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David E Speyer

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representation-theory

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14 Questions

Views Newest Activity Votes

votes

answers

views

Can squares of infinite area always cover a unit square?

Dec 21 '17 at 18:13 Yly 7,124

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. is a poor mathematician 61.7k

votes

answers

611

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. is a poor mathematician 61.7k

votes

answers

611

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

answer

291

views

Can extending a finite ground field make modules isomorphic?

abstract-algebra modules finite-fields

May 13 '13 at 13:57 David E Speyer 47.2k

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♦ 20.4k

votes

answers

193

views

Probability that an exam will have a perfect predictor

probability combinatorics

Dec 8 '16 at 22:26 Community♦ 1

votes

answers

169

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 20.9k

votes

answer

294

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

186

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 47.2k

votes

answer

167

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 47.2k

votes

answer

152

views

Interpolating between Krull-Schmidt and Jordan-Holder

group-theory

Jan 8 '13 at 21:57 Community♦ 1

votes

answers

422

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

182

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 896

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14 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?

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

Can extending a finite ground field make modules isomorphic?

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

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?

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