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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Canonical bundle of the Lagrangian Grassmannian

I'd like to compute the canonical bundle of the Lagrangian Grassmannian $\mathbb{LG}_n$, the set of Lagrangian subspaces of dimension $n$ of a vector space together with fixed symplectic bilinear ...
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Existence of symplectomorphism that preserves submanifolds

I have the following question: Let $(M,\omega)$ be a symplectic manifold and let $N_1$ and $N_2$ be submanifolds of $M$ such that there is a diffeomorphism $\psi:M \rightarrow M$ such that $\psi(N_1) ...
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Constructing symplectic structure on $T^*M$

I read the picture below, but I don't know how to get the equation above red line. Whether by using $T_{\xi_x}(T^*M)\cong T^*_xM$ ?But which isomorphism should be choice ? Then , how to check the ...
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Overview of Geometric analysis [closed]

Can anyone tell me what geometric analysis is about? After reading some articles I have a view that it uses PDE extensively for geometric problems. Am I right in this point? Also what kind of ...
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Question about the lattice of the O'Grady 6-dimensional example

This is perhaps a silly question, but I could not find neither a reference nor an answer by myself. Let $X=\widetilde{M}_{v}$ be the $6$-dimensional irreducible holomorphic symplectic manifold ...
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Cartesian product of $\mathbb{S}^1$ is symplectic

Prove that the Cartesian products of $\mathbb{S}^1$ for $2n$ times is a symplectic manifold. I have just studied the concepts of symplectic manifold in the class of analytical mechanics. I have not ...
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Looking for topics in symplectic geometry suitable for a 1 hour talk

I am a master2 student and I am looking for a topic in symplectic geometry to make a 1 hour presentation with. I only had a short introduction course to symplectic geometry so subjects shouldn't be ...
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52 views

Show that $\widetilde{f}$ is a nondegenerate map?

Noted by $V, W$ two vectors spaces over the same field $K$ of finite dimensions. Let $f:V\times V\rightarrow W$ a degenerate map. I would show that $$\widetilde{f}:\widetilde{V}\times \widetilde{V}\...
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Is Floer homology always isomorphic to the singular homology of some space?

After I studied Morse homology, I'm now studying the following Floer homology theories : 1) Symplectic Floer homology ; 2) Floer homology of lagrangians ; 3) Heegard-Floer homology ; ...
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Example of a degenerate bilinear map?

I seek an example of a nonzero $\Bbb{R}$-bilinear map $f:V\times V\rightarrow W$ on a vector space $V$ (s.t: $\dim V<\infty$, $\dim W<\infty$) such that it is degenerate map, where $V$ and $W$ ...
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the symplectic version of Gram-Schmidt process and one application of it.

I am trying to understand the following proposition: cf. McDuff and Salamon, Introduction to Symplectic Topology(second edition), Corollary 2.4,page 40 One can assume $\omega_0 =\sum_i dx_i \...
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Bundle isomorphism $\Phi : TM \oplus T^*M \to T(T^*M)$.

Prove that there is a bundle isomorphism $\Phi : TM \oplus T^*M \to T(T^*M)$ which identifies the summand $T^*M$ with the vertical vectors. If $\omega_{can}$ is the canonical symplectic ...
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Geodesic flow generated by Riemannian distance function

This is an exercise in AC da Silva's Lectures onn Symplectic Geometry; I am having trouble showing the following. $(X,g)$ is a geodesically complete manifold, and $f: X \times X \to \mathbb{R}$ is ...
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45 views

Hamiltonian Mechanics and the Symplectic Category

Are canonical transformations (in the sense of Hamiltonian mechanics) morphisms for a certain category? They seem to fit the archetypal description of morphisms being "structure-preserving maps". ...
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Reference request in contact geometry.

I am looking for an introductory book to contact geometry, as clear and detailed as possible. Thank in advance.
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On a Lie group $G$, is $\{v-Ad_gv\mid v\in\mathfrak{g},g\in G\}=[\mathfrak{g},\mathfrak{g}]$?

On a Lie group $G$, is $\{v-Ad_gv\mid v\in\mathfrak{g},g\in G\}=[\mathfrak{g},\mathfrak{g}]$? This question is inspired by noting that if we have a Hamiltonian Lie group action $G\curvearrowright (M,\...
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decomposition of general symplectic matrix

Suppse $S$ be a $2n \times 2n $ symplectic matrix $$ S = \left( \begin{array}{cc} A & B\\ C & D \end{array} \right) . $$ By definition, $S^tJS$=J, where $$J = \left( \begin{array}{cc} 0 &...
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53 views

Are there characteristic classes for symplectic vector bundles?

