User David E Speyer - MathOverflow

178 votes

Most memorable titles

answered Oct 31, 2010 at 15:04

131 votes

Accepted

Why do primes dislike dividing the sum of all the preceding primes?

answered Feb 1, 2013 at 12:41

113 votes

Accepted

Invertible matrices of natural numbers are permutations... why?

answered Apr 18, 2011 at 14:25

102 votes

Accepted

Irreducibility of polynomials in two variables

answered Feb 3, 2010 at 23:25

88 votes

$\prod_{n=1}^{\infty} n^{\mu(n)}=\frac{1}{4 \pi ^2}$

answered Mar 12, 2013 at 15:14

84 votes

Accepted

Why could Mertens not prove the prime number theorem?

answered May 2, 2012 at 12:36

82 votes

Applications of the Chinese remainder theorem

answered Dec 29, 2009 at 11:47

80 votes

Conceptual reason why the sign of a permutation is well-defined?

answered Mar 8, 2022 at 17:44

76 votes

Open problems with monetary rewards

answered May 27, 2011 at 0:57

75 votes

When is the product of two ideals equal to their intersection?

answered Dec 13, 2010 at 14:14

72 votes

Accepted

Ideas for introducing Galois theory to advanced high school students

answered Dec 15, 2021 at 15:44

71 votes

Accepted

When can one continuously prescribe a unit vector orthogonal to a given orthonormal system?

answered Nov 6, 2018 at 14:39

70 votes

Accepted

Generating a finite group from elements in each conjugacy class

answered Jun 4, 2010 at 0:21

65 votes

Strengthening the induction hypothesis

answered Jul 13, 2010 at 14:01

61 votes

English reference for a result of Kronecker?

answered Jan 6, 2010 at 13:17

61 votes

Eigenvalues of matrix sums

answered Nov 5, 2009 at 14:09

60 votes

Applications of the Chinese remainder theorem

answered Dec 29, 2009 at 11:32

60 votes

Accepted

Computing $\prod_p(\frac{p^2-1}{p^2+1})$ without the zeta function?

answered May 30, 2014 at 19:06

57 votes

Accepted

What is the Hirzebruch-Riemann-Roch formula for the flag variety of a Lie algebra?

answered Jan 11, 2010 at 16:12

57 votes

What should be learned in a first serious schemes course?

answered Jun 17, 2010 at 15:01

55 votes

Are there infinitely many integer-valued polynomials dominated by $1.9^n$ on all of $\mathbb{N}$?

answered Aug 12, 2013 at 17:28

52 votes

Accepted

How to visualize Dirichlet’s unit theorem?

answered Aug 2, 2018 at 21:28

51 votes

Does the rational power series ring $\mathbb{Q}[[X]]$ embed as a ring into the field of real numbers?

answered Aug 20, 2022 at 20:50

51 votes

What should be learned in a first serious schemes course?

answered Jun 17, 2010 at 14:57

48 votes

Accepted

Tell me an algebraic integer that isn't an eigenvalue of the sum of two permutations

answered Mar 8, 2017 at 4:03

46 votes

Are there infinitely many integer-valued polynomials dominated by $1.9^n$ on all of $\mathbb{N}$?

answered Aug 26, 2013 at 16:23

46 votes

Accepted

Boundedness of sum of sin(sin(n))

answered Aug 5, 2024 at 11:49

44 votes

Accepted

(Short) Exact sequences with no commutative diagram between them

answered Feb 18, 2014 at 17:57

44 votes

How did Cole factor $2^{67}-1$ in 1903?

answered May 22, 2015 at 21:24

43 votes

Accepted

de Rham vs Dolbeault Cohomology

answered Apr 27, 2012 at 17:04

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1,542 Answers

Most memorable titles

Why do primes dislike dividing the sum of all the preceding primes?

Invertible matrices of natural numbers are permutations... why?

Irreducibility of polynomials in two variables

$\prod_{n=1}^{\infty} n^{\mu(n)}=\frac{1}{4 \pi ^2}$

Why could Mertens not prove the prime number theorem?

Applications of the Chinese remainder theorem

Conceptual reason why the sign of a permutation is well-defined?

Open problems with monetary rewards

When is the product of two ideals equal to their intersection?

Ideas for introducing Galois theory to advanced high school students

When can one continuously prescribe a unit vector orthogonal to a given orthonormal system?

Generating a finite group from elements in each conjugacy class

Strengthening the induction hypothesis

English reference for a result of Kronecker?

Eigenvalues of matrix sums

Applications of the Chinese remainder theorem

Computing $\prod_p(\frac{p^2-1}{p^2+1})$ without the zeta function?

What is the Hirzebruch-Riemann-Roch formula for the flag variety of a Lie algebra?

What should be learned in a first serious schemes course?

Are there infinitely many integer-valued polynomials dominated by $1.9^n$ on all of $\mathbb{N}$?

How to visualize Dirichlet’s unit theorem?

Does the rational power series ring $\mathbb{Q}[[X]]$ embed as a ring into the field of real numbers?

What should be learned in a first serious schemes course?

Tell me an algebraic integer that isn't an eigenvalue of the sum of two permutations

Are there infinitely many integer-valued polynomials dominated by $1.9^n$ on all of $\mathbb{N}$?

Boundedness of sum of sin(sin(n))

(Short) Exact sequences with no commutative diagram between them

How did Cole factor $2^{67}-1$ in 1903?

de Rham vs Dolbeault Cohomology