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David E Speyer

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galois-theory
121/100 score
16/20 answers

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8 posts edited
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7,568 votes cast
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17 Questions

Votes Activity Newest Views
35
58
votes
5
answers
4k
views

Can squares of infinite area always cover a unit square?

real-analysis geometry tiling
Dec 21 '17 at 18:13 Yly 12.5k
26
36
votes
1
answer
4k
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
9
20
votes
4
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
5
17
votes
1
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
2
16
votes
2
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
3
15
votes
4
answers
1k
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
5
12
votes
2
answers
232
views

Probability that an exam will have a perfect predictor

probability combinatorics
Dec 8 '16 at 22:26 Community♦ 1
3
10
votes
2
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
4
10
votes
1
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
5
8
votes
2
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
1
8
votes
0
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
4
7
votes
1
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
2
7
votes
1
answer
179
views

Interpolating between Krull-Schmidt and Jordan-Holder

group-theory
Jan 8 '13 at 21:57 Community♦ 1
3
6
votes
2
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
1
5
votes
2
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
 
2
votes
1
answer
81
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
 
0
votes
4
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
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