Symplectic geometry is a branch of differential geometry and differential topology which studies symplectic manifolds; that is, differentiable manifolds equipped with a closed, nondegenerate 2-form.

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Easy classical physics made mathematically rigorous!

Consider the following: We are given a symplectic manifold $M$. Now, we define a Hamilton function $H : M \rightarrow \mathbb{R}.$ Additionally, we want that $H^{-1}(x)=:M_x$ is a submanifold. We can ...
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Gaussian unitary dilation of Gaussian channels

I am starting with a few definitions. All these are standard and can be accessed from some quantum information or quantum physics books, for instance the books by Holevo or Parthasarathy. The question ...
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Why is Chirikov Map is a Twist Map?

Chirikov Map, also know as Standard Map, is define by $$ X(x,y)= x + y - \frac{k}{2\pi}\sin{2\pi x} \\ Y(x,y)=y - \frac{k}{2\pi}\sin{2\pi x}$$ the definition 4.1 given by Christophe Golé, in the book ...
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Symplectic manifold

Let ($M$, $\omega$) be a symplectic manifold of dimension $2n$. Then $\omega$ is non-degenerate $2-form$ by definition. Now, my question is if we can conclude that $\omega \wedge ...\wedge \omega$ ...
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24 views

Hamiltonian flow local diffeomorphism?

I am currently reading Arnold's proof of the Darboux theorem in his book on classical mechanics and fail to understand some point. The background So he wants to show that any symplectic form is ...
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Exterior derivative

Let $$\omega = \frac{1}{2} \sum_{i,j} \omega_{i,j} dx_i \wedge dx_j$$ be an antisymmetric form, so i.e. $\omega_{i,j} = - \omega_{j,i}.$ Now, in some lecture notes I found that $$d \omega ...
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Symplectic geometry spectrum

I have a question about a step in the proof of the following theorem from symplectic geometry: The theorem is: Given any ellipsoid $E:=\{ w \in \mathbb{R}^{2n}; \sum_{i,j =1}^{2n} a_{ij}w_iw_j \le ...
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Hamiltonian vector field and symplectic geometry

I want to show the following theorem: For any Hamilton function $H : M \rightarrow \mathbb{R}$ on some symplectic manifold $M$ and symplectomorphism $f : M \rightarrow M$ we have $X_{H \circ f} = ...
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Stokes' theorem and symplectic geometry

Let $V = \mathbb{R}^2,$ as a vector space then the Poincaré invariant is an integral $\int_{\gamma} \theta$ where $\theta = p dx $ is the symplectic 1-form and $\gamma$ a closed curve. Now, it is ...
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Symplectic form on a Hilbert Space is Closed

Let $\mathcal{H}$ be a Hilbert space over $\mathbb{C}$. Define a new vector space, $V$, over $\mathbb{R}$, which has, on the level of sets, $V = \mathcal{H}$ and for scalar multiplication (only with ...
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Two different definitions of a Liouville measure

Ok, I'm currently confused because of two different definitions for the Liouville measure associated to a smooth manifold $M$ of dimension $n$. These are: a) The measure $\mu$ on the cotangent bundle ...
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38 views

Definition of symplectic map

I just started reading on symplectic integrator of Hamiltonian system for my physics project, I don't quite understand some of the basic definitions here(see ...
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Describe the space of solutions to a simple matrix equation

I would like to describe the space of solutions to the following matrix equation. Here $U$ and $V$ are two unknown real matrices with $n$ lines and $p$ columns (i.e. they belong to ...
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77 views

A variational approach to symplectomorphisms

Let $(\Sigma,\omega)$ be a compact symplectic surface, and let $\mathcal{D}$ be the group of diffeomorphisms of $\Sigma$. Is there some known variational approach to determine if an element ...
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1answer
59 views

A function on a space of symplectic forms

Let $M$ be a smooth manifold and $\text{symp}(M)$ be the set of all symplectic forms on $M$. Let $\text{Diff}_{ 0}(M)$ be a connected component of difeomorphisms of $M$. Then, is there an explicit ...
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Differentiating an endomorphism

Let $(M,\rho)$ be a symplectic $2$-dimensional manifold, and let $J$ be a compatible complex structure on $M$, i.e. the symmetric $(0,2)$-tensor $$g(*,*) = \rho(*,J*)$$ is a Riemannian metric. Denote ...
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56 views

