There can be no real individual freedom in the presence of economic insecurity.
by Chester Bowles (1901 - 1986)



A catholic cemetery with tombs of some of my ancestors:


Continue reading Ancestors

Stock Market in Hanoi

Hundreds of people gluing their eyes to a price screen in a brokerage house in Hanoi, 04/Apr/2007

A day in Saigon


Breakfast in this small busy street (Kim Ngân, Tin Dô & my family)

Another street in the center of Saigon (Nguyen Du str. ?)

Lunch at “Bach Duong” restaurant, with Hong Phuong:

Reunification Palace:

Seafood dinner, with Mai’s friends:

. . . → Read More: A day in Saigon

Normal forms of Hamiltonian vector fields on e*(3) ?

e(3) = so(3) x R^3 (semidirect product)

We have shown with Ph. Monnier a normal form a la Birkhoff for Hamiltonian vector fields on the dual of a semisimple Lie algebra.  But what about the case of e(3) and other non-semisimple Lie algebras ?

e(3) is an important particular case because it appears in . . . → Read More: Normal forms of Hamiltonian vector fields on e*(3) ?

my sister and I

long long time ago

Cushman conference 26/March/2007

me trying to explain normal forms of vector fields on Poisson manifolds

Conference in honour of Richard Cushman, “Dynamics and Hamiltonian Systems”, Utrecht 2630/March/2007

Unfortunately I’ll have to go back to Toulouse on 28/March and miss a large part of the conference.

Dinner on 23 March 2007

Dinner with Rui Fernandes, Boris Kruglikov, Eva Miranda and Philippe Monnier (on the occasion of the visits of Boris and Rui in Toulouse)

Another photo, taken by Boris:

non-integrability of hamiltonian systems on g*

I’m currently struggling with the following problem:

Given a generic quadratic function Q on g* (where g is a simple Lie algebra) which Poisson-commute with a Cartan subalgebra t of g, show that the Hamiltonian system of Q does not admit any other first integral exept the obvious ones (the ones which can be . . . → Read More: non-integrability of hamiltonian systems on g*


Je viens d’apprendre qu’il y a 2 douches dans le batiment 1R3 de notre Institut. Donc on peut faire du jogging, du tennis, etc. et prendre une douche après, à l’Institut.

my first bike ?

at home, Hanoi, circa 1981

with Philippe Monnier

Lisbon 2003

On top of Titov

Titov island, Halong Bay, 06/2006

Non-Hamiltonian version of Morales-Ramis theorem

A student of mine, Michael Ayoul, is currently writing up the non-Hamiltonian version of Morales-Ramis(-Simo) theorem, which says that the differential Galois group of the variational equation (of any order) of a meromorphic integrable  system along a solution must be Abelian.

He will then try to apply this result to various non-Hamiltonian (non-holonomous) systems . . . → Read More: Non-Hamiltonian version of Morales-Ramis theorem