User Allen Hatcher

11 votes

Accepted

Homotopy versus path-homotopy on punctured surface

answered Dec 14, 2013 at 16:32

11 votes

Accepted

Simplicial complexes vs. geometric realization of abstract simplicial complexes

answered May 7, 2010 at 1:46

11 votes

Accepted

Convergence of spectral sequences of cohomological type

answered Mar 18, 2010 at 13:44

10 votes

Computing the structure of the group completion of an abelian monoid, how hard can it be?

answered Feb 4, 2010 at 13:44

10 votes

One question on cup product and torsion elements

answered Jun 6, 2013 at 9:12

10 votes

Accepted

A query about Hatcher flow on arc complex

answered Aug 18, 2014 at 14:17

10 votes

Group cohomology of Q/Z

answered Jul 18, 2020 at 17:38

10 votes

Accepted

Generalized Schoenflies - formalizing step in proof?

answered Oct 24, 2020 at 0:41

10 votes

Accepted

Handle decompositions using only 1-handles

answered Aug 25, 2017 at 17:26

9 votes

Accepted

Homology of simplicial complex versus homology of simplicial _set_

answered Dec 9, 2017 at 4:09

9 votes

Non-zero homotopy/homology in diffeomorphism groups

answered Feb 13, 2018 at 19:10

9 votes

Accepted

Self-indexing Morse functions on non-compact manifolds

answered Apr 23, 2013 at 5:21

8 votes

Accepted

Embedding $S_3$ into $Aut(F_2)$

answered May 17, 2011 at 2:11

8 votes

If you break a stick at two points chosen uniformly, the probability the three resulting sticks form a triangle is 1/4. Is there a nice proof of this?

answered Jun 4, 2011 at 14:26

8 votes

Reducible 3d torus bundles

answered Dec 13, 2009 at 1:29

8 votes

distance formula in Farey graph?

answered Jul 23, 2010 at 17:56

8 votes

Accepted

Representation of two related integers by the same binary quadratic form

answered Jun 18, 2019 at 20:30

8 votes

Accepted

Cup product of cohomology in a Serre spectral sequence

answered Sep 25, 2015 at 13:58

8 votes

Accepted

Existence of an isotopy in Riemannian manifold

answered Mar 31, 2019 at 14:52

8 votes

Cohomology version of Moore space

answered Nov 25 at 16:47

7 votes

What are the possible automorphism groups of Riemann surfaces of low genus?

answered Sep 21, 2015 at 1:10

7 votes

Lens spaces and generalized Petersen graphs

answered Dec 9, 2014 at 17:11

7 votes

Accepted

positions of regular cubes in Euclidean space with all its vertices without distinction

answered Nov 1, 2015 at 12:08

7 votes

Equivalence relations of topological spaces not comparable with homotopy

answered Nov 5, 2015 at 21:33

7 votes

Loopspace of an Eilenberg Maclane space K(G,n)

answered Sep 30, 2010 at 12:40

7 votes

When are the homology and cohomology Hopf algebras of topological groups equal?

answered Jun 17, 2010 at 14:16

7 votes

Spheres over rational numbers and other fields

answered Feb 17, 2010 at 0:23

7 votes

Commutator subgroup of $\Gamma(2).$

answered Jan 11, 2011 at 17:29

7 votes

Accepted

Moore decomposition, dual to Postnikov tower

answered Jan 20, 2014 at 19:51

7 votes

In a fibration, can a deformation retraction of the base be lifted to the total space?

answered Aug 21, 2014 at 1:52

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114 Answers

Homotopy versus path-homotopy on punctured surface

Simplicial complexes vs. geometric realization of abstract simplicial complexes

Convergence of spectral sequences of cohomological type

Computing the structure of the group completion of an abelian monoid, how hard can it be?

One question on cup product and torsion elements

A query about Hatcher flow on arc complex

Group cohomology of Q/Z

Generalized Schoenflies - formalizing step in proof?

Handle decompositions using only 1-handles

Homology of simplicial complex versus homology of simplicial _set_

Non-zero homotopy/homology in diffeomorphism groups

Self-indexing Morse functions on non-compact manifolds

Embedding $S_3$ into $Aut(F_2)$

If you break a stick at two points chosen uniformly, the probability the three resulting sticks form a triangle is 1/4. Is there a nice proof of this?

Reducible 3d torus bundles

distance formula in Farey graph?

Representation of two related integers by the same binary quadratic form

Cup product of cohomology in a Serre spectral sequence

Existence of an isotopy in Riemannian manifold

Cohomology version of Moore space

What are the possible automorphism groups of Riemann surfaces of low genus?

Lens spaces and generalized Petersen graphs

positions of regular cubes in Euclidean space with all its vertices without distinction

Equivalence relations of topological spaces not comparable with homotopy

Loopspace of an Eilenberg Maclane space K(G,n)

When are the homology and cohomology Hopf algebras of topological groups equal?

Spheres over rational numbers and other fields

Commutator subgroup of $\Gamma(2).$

Moore decomposition, dual to Postnikov tower

In a fibration, can a deformation retraction of the base be lifted to the total space?