Ralph's user avatar
Ralph's user avatar
Ralph's user avatar
Ralph
  • Member for 13 years, 5 months
  • Last seen more than 9 years ago
26 votes

Is strong approximation difficult?

26 votes
Accepted

Non-split extension of the rationals by the integers

20 votes
Accepted

When is an acylic chain complex contractible

17 votes

Is a domain all of whose localizations are noetherian itself noetherian ?

16 votes
Accepted

Does the knowledge of $Z(G)$ and $G/Z(G)$ give the full group?

15 votes
Accepted

Is a bialgebra with all group-like elements invertible a Hopf algebra?

14 votes

Subgroups of GL(2,q)

14 votes

When does a homomorphism factor through a free group?

14 votes

Which topological spaces are (topological) groups?

13 votes

p-group with large center

13 votes
Accepted

Can Ext over a group ring always be expressed as group cohomology ?

13 votes
Accepted

non-commutative finite rings

13 votes
Accepted

Orthogonality in non-inner product spaces

12 votes

functions satisfying "one-one iff onto"

12 votes
Accepted

A map inducing isomorphisms on homology but not on homotopy

12 votes
Accepted

Where else do the (topology) separation axioms turn up?

12 votes
Accepted

How to Compute Transgressions in a Serre Spectral Sequence?

12 votes
Accepted

Projective objects in the category of chain complexes

12 votes
Accepted

Homomorphisms from powers of Z to Z

11 votes

Projective objects in the category of chain complexes

11 votes
Accepted

Jacobson's theorem and further

11 votes

Blackbox Theorems

11 votes

The coproduct on the cohomology of a Hopf algebra

11 votes

Non-vanishing of group cohomology in sufficiently high degree

11 votes

Invariants and base change

10 votes

On two spectral sequences for the cohomology of a double complex

10 votes

Annihilators in Matrix Rings

10 votes
Accepted

About Tate's computation of $K_2^{\rm M}(\mathbb Q)$

10 votes
Accepted

rationalized K-Theory of the group ring of finite cyclic groups

10 votes

Cohomology ring of BG

1
2 3 4 5 6