6,858 reputation
12443
bio website www-fourier.ujf-grenoble.fr/…
location Grenoble, France
age 34
visits member for 4 years, 5 months
seen Aug 8 at 20:04
I am a teacher and researcher at Université Joseph Fourier.

Aug
8
answered Top specialized journals
Aug
8
comment Top specialized journals
I think that the recent Journal of modern dynamics actually is on par with ETDS, don't you think?
Aug
7
comment Can anything be said of the correlation of X and Y / X?
This question does not belong here and I voted to close, but I think it does not hurt to give you an idea of what might happen: you have to recall that correlation only measures the affine dependency between variables, not other kind of dependency. Imagine for example that $Y=X^2$: then $Y$ is entirely determined by the value of $X$, but their correlation can be very weak (it is zero when $X$ has a law symmetric with respect to the origin). On the other hand, $X$ and $Y/X$ are the same variable.
Aug
3
comment Dimension Leaps
@RyanBudney: There is a convincing brief explanation, or rather hint of this phenomenons on the fourth cover page of Scorpan's book on 4-dimensional manifolds: dimension 4 is large enough to allow strange things to happen, but too small to enable one to undo them. In particular, the fact that many problems have been understood in dimension 5 and greater seems to be due to the fact that strange things can happen in principle, but that they are in fact not strange (i.e. they can be shown to be equivalent to non-strange things by using the room given by the high dimension).
Aug
2
reviewed Reject suggested edit on nontrivial theorems with trivial proofs
Aug
2
reviewed Approve suggested edit on (reference request) Chaitin's constant is incompressible
Aug
1
reviewed Approve suggested edit on Cohomology of Lie groups and Lie algebras
Jul
28
comment First return time in an interval for N particles rotating on the circle at constant random speeds
You are simply looking at a translation flow on the $N$-torus, so volume consideration will give you an easy (uniform) upper bound. I guess that other properties, dependent on the chosen measure, should be reachable with this point of view.
Jul
25
comment If there is a dense geodesic, are almost all geodesics equidistributed? Dense?
@VesselinDimitrov: no, the submanifold is the Riemannian product of an embedded strictly convex circle in the sphere, by a straight line, so it is strictly mean convex. So the latest version of question 2 is still false.
Jul
23
comment Proof synopsis collection
@Michael: I partly agree, and changed a bit my answer to credit Hamilton. I would not say that the last sentence could, as it is, be credited to him though: he only got this under the strong hypothesis that the initial metric is positively Ricci curved.
Jul
23
revised Proof synopsis collection
Added some (deserved) credit to Hamilton
Jul
23
comment Computations with the distance function on a Riemannian manifold
You will find definition of the monotone rearrangement in many books on optimal transportation (e.g. one of Villani's books). In words, it is the measure on $[0,+\infty)^2$ that has marginals $\mu$ and $\mu^*$, and which ``maps'' the leftmost part of the mass of $\mu$ to the leftmost part of the mass of $\mu^*$.
Jul
21
comment Generic path in the space of vector fields on the orientable surface
@MaximPrasolov: your last comments answers mine perfectly. Considering the previous one, it rings a bell; did you try to apply the methods of Emmanuel Giroux? I guess you know about them, but just in case I think that the most relevant paper is "Structures de contact en dimension trois et bifurcations des feuilletages de surfaces." [Contact structures in dimension three and bifurcations of surface foliations] Invent. Math. 141 (2000), no. 3, 615–689. It is in French but there should be some accounts of these works in english, at least I know who to ask.
Jul
21
answered If there is a dense geodesic, are almost all geodesics equidistributed? Dense?
Jul
20
comment Generic path in the space of vector fields on the orientable surface
A one-parameter family of vector field is an horizontal vector field on the product $\Sigma\times I$ where $\Sigma$ is the surface $I$ is an interval, and ``horizontal'' means tangent to the slices $\Sigma\times\{t\}$. Now, did you try to apply classical genericity results on this horizontal vector field (and then projects the obtained vector field to an horizontal one)?
Jul
16
reviewed Approve suggested edit on Breaking efficiently a binary sequence into given strings
Jul
2
awarded  Curious
Jul
2
awarded  Electorate
Jun
30
awarded  Revival
Jun
30
answered Computations with the distance function on a Riemannian manifold