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Top Questions
32 votes

Second Betti number of lattices in $\mathrm{SL}_3(\mathbf{R})$

at.algebraic-topology gr.group-theory gt.geometric-topology lie-groups group-cohomology asked Oct 27, 2018 at 12:19
mathoverflow.net

27 votes

Group with finite outer automorphism group and large center

gr.group-theory kt.k-theory-and-homology geometric-group-theory algebraic-k-theory asked May 14, 2015 at 15:30
mathoverflow.net

27 votes

Sustainability of ZBmath unrestricted access

soft-question journals zbmath asked Sep 24, 2020 at 10:52
mathoverflow.net

19 votes

Is Thompson's group definably orderable?

gr.group-theory model-theory ordered-groups asked Mar 12, 2020 at 10:33
mathoverflow.net

17 votes

Finitely generated groups with Hölder-exotic space of ends?

gr.group-theory gt.geometric-topology mg.metric-geometry geometric-group-theory asked Mar 20, 2018 at 14:17
mathoverflow.net

13 votes

Linear occurrences of finite simple groups

gr.group-theory finite-groups asked Sep 8, 2015 at 12:28
mathoverflow.net

13 votes

Variety of nilpotent Lie algebras or $p$-groups

gr.group-theory lie-algebras finite-groups p-groups nilpotent-groups asked Sep 21, 2014 at 18:09
mathoverflow.net

12 votes

Near permutation $n\mapsto n+1$ not conjugate to its inverse on the Stone-Čech remainder?

gr.group-theory set-theory gn.general-topology boolean-algebras stone-cech-compactification asked Feb 18, 2020 at 15:42
mathoverflow.net

10 votes

Generalized cancelation properties ensuring a monoid embeds into a group

gr.group-theory semigroups-and-monoids universal-algebra asked Dec 7, 2020 at 14:50
mathoverflow.net

10 votes

Quotients by algebraic group actions at the level of the Grothendieck ring

ag.algebraic-geometry algebraic-groups invariant-theory grothendieck-rings asked Dec 1, 2020 at 10:21
mathoverflow.net

1 2 3

Top Answers
65
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?
mathoverflow.net

58
How can a mathematician handle the pressure to discover something new?
mathoverflow.net

39
Are infinite groups in which most elements have order $\leq 2$ commutative?
mathoverflow.net

37
divisors of $p^4+1$ of the form $kp+1$
mathoverflow.net

37
Under what conditions is the exponential map on a Lie algebra injective?
math.stackexchange.com

37
Bourbaki's definition of the number 1
mathoverflow.net

36
Does GL_n(Z) have a noetherian group ring?
mathoverflow.net

32
Does there exists a group structure on $\circ$ on $(\mathbb{R},\circ)$ such that $(\mathbb{R},\circ)$ is non-isomorphic to $(\mathbb{R},+)$?
mathoverflow.net

30
Can one deduce the fundamental theorem of algebra from real calculus and linear algebra?
mathoverflow.net

30
Is SO(4) a subgroup of SU(3)?
mathoverflow.net

28
Does $\mathbb{Q}$ embed into a finitely generated solvable group?
mathoverflow.net

27
Are all free groups linear, i.e., admit a faithful representation to GL(n,K) for some field K ?
mathoverflow.net

27
Infinitely many finitely generated groups having the same Cayley graph
mathoverflow.net

26
The number of maximal subgroups up to isomorphism
mathoverflow.net

26
Is $GL_n(\mathbb{Q}_p)=GL_n(\mathbb{Z}_p)GL_n(\mathbb{Q})$?
mathoverflow.net

25
Is there a differentiable map surjective from low to high dimension？
mathoverflow.net

25
Finitely generated group with $\aleph_0<X_G<2^{\aleph_0}$ normal subgroups?
mathoverflow.net

24
Elementary proof that $\mathbb{R}^3 \setminus \{p_1,\dots,p_n\}$ is not homeomorphic to $\mathbb{R}^3$
mathoverflow.net

24
Is every finite group the outer automorphism group of a finite group?
mathoverflow.net

23
A question about subsets of plane
mathoverflow.net

23
Fundamental group of a Lie group
mathoverflow.net

23
Uncountable counterexamples in algebra
mathoverflow.net

22
Is there an eigenvalue of modulus larger than 1?
mathoverflow.net

22
Infinitely many finitely generated groups having the same Cayley graph
mathoverflow.net

21
Abelianization of general linear group of a polynomial ring
mathoverflow.net

21
Must the powers of some element always grow linearly with respect to a word metric?
mathoverflow.net

20
Topological semi-direct products of groups
mathoverflow.net

20
Finitely generated matrix groups whose eigenvalues are all algebraic
mathoverflow.net

19
Is there a non-free group $G$ whose subgroups are all freely decomposable?
mathoverflow.net

19
Suggestions for special lectures at next ICM
mathoverflow.net

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