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Hamiltonian systems, symplectic flows, classical integrable systems

19 votes
2 answers
1k views

The symplectic geometry of cold coconuts

Consider the open set $M \subset \mathbb{C}^{2}$ given by the union of the unit ball $|z_1|^2 + |z_{2}|^2 < 1$ (the coconut) and the cylinder $|z_1| < \epsilon$, $0 < \epsilon < \! \!< 1$, (the straw …
alvarezpaiva's user avatar
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11 votes
0 answers
550 views

Poincaré recurrence and symplectic packings

Question. Is there any example of a path connected symplectic manifold $(M,\omega)$ that has infinite volume, but which cannot be packed by an infinite number of symplectic balls of a fixed radius $r$ …
alvarezpaiva's user avatar
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8 votes
1 answer
402 views

From convex geometry to contact topology

Here is a problem in contact topology that was suggested by Petya's answer to this mathoverflow question of mine. Let $S^* \mathbb{R}^n$ be the space of cooriented contact elements of $\mathbb{R}^n$. …
alvarezpaiva's user avatar
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8 votes
1 answer
871 views

Formula for the Haar measure in the linear symplectic group

What is (or where can I find) an explicit formula for the Haar measure of the group of linear symplectic transformations of $\mathbb{R}^{2n}$? Added 13/05/2014. Some clarifying remarks: (1) by symp …
alvarezpaiva's user avatar
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7 votes
2 answers
262 views

Oriented double normals

Given an embedded two-torus in three-dimensional Euclidean space, paint the inside of the torus red and the outside blue. Show that there is an oriented line in ${\mathbb R}^3$ that cuts the torus per …
alvarezpaiva's user avatar
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6 votes
1 answer
847 views

Shortest geodesic loop vs. shortest periodic geodesic

Are there simple conditions on a Riemannian metric on the two-sphere that imply that a geodesic loop of minimal length is actually a periodic geodesic? For example, is this true for small perturbatio …
alvarezpaiva's user avatar
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6 votes
1 answer
404 views

Non-Reeb vector fields on the three-sphere

Let $X$ be the Hopf vector field on the three-sphere. Is there a smooth nowhere zero function $f$ so that the modified vector field $fX$ is not the Reeb vector field of any contact form on the three-s …
alvarezpaiva's user avatar
  • 13.5k
6 votes
1 answer
374 views

Symplectic Koopmanism

Let $(M, \omega)$ be a $2n$-dimensional symplectic manifold and let $L_2(M,|\omega^n|)$ be the Hilbert space of complex-valued functions on $M$ that are square integrable with respect to the Liouville …
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2 votes
0 answers
144 views

Flow on invariant Lagrangian tori

The most concrete version of the question is : A (necessarily) invariant Lagrangian torus $L$ on the unit cotangent of a Riemannian metric on the two-torus carries a periodic orbit with period $T$. I …
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