Jens Reinhold's user avatar
Jens Reinhold's user avatar
Jens Reinhold's user avatar
Jens Reinhold
  • Member for 11 years, 11 months
  • Last seen more than a week ago
82 votes
23 answers
10k views

Solving algebraic problems with topology

34 votes
5 answers
3k views

The origin(s) of the word "elliptic"

23 votes
1 answer
849 views

Groups whose finite index subgroups of fixed index are isomorphic

23 votes
3 answers
2k views

Generalization of Borsuk-Ulam

23 votes
1 answer
1k views

Is every degree 1 self-map a homotopy equivalence?

19 votes
3 answers
1k views

Failure of Mostow rigidity in dimension 2

19 votes
1 answer
741 views

Which cohomology classes are detected by tori?

19 votes
1 answer
504 views

Can every manifold be dominated by a parallelizable one?

18 votes
1 answer
1k views

Is every sequence that looks like an AP really an AP?

18 votes
1 answer
813 views

Oriented cobordism classes represented by rational homology spheres

18 votes
1 answer
610 views

On the definition of A-theory

18 votes
1 answer
1k views

Simply connected finite CW-complex with only finitely many nontrivial homotopy and homology groups

17 votes
0 answers
552 views

Bernoulli & Betti numbers (of manifolds) and the prime 34511

16 votes
0 answers
260 views

Fibrations whose total spaces are more highly connected than their fibers

16 votes
3 answers
3k views

Homology equivalence and isomorphism on $\pi_1$ not enough for homotopy equivalence?

16 votes
1 answer
1k views

Evaluating a remarkable term for primes p = 5 (mod. 8)

16 votes
1 answer
471 views

How many cells needed to build the classifying space $BG$?

14 votes
1 answer
437 views

Non-phantom maps from $\mathbb CP^{\infty}$ to a finite complex

14 votes
1 answer
338 views

Vector bundles with exactly one nonzero SW-class

14 votes
1 answer
317 views

On the homological dimension of a Borel construction

13 votes
1 answer
549 views

Realizing symmetric groups by diffeomorphisms

13 votes
1 answer
816 views

When is $X \rightarrow \text{Spec}(C(X))$ a homeomorphism?

12 votes
2 answers
601 views

Cohomological obstructions to lift $\pi_0$ of a topological group

12 votes
4 answers
520 views

Is $\mathrm{Diff}_0(S_g)$ torsion-free?

12 votes
0 answers
369 views

Two ways a manifold can have little symmetry

12 votes
2 answers
849 views

Stable homotopy groups of $RP^{\infty}$

12 votes
0 answers
197 views

Examples of manifolds with first nontrivial SW-class in degree 16 or bigger

11 votes
2 answers
585 views

Constraints on the homology of amenable groups

11 votes
3 answers
870 views

Fixed point set of smooth circle action

11 votes
0 answers
157 views

Characterization of certain 4-dimensional lattices