HJRW's user avatar
HJRW's user avatar
HJRW's user avatar
HJRW
  • Member for 14 years, 4 months
  • Last seen this week
47 votes

Most interesting mathematics mistake?

43 votes

What are some of the big open problems in 3-manifold theory?

39 votes

finite generated group realized as fundamental group of manifolds

36 votes

What are your favorite instructional counterexamples?

29 votes

Can a group be a universal Turing machine?

27 votes
Accepted

Mapping from a finite index subgroup onto the whole group

27 votes
Accepted

Does injectivity of $\pi_1(\partial U) \to \pi_1(M)$ imply injectivity of $\pi_1(U) \to \pi_1(M)$?

25 votes
Accepted

Primes occurring as orders of elements of a finitely presented group

25 votes
Accepted

Fundamental group of 3-manifold with boundary

23 votes
Accepted

Modern references on hyperbolic groups

21 votes
Accepted

Does the injection $\text{Aut}(F_n) \hookrightarrow \text{Aut}(F_{n+1})$ split?

21 votes

When is a extension of $\mathbb{Z}$ by a free group a CAT(0) group?

21 votes

Fundamental groups of closed hyperbolic 3-manifolds are freely indecomposable

20 votes

〈x,y : x^p = y^p = (xy)^p = 1〉

19 votes
Accepted

What are the implications of the simple loop conjecture?

19 votes
Accepted

A result of Schützenberger on commutators and powers in free groups

19 votes

Residual finiteness: why do we care?

19 votes

Acyclic group and finite CW-complex

18 votes

Examples of locally hyperbolic groups

18 votes
Accepted

Is there a finitely presented group with infinite homology over $\mathbb{Q}$?

17 votes
Accepted

Is the diagonal of finitely presented groups computable?

17 votes

How helpful is non-standard analysis?

17 votes

When is a finitely generated group finitely presented?

17 votes

A single paper everyone should read?

17 votes

Applications of the notion of of Gromov-Hausdorff distance

16 votes
Accepted

Conjugacy classes of the mapping class group

15 votes
Accepted

Number of subgroups of a given index of a free group

15 votes

Understanding groups that are not linear

15 votes
Accepted

Judging whether a finitely presented group is a 3-manifold group?

15 votes
Accepted

Finitely generated subgroups with infinite cyclic quotient

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