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Hamiltonian systems, symplectic flows, classical integrable systems

31 votes
Accepted

How to see the Phase Space of a Physical System as the Cotangent Bundle

Let's start by answering the first question. Let $M$ be any manifold. Consider a physical system consisting of a point-particle moving on $M$. What are the configurations of this physical system? …
José Figueroa-O'Farrill's user avatar
27 votes
Accepted

The Jacobi Identity for the Poisson Bracket

The Jacobi identity for the Poisson bracket does indeed follow from the fact that $d\Omega =0$. I claim that (twice) the Jacobi identity for functions $f,g,h$ is precisely $$d\Omega(X_f,X_g,X_h) = 0. …
José Figueroa-O'Farrill's user avatar
17 votes
Accepted

Why can we define the moment map in this way (i.e. why is this form exact)?

Both answers are "No." There are well-known obstructions to the existence of an equivariant momentum mapping arising from the action by symplectomorphisms of a group $G$ on a symplectic manifold. Th …
José Figueroa-O'Farrill's user avatar
7 votes
Accepted

Question about the dimension of a Contact (Symplectic) manifold

And by popular request, here's my comment as an answer :) Your guess is correct. Contact structures are structures associated to a one-form $\alpha$ with maximal rank. There are two cases: for odd …
José Figueroa-O'Farrill's user avatar
6 votes
Accepted

Trivial canonical bundle of a Ricci-flat, simplyconnected Kähler manifold

The answer to the first question is that the Ricci tensor defines a (1,1) form (called the Ricci form) and this is the curvature of the connection on $K_M$ induced by the Levi-Civita connection on $T …
José Figueroa-O'Farrill's user avatar
5 votes

Reference for Almost-Kahler geometry

The paper that started this all is the one by Gray and Hervella where they classified the different types of almost Hermitian structures. It's a classic and still very much well worth reading: The s …
José Figueroa-O'Farrill's user avatar
4 votes
Accepted

coisotropic submanifolds

Locally, any codimension-$k$ submanifold can be described as the zero locus of $k$ smooth functions $f_1,\dots,f_k$. (This is true globally if and only if the submanifold has trivial normal bundle.) …
José Figueroa-O'Farrill's user avatar
3 votes

Is the 'massive' Calogero-Moser system still integrable?

Just to add to Gjergji Zaimi's answer, Harry Braden has sent me the expressions for the conserved charges responsible for the integrability of the $N=3$ model: The total momentum $P = p_1 + p_2 + p_ …
José Figueroa-O'Farrill's user avatar
2 votes
Accepted

coisotropic submanifolds on poisson manifolds

The answer is 'Yes', at least with some additional transversality conditions. Corollary (1.2.6) in Weinstein's Coisotropic calculus and Poisson groupoids states that Let $M$ be a submanifold of t …
José Figueroa-O'Farrill's user avatar
1 vote

Question about the definition of hamiltonian group action.

Your belief is only partially correct. The existence of a momentum map requires two conditions: First, as you point out, if $X^*$ is the fundamental vector field corresponding to $X \in \mathfrak{g …
José Figueroa-O'Farrill's user avatar