Wedge product equality of 2n-forms in 2n+2 dimension

I have a question that seems to me clear but i couldn't prove it. I have a diffeomorphism between the cotangent bundle of the n-sphere and the complex quadric as $$T^*(S^n)\to (S^n)^{\mathbb{C}},\ ...
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Tangent space of the space of compatible complex structures

Let $(M,\omega)$ be a symplectic manifold, and let $\mathcal{J}(M,\omega)$ denote the space of complex structures on $M$ which are compatible with $\omega$. I have been told the following fact: We ...
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Symplectic Geometry of 2-sphere in stereographic projection

I am trying to put the symplectic form of the 2-sphere defined by $\omega_u(v,w) := \langle u,v\times w\rangle,$ where $u \in \mathbb{S}^2$ and $v, w \in T_u\mathbb{S}^2$ in stereographic coordinates ...
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Are the orbits of a symplectic toric manifold the fibers of its moment map?

A symplectic toric manifold, by definition, carries an effective torus action generated by a moment map. The orbits of the torus action are of course contained in the fibers of the moment map, but ...
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293 views

Symplectic reversing diffeomorphisms

Let $(M,\omega)$ be a compact symplectic manifold. Is there a diffeomorphism $f$ on M with $f^{*}\omega =-\omega$?
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Convex boundary of a symplectic manifold

Given a symplectic manifold $(M,\omega)$, suppose that $\partial M$ is of contact type. A Liouville field on a symplectic manifold is a vector field $X$ such that $\mathcal L_X \omega = \omega$. We ...
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36 views

symplectic change of variables

I must prove that the change of variables $\Psi: (p,q)\rightarrow(r,\alpha)$ such that $$q=\sqrt{2r}\cos(\alpha), \qquad p=\sqrt{2r}\sin(\alpha)$$ is symplectic. What I know is: $$\dot{q}=p, \qquad ...
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29 views

symplectic sructure on a ball

We know by Darboux theorem that any symplectic form on a manifold $W^{2n}$ is locally symplectomorophic to the standard symplectic form $dx\wedge dy$ on $R^{2n}$. Is it true that any symplectic form ...
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31 views

Poincaré invariant corresponds to area?

In this paper(equation 34) click me it says that if we have a symplectic egg, then the area of a $(x_i,p_i)$ clone intersected with the egg is given by the poincaré invariant $\int p dx = \int_0^{2 ...
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Carathéodory–Jacobi–Lie theorem

I am studying Analytical Mechanics and want to prove the following theorem: Let be $(M, \omega)$ a sympletic manifold, $U \subset M $ open, $f_1,\ \ldots,\ f_n \in C(U)$ such that 1 $\{f_i,f_j\}=0 ...
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Explicit homotopy equivalence of homogeneous spaces $O(2n)/U(n)$ and $GL(2n,\mathbb{R})/GL(n,\mathbb{C})$

Exercise 2.25 of symplectic topology by McDuff and Salamon asks me to prove that $O(2n)/U(n)$ is homotopy equivalent to $GL(2n,\mathbb{R})/GL(n,\mathbb{C})$. They suggest to use the polar ...
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Parallel $ (1,1) $-forms on compact Kähler manifolds.

Let $ (X,\omega) $ be a compact Kähler manifold. We know one example of a parallel $ (1,1) $-form, namely, $ \omega $ itself. Are there obstructions for the existence of non-vanishing parallel $ (1,1) ...
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Any good resources for learning about the moduli space of symplectic structures on a given manifold?

What I can find on the subject are the papers by Fricke and the Habermanns: http://www.researchgate.net/publication/227336993_On_the_geometry_of_moduli_spaces_of_symplectic_structures and ...
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The Classification of almost complex structures (almost) tamed by a quadratic form

Preamble I am currently dealing with the almost complex structures associated with a non-degenerate quadratic form. In particular, I am interested the size of the almost complex structures as a ...
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What is a local invariant?

Let $(M,g)$ be a Riemannian manifold. Then, it is usually said that $M$ has local invariants associated to $g$. For example, the curvature of the Levi-Civita connection associated to $g$. My question ...
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About Lefschetz fibration signature

Does there exists a Lefschetz fibration over $S^2$ for any given number admitting it as a signature? I think it is not possible so I need an counter example.
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rank of the symplectic form

This is a general question about ranks of differential forms. I read in a book the phrase "symplectic form has constant rank..." I understand that the symplectic form is a nondegenerate differential ...
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covering finite Dimensional vector space

can a finite dimensional symplectic vector space over finite field be covered with mutually transversal Lagrangian planes(maximal Isotropical Subspaces )?
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symplectic manifolds

I know sometimes they use advanced methods to prove a given 4-manifold is not symplectic. for instance by Seiberg-Witten theory. But for a manifold to be symplectic we just need to check that there is ...
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Why spheres are not symplectic manifolds?

