6,772 reputation
1937
bio website www2.unine.ch/alain.valette
location Neuchâtel, Switzerland
age 55
visits member for 3 years, 5 months
seen 8 hours ago

Sep
7
comment Kadison-Singer problem
If you read french, please consider having a look at: bourbaki.ens.fr/TEXTES/1088.pdf
Aug
20
awarded  Nice Answer
Jul
2
awarded  Curious
May
29
comment quantum states and observables for the non-commutative torus
$A_\theta$ can be obtained as the $C^*$-algebra generated by two unitaries on $\ell^2(\mathbb{Z}^2)$ associated with the formulation of the problem of the Bloch electron (describe the motion of a free electron on the square lattice submitted to a uniform magnetic field orthogonal to the lattice). See a famous paper by D. Hofstadter: zimp.zju.edu.cn/~xinwan/qm2/note/…
Apr
28
revised Spectral gap of unitary representation
Precision added
Apr
28
answered Spectral gap of unitary representation
Apr
18
awarded  Yearling
Feb
20
awarded  Enlightened
Feb
20
awarded  Nice Answer
Jan
25
answered Learning about Lie groups
Jan
23
comment Why aren't fields called “bodies” instead?
A remark on local versions of french: the Belgians use "champ" (= field) for "corps commutatif", while the Swiss say as the French...
Jan
19
comment A question on lie groups( Lie algebras)
Take Sasha's example, and embed it into the simple Lie group $SU(3)$ (where $\mathbb{T}^2$ embeds as a maximal torus).
Jan
12
answered Modern Mathematical Achievements Accessible to Undergraduates
Jan
8
comment Reflexive (hyperbolic) graphs
I see. Thanks for clarifying.
Jan
8
comment Reflexive (hyperbolic) graphs
Why are you using "hyperbolic" in the title? (for me, hyperbolic graphs are graphs which are hyperbolic when viewed as metric spaces, which seems irrelevant to your question...)
Jan
8
comment Which groups are the unitary group of a $C^*$-algebra
You might also take the reduced C*-algebra. But in my view it says nothing about the OP (with due respect).
Jan
6
comment Why we need to study representations of matrix groups?
@Andy: I agree that the question produced some good answers. On the other hand, this basic question should be answered in any introductory book in representation theory (even if it is not always so, unfortunately...)
Jan
6
comment Le Gall's equivariant KK-theory and twisted equivariant KK-theory
If you succeed in getting a copy of Le Gall's thesis (probably available from Le Gall), I sort of remember that it is more detailed than the paper...
Jan
6
comment Le Gall's equivariant KK-theory and twisted equivariant KK-theory
Have you tried this? portico.org/Portico/browse/access/…
Jan
6
comment Why we need to study representations of matrix groups?
This would be a good question for MathStackExchange.