6,802 reputation
1938
bio website www2.unine.ch/alain.valette
location Neuchâtel, Switzerland
age 55
visits member for 3 years, 6 months
seen 8 hours ago

Oct
11
revised Milnor-Wolf result on growth of solvable groups
Corrected 2 typos
Sep
30
awarded  Explainer
Sep
26
comment Morita Equivalence of Full Corners in $C^*$-algebras
The answer to (2) is yes, as $X=pA$ is an imprimitivity bimodule between $B$ and $A$. So if $E$ is a (left) projective finite type module over $A$, then $X\otimes_A E$ is projective finite type over $B$.
Sep
26
comment Basics on lattice in classical groups
The determinant maps $GL_n(\mathbb{Z})$ to $\{\pm 1\}$, so it is not a lattice in $GL_n(\mathbb{R})$. About references: as a beginner you may enjoy the book by Dave Witte-Morris: people.uleth.ca/%7Edave.morris/books/IntroArithGroups.html
Sep
20
comment Separability of the C*-algebra in the definition of K-homology
I completely agree with Paul. One difficulty of working with dual algebras is illustrated by my old paper: projecteuclid.org/download/pdf_1/euclid.pjm/1102720214 in which I tried to get a new proof of the Pimsner-Voiculescu 6-terms exact sequence... but I could only get a 5-terms sequence!
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...)