Stefan Kohl's user avatar
Stefan Kohl's user avatar
Stefan Kohl's user avatar
Stefan Kohl
Moderator
  • Member for 11 years, 4 months
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14 votes
2 answers
1k views

Can a group generated by its involutions, the product of every two of which has order a power of 2, have an element of odd order?

13 votes
2 answers
796 views

Sums of reciprocals of prime numbers: $p \equiv a \!\! \mod m$ vs. $p \equiv b \!\! \mod m$

12 votes
0 answers
537 views

Possible orders of products of 2 involutions which interchange disjoint residue classes of the integers

12 votes
0 answers
699 views

Solving a set of equations in a finite symmetric group

11 votes
1 answer
496 views

Numbers of distinct products obtained by permuting 3 factors

11 votes
2 answers
700 views

How small can maximal subgroups be?

10 votes
0 answers
170 views

Number of matrices with 'small' entries in integer matrix groups

9 votes
2 answers
525 views

Sign of permutation induced by modular exponentiation

9 votes
1 answer
260 views

Cover of the positive real numbers by intervals

9 votes
0 answers
395 views

'Almost-isomorphic' groups

9 votes
1 answer
223 views

Is it always possible to "encircle" exactly $n$ points in an infinite subset of $\mathbb{R}^d$ without limit points?

8 votes
3 answers
497 views

For which series of finite simple groups is it algorithmically decidable whether they contain a homomorphic image of a given finitely presented group?

8 votes
2 answers
535 views

How hard is it to compute the diameter and the growth function of a finite permutation group of small degree?

8 votes
1 answer
454 views

Solvability of finite groups of order coprime to 15 -- proof without using CFSG?

8 votes
1 answer
338 views

Set of integers having finite intersection with the image of any polynomial of degree $\geq 2$

7 votes
1 answer
269 views

Catalogue of groups with short finite presentations

7 votes
2 answers
353 views

Smooth sums of coprime smooth integers

7 votes
1 answer
504 views

Is the mapping $f: \mathbb{R} \rightarrow [0,1], \ x \mapsto \sum_{n=1}^\infty \frac{\lfloor x^n \rfloor \mod 2}{2^n}$ surjective?

7 votes
0 answers
300 views

Does this class of groups contain finitely generated infinite periodic groups?

7 votes
0 answers
1k views

Example of a group with unsolvable word problem

6 votes
1 answer
368 views

Uniformity of the distribution of the prime numbers on the prime residue classes (mod $m$)

6 votes
0 answers
189 views

Finite simple groups of "smooth" order

5 votes
0 answers
143 views

Triples of integers a, b and c with a + b = c and specified prime divisors

5 votes
0 answers
134 views

The orders of which nonabelian finite simple groups can be written as products of other such orders?

5 votes
2 answers
155 views

Quotients of a 2-generated dense subgroup of a Cartesian product of infinitely many finite alternating groups

5 votes
0 answers
175 views

Can the integers in an easily computable sequence free of prime numbers always be factored easily?

5 votes
1 answer
274 views

When does there exist a convex polyhedron with given edge lengths?

5 votes
0 answers
236 views

Finite groups generated by 3 involutions interchanging disjoint residue classes of the integers

5 votes
1 answer
414 views

Nice diophantine equations with large smallest solutions

4 votes
0 answers
203 views

Monte Carlo variant of Hilbert's Tenth Problem