Given a real vector bundle, say the tangent bundle of a manifold, some obstructions to this being the underlying real bundle of a complex bundle come from characteristic classes. These can prove the ...
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Why are symplectic manifolds and Riemannian manifolds so different?

They seem superficially similar in some ways 1) both have a given two tensor on the tangent space 2) if we choose a hamiltonian function for the symplectic manifold then both give a canonical ...
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Hyperbolicity without ergodicity?

I have a question concerning the ergodic properties of hyperbolic Hamiltonian flows. Let $\Phi_{H}^{t}$ be a Hamiltonian flow on a symplectic manifold $\mathcal{M}$. If $\Phi_{H}^{t}$ is Anosov on a ...
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Kernel of $\omega^\#$ is $k$-dimensional

Let $M$ be a smooth manifold with coordinates $\{q^i\}_{i=1}^n$ .The variables $(q^i,p_i)$ are coordinates on the cotangent space $\Omega=T^*M$. Any cotangent space carries a natural one-form $\tilde{\...
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What is the smoothness of a family of diffeomorphisms $t\mapsto \psi_t \in \text{Diff}(M)$ ? And how to interpret it intuitively?

First of all, we have to give the group $\text{Diff}(M)$ of all diffeomorphisms on $M$ a smooth-manifold structure. (To see this, it may be helpful to consider a easier problem: how to give the group $...
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How do we give G/T a symplectic structure

I am new in those staff and I can't find anything introductory explaining those stuff. I am interested in the following. Given $G$ a compact Lie group and consider it's maximal torus $T$. Then I have ...
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References on the moduli space of flat connections as a symplectic reduction

In their Yang Mills equations over Riemann surfaces paper, Atiyah & Bott famously remark that the moduli space of flat connections on a principal bundle over a compact orientable surface may be ...
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Composition of symplectomorphisms not a symplectomorphism?

Given $R^{2n}=C^{n}$ with its standard symplectic form $\Omega$, and v an arbitrary vector, the individual transvections $\tau(p)=p+\Omega(v,p)v$ and $\sigma(p)=p+\Omega(iv,p)iv$ preserve the ...
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Volume of “the complex projective space” of a certain radius.

Consider the circle action on $\mathbb C^n$ given by $(e^{it},z)\to e^{it}z$. A moment map for this action is $J:\mathbb C^n\to\mathbb R:z\to -\frac{1}{2}|z|^2$. Let $M_l=J^{-1}(-\frac{l}{2})/U(1)$ ...
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Why is the tangent space to the orbit through $p\in\mu^{-1}(0)$ an isotropic subspace of $T_pM$?

I'm reading symplectic geometry notes by Ana Cannas da Silva. The set up is a Hamiltonian action $G\curvearrowright(M,\omega)$ of a Lie group $G$ on the symplectic manifold $(M,\omega)$, with moment ...
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The fact that surface of spherical segment only depends on its height follows from symplectic geometry

It is quite quite well known that the surface of the piece of a sphere with $z_0<z<z_1$ for some values of $z_0,z_1$ is given by $ S = 2\pi R (z_1-z_0) $. So this surface area only depends on ...
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1answer
127 views

Trouble understanding proof of this proposition on contact type hypersurfaces

I have finally started working on my thesis. I am reading the first reference book, which is Dusa McDuff, D. Salamon, Introduction to Symplectic Topology. It's a tough struggle, given my not-too-great ...
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Given two linear symplectic 4-tori. When are they symplectomorphic?

What are symplectic invariants that can be computed for a linear symplectic 4-torus? The symplectic volume is the simplest one. Is it possible to have something else?
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Pushforward of Liouville measure on configuration space

Say I have $M_1$ a 3-dimensional compact Riemannian manifold, and $M=M_1^{n}$ the product manifold representing n particles on $M_1$. I can identify $TM$ with $T^*M$ via the metric $g$ and then the ...
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Connectedness of the level sets of Mose-Bott functions

I am reading the proof by McDuff and Salamon of the connectedness of the level sets of Morse-Bott functions with index and coindex different from $1$: connectedness of level sets A smooth function $f:...
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Problems understanding this proof

$\textbf{Theorem 3.5.10}$ (Arnol'd $[1]$). Suppose $(M,\sigma)$ is a symplectic manifold of dimension $2n$, let $f_1,...,f_n$ be an involution on $M$, and finally assume that the Hamilton fields $H_{...
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Formula about time derivative of pushforward of family of forms: where is it from?

