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yeshengkui
  • Member for 14 years, 4 months
  • Last seen more than 9 years ago
  • Oxford
27 votes
5 answers
3k views

Are there any nontrivial ring homomorphisms $M_{n+1}(R)\rightarrow M_n(R)$?

16 votes
3 answers
2k views

Is the group von Neumann algebra construction functorial?

14 votes
3 answers
3k views

The difference between $l^1(G)$ and the reduced group $C^*$ algebra $C_r^*(G)$

13 votes
3 answers
3k views

Zero divisor conjecture and idempotent conjecture

13 votes
2 answers
3k views

Is every homology theory given by a spectrum?

11 votes
1 answer
612 views

Is $SL(n,\mathbb{Z})$ a CAT(0) group?

8 votes
1 answer
718 views

Is this a characterization of Dedekind domain?

6 votes
1 answer
284 views

Projective modules over non-rational group rings

6 votes
1 answer
332 views

Integral group rings on which stably free modules are free

4 votes
4 answers
1k views

Are there some nontrivial group homomorphisms from $SL_n(\mathbb{Z})$ to $GL_{n-1}(\mathbb{Z})$ for $n\geq3$?

2 votes
1 answer
3k views

Does $S^2$ have a trivial normal bundle in any closed orientable manifold?

2 votes
1 answer
2k views

Is a normal subgroup of a finitely presented group finitely generated or normal finitely genrated?

1 vote
1 answer
412 views

Can an infinite conjugacy class in a group split into more than one conjugacy class in some subgroup of finite index?

1 vote
0 answers
98 views

PL or projective PL map on the links of a PL manifold

1 vote
1 answer
174 views

Does a dense submodule of a free module always contain a basis?

0 votes
1 answer
209 views

Non-trivial action of $SL_n(\mathbb{Z} )$ on a simplicial tree