User David Feldman

394 votes

115 answers

110k views

Not especially famous, long-open problems which anyone can understand

asked Jun 21, 2012 at 18:30

97 votes

19 answers

38k views

Collecting proofs that finite multiplicative subgroups of fields are cyclic

asked Feb 8, 2011 at 8:30

90 votes

17 answers

6k views

Important open problems that have already been reduced to a finite but infeasible amount of computation

asked Nov 11, 2012 at 18:19

66 votes

1 answer

4k views

(Approximately) bijective proof of $\zeta(2)=\pi^2/6$?

asked May 2, 2012 at 2:14

52 votes

8 answers

6k views

What are the external triumphs of matroid theory?

asked May 3, 2011 at 20:32

50 votes

1 answer

6k views

Does Godel's incompleteness theorem admit a converse?

asked Oct 22, 2011 at 6:49

49 votes

4 answers

6k views

If the Riemann Hypothesis fails, must it fail infinitely often?

asked Dec 22, 2010 at 20:37

45 votes

8 answers

6k views

What makes a theorem a "nullstellensatz."

asked Jan 21, 2011 at 6:38

39 votes

1 answer

1k views

Modeling question: how often does "the world's oldest person" die?

asked Feb 2, 2011 at 9:35

36 votes

3 answers

5k views

Mazur's unpublished manuscript on primes and knots?

asked Dec 13, 2010 at 19:32

36 votes

3 answers

10k views

The deep significance of the question of the Mandelbrot set's local connectedness?

asked May 1, 2012 at 22:03

27 votes

2 answers

891 views

Careless packing

asked Mar 6, 2012 at 4:39

27 votes

1 answer

2k views

A puzzling remark of Manin (ICM 1978)

asked Dec 24, 2010 at 7:27

26 votes

1 answer

2k views

Nontrivial circular arguments?

asked Jan 27, 2011 at 14:48

24 votes

12 answers

3k views

Constructions unique up to non-unique isomorphism

asked Jan 30, 2011 at 7:53

24 votes

1 answer

615 views

Permutations, stopping times, Bessel functions, hook formula and Robinson-Schensted

asked Dec 1, 2011 at 6:28

23 votes

1 answer

767 views

The Euler-Mascheroni constant and entropy

asked Feb 12, 2019 at 22:12

22 votes

1 answer

1k views

Concerning the rarity of provably transcendental real numbers

asked Mar 26, 2011 at 7:44

21 votes

3 answers

2k views

A particular combinatorial proof of Wilson's theorem

asked Feb 1, 2011 at 20:34

21 votes

10 answers

6k views

Not especially famous, long-open problems which higher mathematics beginners can understand

asked Jul 2, 2012 at 18:25

20 votes

1 answer

2k views

What are the generalizations of the 27 lines on a cubic surface?

asked Apr 11, 2012 at 4:12

20 votes

1 answer

888 views

Does the Fourier expansion of the j-function have any prime coefficients?

asked Nov 21, 2020 at 11:09

20 votes

1 answer

1k views

The square root of Wilson's theorem when $p\equiv 1 \mod 4$

asked Feb 24, 2018 at 5:26

20 votes

2 answers

2k views

Tennenbaum's Theorem and polynomials

asked Mar 4 at 1:21

19 votes

3 answers

2k views

Research level applications of "row rank = column rank"?

asked Feb 28, 2013 at 5:19

18 votes

3 answers

1k views

Games that never begin

asked Nov 12, 2012 at 7:04

18 votes

3 answers

1k views

An equivalence relation on group actions

asked Oct 25, 2012 at 21:30

16 votes

2 answers

952 views

Where and when did "transition to abstraction" courses start?

asked Jan 6, 2011 at 7:03

16 votes

1 answer

883 views

Hearing the 17 planar symmetry groups

asked Dec 16, 2010 at 21:41

16 votes

1 answer

654 views

Galois theory: Generalization of Abel’s Theorem? (Better version!)

asked Dec 9, 2010 at 23:58

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157 Questions

Not especially famous, long-open problems which anyone can understand

Collecting proofs that finite multiplicative subgroups of fields are cyclic

Important open problems that have already been reduced to a finite but infeasible amount of computation

(Approximately) bijective proof of $\zeta(2)=\pi^2/6$?

What are the external triumphs of matroid theory?

Does Godel's incompleteness theorem admit a converse?

If the Riemann Hypothesis fails, must it fail infinitely often?

What makes a theorem a "nullstellensatz."

Modeling question: how often does "the world's oldest person" die?

Mazur's unpublished manuscript on primes and knots?

The deep significance of the question of the Mandelbrot set's local connectedness?

Careless packing

A puzzling remark of Manin (ICM 1978)

Nontrivial circular arguments?

Constructions unique up to non-unique isomorphism

Permutations, stopping times, Bessel functions, hook formula and Robinson-Schensted

The Euler-Mascheroni constant and entropy

Concerning the rarity of provably transcendental real numbers

A particular combinatorial proof of Wilson's theorem

Not especially famous, long-open problems which higher mathematics beginners can understand

What are the generalizations of the 27 lines on a cubic surface?

Does the Fourier expansion of the j-function have any prime coefficients?

The square root of Wilson's theorem when $p\equiv 1 \mod 4$

Tennenbaum's Theorem and polynomials

Research level applications of "row rank = column rank"?

Games that never begin

An equivalence relation on group actions

Where and when did "transition to abstraction" courses start?

Hearing the 17 planar symmetry groups

Galois theory: Generalization of Abel’s Theorem? (Better version!)