Proving Darboux's theorem, Hofer-Zehnder try to find, given $\omega$ a closed nondegenerate 2-form and $\omega_0$ the canonical symplectic form, a family of diffeomorphisms $\phi^t$ such that for all $...
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Intuition behind variational principle

Hofer-Zehnder, in section 1.5, proves that every Hamiltonian field on a strictly convex compact regular energy surface carries a periodic orbit. I have understood the proof. What I am wondering about ...
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Passage in a proof from Hofer-Zehnder

The proof I'm referring to is to the following theorem. Assume $S$ is a compact regular and strictly convex energy surface for the Hamiltonian field $X_H$ in $\mathbb{R}^{2n}$. Then $S$ carries a ...
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Additional References — Symplectic Geometry

Please forgive me if I should ask this question somewhere else. If so, let me know and I will do so. I have never asked a question of this nature before, and so am unsure where an appropriate place ...
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Wedge Products with the Symplectic Form

Let $ \omega $ denote the symplectic form on $ \mathbb{R}^{2n} $, namely $ \omega = dx_1 \wedge dy_1 + \cdots + dx_n \wedge dy_n $. Then let $ T $ be the linear map from $ (n-1) $- forms to $ (n+1) $-...
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Momentum Map-Submersion

Let $(M,\omega)$ be a symplectic manifold and $G$ a Lie group acting hamiltonian on $M$, such that the momentum map $\Phi \colon M \to \mathfrak{g}^*$ is $G$-equivariant w.r.t. the coadjoint-action on ...
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Symplectic form on $\mathbb R ^{2n}$

What are all symplectic form $\omega$ on $\mathbb R^{2n}$. Where, a ''symplectic bilinear form'' on $\mathbb R^{2n}$ is . a bilinear form: a map $\omega: \mathbb R^{2n}\times \mathbb R^{2n}\to \...
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Symplectic form on $T^ ∗X$

If $\mu$ is any closed 2-form on a manifold $X$, then $d\alpha_X + π^∗\mu$ is also a symplectic form on $T^ ∗X$, where $\alpha_X$ is tautological one-form and $\pi:T^*X\to X$ is projection. In fact, ...
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Symplectic Chart

I was reading the article "Symplectic structures on Banach manifolds" by Alan Weinstein. In this article there is one theorem, which is as following: If $B$ is a zero neighborhood in Banach space. ...
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How to keep symplecticity of a diffeomorphism after a coordinate rescaling and Taylor series expansion?

Let's take some, implicitly written, symplectic diffeomorphism $F$ of $\mathbb{R}^{2n}$, let it preserve the (possibly non-standard) symplectic form $\omega$. Suppose I introduce a small parameter $\...
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Are curvature forms in complex line bundles symplectic

I know that the curvature form $F_\nabla$ of a connection $\nabla$ in a complex line bundle $L \to B$ is presymplectic (i.e. antisymmetric and closed). Does it also have to be non-degenerate, i.e ...
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Darboux theorem for symplectic manifold of degree 2

Given $p \in M$ and $\alpha \in \Omega^1(M)$ with $\alpha_p \neq 0$, show that there exists a neighbourhood $U$ of $p$ in $M$ and $f,g \in C^{\infty}(U)$ such that $\alpha|_U = f dg$. To show this ...
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Specifics on the Williamson normal form algorithm

I'm looking at the algorithm for Williamson normal form for symplectic diagonalization of positive-definite symmetric real matrices, given on pp.24 here: https://www.ime.usp.br/~piccione/Downloads/...
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Mirror Symmetry of Elliptic Curve

I'm a little bit unsure about the mirror symmetry statement for elliptic curves; specifically, how the flipping of the Kähler and complex moduli works. Perhaps I should say at the outset, the reason ...
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1answer
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How to derive the standard symplectic form on a 2-sphere in cylindrical polar coordinates?

I have already know that at a point $p\in S^2$ with $u,v$ the tangent vectors at $p$. Then the standard symplectic form is $\omega_p(u,v) :=\langle p,\,u\times v\rangle$ where $u\times v$ is the outer ...
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Exercise about Lagrangian submanifolds

I am trying to solve the following exercise: Let $(M,\omega)$ be a symplectic manifold and $L$ a compact Lagrangian submanifold such that $H^{1}(L)=0$. Let $\{L_{t}\}_{t\in(-1,1)}$ be a smooth family ...