User YCor

72 votes

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In a topological space if there exists a loop that cannot be contracted to a point does there exist a simple loop that cannot be contracted also?

answered Aug 8, 2019 at 20:03

63 votes

How can a mathematician handle the pressure to discover something new?

answered Mar 11, 2018 at 18:44

50 votes

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Is there a smallest group containing all finite groups?

answered Oct 24, 2022 at 4:39

40 votes

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Are infinite groups in which most elements have order $\leq 2$ commutative?

answered Sep 18, 2018 at 7:33

37 votes

Bourbaki's definition of the number 1

answered Apr 15, 2020 at 13:45

37 votes

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divisors of $p^4+1$ of the form $kp+1$

answered Jun 7, 2015 at 11:23

36 votes

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Does GL_n(Z) have a noetherian group ring?

answered May 3, 2014 at 12:15

32 votes

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Does there exists a group structure on $\circ$ on $(\mathbb{R},\circ)$ such that $(\mathbb{R},\circ)$ is non-isomorphic to $(\mathbb{R},+)$?

answered Aug 25, 2018 at 14:27

31 votes

Is SO(4) a subgroup of SU(3)?

answered Nov 16, 2021 at 15:24

30 votes

Can one deduce the fundamental theorem of algebra from real calculus and linear algebra?

answered Mar 12, 2022 at 16:15

28 votes

Solvable groups that are linear over $\mathbb{C}$ but not over $\mathbb{Q}$?

answered Nov 16, 2023 at 6:40

28 votes

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Does $\mathbb{Q}$ embed into a finitely generated solvable group?

answered Jan 13, 2020 at 20:26

28 votes

Infinitely many finitely generated groups having the same Cayley graph

answered Mar 12, 2014 at 18:06

27 votes

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Is every finite group the outer automorphism group of a finite group?

answered Sep 25, 2020 at 11:50

26 votes

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Is $GL_n(\mathbb{Q}_p)=GL_n(\mathbb{Z}_p)GL_n(\mathbb{Q})$?

answered May 15, 2018 at 12:34

26 votes

Are all free groups linear, i.e., admit a faithful representation to GL(n,K) for some field K ?

answered Mar 19, 2013 at 16:07

26 votes

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The number of maximal subgroups up to isomorphism

answered May 12, 2016 at 16:23

25 votes

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Finitely generated group with $\aleph_0<X_G<2^{\aleph_0}$ normal subgroups?

answered Mar 18, 2014 at 17:54

25 votes

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Is there a differentiable map surjective from low to high dimension？

answered Oct 2, 2021 at 9:09

24 votes

Fundamental group of a Lie group

answered Mar 9, 2018 at 20:10

24 votes

Elementary proof that $\mathbb{R}^3 \setminus \{p_1,\dots,p_n\}$ is not homeomorphic to $\mathbb{R}^3$

answered Jan 6, 2021 at 18:06

24 votes

Uncountable counterexamples in algebra

answered May 9, 2021 at 20:09

23 votes

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Infinitely many finitely generated groups having the same Cayley graph

answered Mar 12, 2014 at 20:33

23 votes

A question about subsets of plane

answered Nov 24, 2016 at 9:03

23 votes

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Is there an eigenvalue of modulus larger than 1?

answered Feb 10, 2022 at 18:19

22 votes

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The number of polynomials on a finite group

answered Sep 2, 2022 at 12:20

21 votes

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Must the powers of some element always grow linearly with respect to a word metric?

answered Apr 12, 2015 at 19:54

21 votes

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Abelianization of general linear group of a polynomial ring

answered Apr 17, 2020 at 8:24

20 votes

Suggestions for special lectures at next ICM

answered Aug 6, 2020 at 18:11

20 votes

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Is there a non-free group $G$ whose subgroups are all freely decomposable?

answered Dec 15, 2020 at 22:08

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750 Answers

In a topological space if there exists a loop that cannot be contracted to a point does there exist a simple loop that cannot be contracted also?

How can a mathematician handle the pressure to discover something new?

Is there a smallest group containing all finite groups?

Are infinite groups in which most elements have order $\leq 2$ commutative?

Bourbaki's definition of the number 1

divisors of $p^4+1$ of the form $kp+1$

Does GL_n(Z) have a noetherian group ring?

Does there exists a group structure on $\circ$ on $(\mathbb{R},\circ)$ such that $(\mathbb{R},\circ)$ is non-isomorphic to $(\mathbb{R},+)$?

Is SO(4) a subgroup of SU(3)?

Can one deduce the fundamental theorem of algebra from real calculus and linear algebra?

Solvable groups that are linear over $\mathbb{C}$ but not over $\mathbb{Q}$?

Does $\mathbb{Q}$ embed into a finitely generated solvable group?

Infinitely many finitely generated groups having the same Cayley graph

Is every finite group the outer automorphism group of a finite group?

Is $GL_n(\mathbb{Q}_p)=GL_n(\mathbb{Z}_p)GL_n(\mathbb{Q})$?

Are all free groups linear, i.e., admit a faithful representation to GL(n,K) for some field K ?

The number of maximal subgroups up to isomorphism

Finitely generated group with $\aleph_0<X_G<2^{\aleph_0}$ normal subgroups?

Is there a differentiable map surjective from low to high dimension？

Fundamental group of a Lie group

Elementary proof that $\mathbb{R}^3 \setminus \{p_1,\dots,p_n\}$ is not homeomorphic to $\mathbb{R}^3$

Uncountable counterexamples in algebra

Infinitely many finitely generated groups having the same Cayley graph

A question about subsets of plane

Is there an eigenvalue of modulus larger than 1?

The number of polynomials on a finite group

Must the powers of some element always grow linearly with respect to a word metric?

Abelianization of general linear group of a polynomial ring

Suggestions for special lectures at next ICM

Is there a non-free group $G$ whose subgroups are all freely decomposable?