Reading some books on diferential geometry, a found that $S^{2n}$ (with $ n>1$) are not symplectic manifolds. They say it's because the de Rham cohomology of this spheres are R, but I do not ...
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Skew-symmetric non-degenerate bilinear form

If we do symplectic linear algebra on a finite-dimensional vector space $V$, then what does $$\omega(v,w) \neq 0$$ or $$\omega(v,w) = 0$$ actually tell us about the vectors $v,w$? ($\omega$ is the ...
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Pullback 1-differential form

Let $(x_0,x'_0) \in \mathbb{R}^2$ be initial data for the Euler Lagrange equation with some given Lagrangian $L: \mathbb{R}^2 \rightarrow \mathbb{R}.$ Then $F^t$ is the flow that maps the initial ...
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Momentum a cotangent vector?

Imagine we have a particle described by $x \in M$, where $M$ is some manifold, then it is very intuitive I think that a velocity is an element of the tangent space at $x$, so $x' \in T_{x}M.$ Thus, by ...
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Why is the $ n $ - exterior power of a symplectic form does not vanish?

Let $ V $ be a vector space. Could someone explain to me why is : Any $ \Omega \in \bigwedge^{2} ( V^* ) $ is of the form $ \Omega = e_{1}^* \wedge f_{1}^* + \dots + e_{n}^* \wedge f_{n}^* $ where ...
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Relative line bundle along divisor $D$

Let $X$ and $B$ be a compact Kahler manifolds and $\pi:X\to B$ be a holomorphic surjective map and $D$ be a divisor in $X$ how can we define relative canonical line bundle on $B$ along a divisor $D$? ...
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Can you have a “real” decomposition of differential forms on a symplectic manifold?

With a choice of (almost) complex structure on a symplectic (Kahler) manifold, has anyone thought of how or what it means to globally define "real" versions of the Dolbeault operators? i.e. Something ...
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Coordinate free definition of the canonical one-form

There is apparently a naturally defined one-form on the cotangent bundle of a smooth manifold $M$: We have the cotangent bundle $\pi:T^*M \rightarrow M$; taking its derivative gives $d \pi:TT^*M ...
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What happens to symplectic basis if bilinearity condition is weak

Let $B:V\times V \rightarrow K$ be a (weak!) bilinear form where $K$ is a finite field with base field $F$ and $V$ a vector space over $K$. Let $u,v \in V$ and $\lambda \in F (!)$ $B(u + v, w) = B(u, ...
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Fibered product of symplectic fiber bundles

Let $P_{1}\to B$ and $P_{2}\to B$ be smooth fiber bundles over the same base manifold $B$, and let us assume that the total spaces $(P_{1},\omega_{1})$ and $(P_{2},\omega_{2})$ are symplectic ...
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symplectic surfaces in 4-manifolds

Is it true that for any surface in a symplectic 4-manifold $X$, representing a given homology class of $H_2(X)$, we can assume it is symplectic? I mean for each second homology class, can we find a ...
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Symplectic lie algebra

Can anyone explain me why, in the symplectic lie algebra, which is defined as $ sp(n)=\{X \in gl_{2n}:X^tJ+JX=0\}$ where $J=\begin{pmatrix} 0 & I \\ -I & 0 \\ ...
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Are the following Hamiltonian actions?

Let $(x,y)$ be the coordinate of $\mathbb{C}^2 \subset \mathbb{P}^1\times \mathbb{P}^1$. Is the $S^1$ action on $\mathbb{P}^1\times \mathbb{P}^1$ given by $$ t\cdot(x,y)=(tx,t^{-1}y) $$ Hamiltonian? ...
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According to Liouville's theorem, why is the measure on an energy-surface different from the measure on the phase space in general

I recently read Khinchin's derivation of Liouville's theorem. I was able to follow the math for the most part, however I was hoping for an intuitive understanding about why the form of the measure on ...
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The meaning of variables and derivations in Souriau's book

As far as I see, Souriau is using unconventional notions in his book "Structure of Dynamical Systems". He explains these notions in §2. of Chapter I, but it is a puzzle for me. Mainly because he ...