Network profile

David E Speyer

Reputation

53,090

53.1k
46.9k
40.6k

2018
2019
2020
2021

Next tag badge

galois-theory

121/100 score

16/20 answers

Badges

156

240

Newest

Nice Answer

Next badge

25/50

Impact

8 posts edited

6 helpful flags

7,568 votes cast

17 Questions

Votes Activity Newest Views

votes

answers

views

Can squares of infinite area always cover a unit square?

Dec 21 '17 at 18:13 Yly 12.5k

votes

answer

views

How to compute rational or integer points on elliptic curves

reference-request diophantine-equations math-software elliptic-curves faq

Nov 2 '17 at 14:13 J. M. isn't a mathematician 68.7k

votes

answers

658

views

Why do siamese magic squares have real eigenvalues, symmetric around zero?

linear-algebra eigenvalues-eigenvectors recreational-mathematics magic-square

Jul 11 '15 at 19:56 J. M. isn't a mathematician 68.7k

votes

answer

342

views

Can extending a finite ground field make modules isomorphic?

abstract-algebra modules finite-fields

May 13 '13 at 13:57 David E Speyer 53.1k

votes

answers

648

views

Writing a group element as $ghg^{-1} h^{-1}$ and as $g^2 h^2$

abstract-algebra group-theory finite-groups representation-theory alternative-proof

Jul 21 '13 at 8:02 Community♦ 1

votes

answers

views

If a finite group $G$ is solvable, is $[G,G]$ nilpotent?

group-theory finite-groups solvable-groups

Feb 11 '13 at 3:07 Alexander Gruber♦ 25.7k

votes

answers

232

views

Probability that an exam will have a perfect predictor

probability combinatorics

Dec 8 '16 at 22:26 Community♦ 1

votes

answers

175

views

$AB=z \mathrm{Id}_n$ implies $z^m BA = z^{m+1} \mathrm{Id}_n$ for what $m$?

matrices algebraic-geometry commutative-algebra

Aug 7 '14 at 23:59 Geoff Robinson 21.9k

votes

answer

318

views

Covering a group with the conjugates of two subgroups related by an automorphism

group-theory finite-groups

Jun 14 '13 at 12:27 Community♦ 1

votes

answers

211

views

Simplest proof/greatest generality in which $|R/(\det A) R| = |R^n/A R^n|$

abstract-algebra commutative-algebra determinant

Oct 12 '19 at 20:21 Maxime Ramzi 38.3k

votes

answers

266

views

Slick proof that Coxeter groups $H_3$ and $H_4$ are finite?

finite-groups polyhedra coxeter-groups

Feb 9 '17 at 15:27 David E Speyer 53.1k

votes

answer

177

views

When does this matrix have an integral square root?

linear-algebra number-theory graph-theory

Apr 8 '14 at 13:45 David E Speyer 53.1k

votes

answer

179

views

Interpolating between Krull-Schmidt and Jordan-Holder

group-theory

Jan 8 '13 at 21:57 Community♦ 1

votes

answers

527

views

What happens to geodesic curvature under the Gauss map?

differential-geometry surfaces curvature geodesic

Apr 2 '15 at 13:04 Community♦ 1

votes

answers

131

views

$ab+ac+bc \equiv 1 \bmod abc$ or “easy chinese remainder theorem problems”

number-theory elementary-number-theory diophantine-equations chinese-remainder-theorem

Sep 24 '19 at 18:35 David E Speyer 53.1k

votes

answer

views

Is an ideal where all elements have $x^m=0$ nilpotent?

noncommutative-algebra nilpotence

Jan 28 '20 at 16:29 Daniel Schepler 13.8k

votes

answers

228

views

Why does the slope of a smooth simple closed curve have winding number one?

multivariable-calculus differential-topology winding-number

Aug 11 '16 at 16:43 Hulkster 1

Stack Exchange Network

current community

your communities

more stack exchange communities

Next badge

17 Questions

Can squares of infinite area always cover a unit square?

How to compute rational or integer points on elliptic curves

Why do siamese magic squares have real eigenvalues, symmetric around zero?

Can extending a finite ground field make modules isomorphic?

Writing a group element as $ghg^{-1} h^{-1}$ and as $g^2 h^2$

If a finite group $G$ is solvable, is $[G,G]$ nilpotent?

Probability that an exam will have a perfect predictor

$AB=z \mathrm{Id}_n$ implies $z^m BA = z^{m+1} \mathrm{Id}_n$ for what $m$?

Covering a group with the conjugates of two subgroups related by an automorphism

Simplest proof/greatest generality in which $|R/(\det A) R| = |R^n/A R^n|$

Slick proof that Coxeter groups $H_3$ and $H_4$ are finite?

When does this matrix have an integral square root?

Interpolating between Krull-Schmidt and Jordan-Holder

What happens to geodesic curvature under the Gauss map?

$ab+ac+bc \equiv 1 \bmod abc$ or “easy chinese remainder theorem problems”

Is an ideal where all elements have $x^m=0$ nilpotent?

Why does the slope of a smooth simple closed curve have winding number one?