's challenge?

answered Dec 6, 2021 at 12:36

9 votes

"Natural" undecidable problems not reducible to the halting problem

answered Dec 26, 2022 at 16:35

7 votes

Accepted

Resources on screw theory in classical mechanics

answered Oct 12, 2021 at 23:55

6 votes

Is it possible to constructively prove that every quaternion has a square root?

answered Sep 19, 2019 at 18:10

6 votes

Theorems with many distinct proofs

answered Aug 11, 2021 at 15:24

5 votes

What's "geometric algebra"?

answered Nov 24, 2021 at 17:00

4 votes

Golden ratio in contemporary mathematics

answered Sep 4, 2021 at 20:36

3 votes

Does there exist a polar decomposition of matrices over finite fields?

answered Jul 5, 2021 at 17:22

3 votes

Principled construction of the quaternions

answered Sep 25, 2019 at 15:22

3 votes

Accepted

3D similarities and quaternions?

answered Jun 8, 2020 at 9:45

3 votes

What fields can be used for an inner product space?

answered Feb 4, 2023 at 12:07

3 votes

What is the strength of “if $c≥0$ then $[0,c] = c·[0,1]$” in constructive math (w.r.t., LPO, WLPO, LLPO, etc.)?

answered Dec 13, 2022 at 21:09

2 votes

What structure is preserved by pseudo-homeomorphisms of pseudo-Euclidean spaces?

answered Jun 14, 2023 at 22:35

2 votes

Why do infinite-dimensional vector spaces usually have additional structure?

answered Aug 17, 2023 at 15:55

2 votes

Every square complex matrix is similar to a TRIDIAGONAL complex-symmetric matrix?

answered Mar 20 at 19:46

2 votes

Axiomatizing projective Hilbert spaces

answered Oct 20, 2021 at 21:48

2 votes

Accepted

Does Wilkinson's shift need to be discontinuous?

answered Mar 22, 2022 at 10:13

2 votes

Representing split-complex numbers as intervals and related compactification

answered Dec 14, 2021 at 12:55

2 votes

Example of nice isomorphism between Cl$_{p,q}(\mathbb R)$ and matrix algebras over $\mathbb R,\mathbb C,\mathbb H,\mathbb R^2,\mathbb C^2,\mathbb H^2$

answered Feb 9, 2022 at 11:24

1 vote

Most helpful math resources on the web

answered Sep 21, 2021 at 12:52

1 vote

Accepted

Algorithm for economically sampling method for Gaussian matrix product

answered Nov 11, 2020 at 12:03

1 vote

How to compute an indefinite generalisation of QR decomposition

answered Jan 17, 2021 at 9:50

1 vote

Accepted

If the direct sum of $L$ and $M$ has a pseudoinverse, then do $L$ and $M$ have pseudoinverses?

answered Mar 20, 2021 at 10:58

1 vote

Does the generalised directional derivative satisfy any version of the chain rule?

answered Apr 6, 2020 at 5:47

1 vote

Do infinitely nested radicals have any applications?

answered Apr 29, 2020 at 10:01

1 vote

Spectral properties of the LDL^T matrix factorization

answered Oct 27, 2022 at 15:14

1 vote

Axiomatizing projective Hilbert spaces

answered Jan 13, 2023 at 7:37

1 vote

Polar decomposition with respect to the nonstandard involution of quaternionic matrices?

answered Jul 13, 2023 at 18:33

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36 Answers

Famous examples of "serendipity" in 20th century mathematics

Is it possible to constructively prove that every quaternion has a square root?

How would you have answered Richard Feynman's challenge?

"Natural" undecidable problems not reducible to the halting problem

Resources on screw theory in classical mechanics

Is it possible to constructively prove that every quaternion has a square root?

Theorems with many distinct proofs

What's "geometric algebra"?

Golden ratio in contemporary mathematics

Does there exist a polar decomposition of matrices over finite fields?

Principled construction of the quaternions

3D similarities and quaternions?

What fields can be used for an inner product space?

What is the strength of “if $c≥0$ then $[0,c] = c·[0,1]$” in constructive math (w.r.t., LPO, WLPO, LLPO, etc.)?

What structure is preserved by pseudo-homeomorphisms of pseudo-Euclidean spaces?

Why do infinite-dimensional vector spaces usually have additional structure?

Every square complex matrix is similar to a TRIDIAGONAL complex-symmetric matrix?

Axiomatizing projective Hilbert spaces

Does Wilkinson's shift need to be discontinuous?

Representing split-complex numbers as intervals and related compactification

Example of nice isomorphism between Cl$_{p,q}(\mathbb R)$ and matrix algebras over $\mathbb R,\mathbb C,\mathbb H,\mathbb R^2,\mathbb C^2,\mathbb H^2$

Most helpful math resources on the web

Algorithm for economically sampling method for Gaussian matrix product

How to compute an indefinite generalisation of QR decomposition

If the direct sum of $L$ and $M$ has a pseudoinverse, then do $L$ and $M$ have pseudoinverses?

Does the generalised directional derivative satisfy any version of the chain rule?

Do infinitely nested radicals have any applications?

Spectral properties of the LDL^T matrix factorization

Axiomatizing projective Hilbert spaces

Polar decomposition with respect to the nonstandard involution of quaternionic matrices?