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Mikko Korhonen's user avatar
Mikko Korhonen's user avatar
Mikko Korhonen's user avatar
Mikko Korhonen
  • Member for 12 years, 7 months
  • Last seen this week
88 votes
3 answers
12k views

Does every Abelian group admit a ring structure?

30 votes
3 answers
5k views

When does every group with order divisible by $n$ have a subgroup of order $n$?

27 votes
6 answers
2k views

Upper bounds on the size of $\operatorname{Aut}(G)$

25 votes
2 answers
1k views

Lower bounds on the number of elements in Sylow subgroups

19 votes
4 answers
2k views

If $(|G|, |H|) > 1$, does it follow that $\operatorname{Aut}(G \times H) \neq \operatorname{Aut}(G) \times \operatorname{Aut}(H)$?

17 votes
2 answers
499 views

Why does calculating matrix inverses, roots, etc. using the spectrum of a matrix work?

15 votes
2 answers
1k views

If $p$ is an odd prime, does every Sylow $p$-subgroup contain an element not in any other Sylow $p$-subgroup?

13 votes
1 answer
695 views

Which families of groups have interesting formulas for the number of elements of given order?

12 votes
2 answers
1k views

If $H$ and $G/H$ are compact, then $G$ is compact.

12 votes
1 answer
349 views

What is the smallest $n$ for which the usual "counting sizes of conjugacy classes" proof of simplicity fails for $A_n$?

11 votes
1 answer
978 views

Finding an outer automorphism of $S_6$

11 votes
2 answers
2k views

Linear independence of $n$th roots over $\mathbb{Q}$

10 votes
2 answers
3k views

If derivative of a function is the zero function in $\mathbb R^n$, then the function is constant when the domain is path-connected

8 votes
1 answer
199 views

In a group, does $[G:H] \leq |N|$ always imply $[G:N] \leq|H|$?

7 votes
3 answers
944 views

Where can I find the original papers by Frobenius concerning solutions to $x^n = 1$ in a finite group?

6 votes
3 answers
1k views

Proving a commutator identity for groups

6 votes
1 answer
407 views

Existence of a basic sequence with basis constant $1$ in a Banach space

4 votes
2 answers
245 views

Coincidences with orders of simple groups

4 votes
2 answers
494 views

Noncommutative rings, finding $a$ and $b$ such that every term in the sum $(a+b)^n = a^n + a^{n-1}b + \ldots$ is distinct

3 votes
1 answer
1k views

Equal quotient groups

1 vote
0 answers
129 views

Isomorphic subgroups and normality [duplicate]