331

Answers

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55

Why is BG infinite dimensional for G finite ?

29

Parallelizability of the Milnor’s exotic spheres in dimension 7

27

Can we ascertain that there exist an epimorphism $G\rightarrow H?$

26

Proofs without words

26

Level sets of Morse functions

24

Is it possible to capture a sphere in a knot?

22

What do Weierstrass points look like?

21

isotopy inverse embeddings vs. diffeomorphisms

20

Not especially famous, long-open problems which anyone can understand

20

What are some interesting corollaries of the classification of finite simple groups?

19

Does this approach for the Poincare conjecture work?

17

What makes four dimensions special?

17

Elevator pitch for the Virtual Fibering Theorem

16

Are there any non-planar graphs containing only K(3,3) as a subgraph that are not 4-colourable?

16

Consequences of the Langlands program

16

How people think about ending lamination?

16

conformally flat manifold with positive scalar curvature

16

Complete knot invariant?

16

Does every finitely presentable group have a presentation that simultaneously minimizes the number of generators and number of relators?

15

Distinguishing congruence subgroups of the modular group

15

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

15

Does Ricci flow with surgery come from sections of a smooth Riemannian manifold?

14

Compactification theorem for differentiable manifolds ?

14

Diffeomorphism of 3-manifolds

14

Largest hyperbolic disk embeddable in Euclidean 3-space?

14

Metric spheres in CAT(0) manifolds

14

What finitely presented groups embed into GL_2?

13

Beautiful descriptions of exceptional groups

13

Independent evidence for the classification of topological 4-manifolds?

13

Why should I care about Heegaard-Floer theory?