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Hamiltonian systems, symplectic flows, classical integrable systems

4 votes
Accepted

symplectic volume of embedded J-holomorphic disk

Unless I'm misunderstanding what you're asking, the answer is surely no...consider for instance $\mathbb{C}P^n$ with its standard symplectic and complex structures. This admits embedded $J$-holomorph …
Mike Usher's user avatar
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5 votes
Accepted

How many Symplectic Structures on CP^n?

One of the headline consequences of Taubes' work on Seiberg-Witten theory on symplectic four- manifolds was that the standard symplectic form on $\mathbb{C}P^2$ is the unique one (up to scale, of cour …
Mike Usher's user avatar
  • 2,927
6 votes
Accepted

Lagrangian submanifold containing a curve

Yes, such a Lagrangian submanifold does exist. The isotropic neighborhood theorem (see for instance p. 24 of Weinstein's Lectures on Symplectic Manifolds), together with the fact that all symplectic …
Mike Usher's user avatar
  • 2,927
11 votes

Special Hamiltonian diffeomorphisms

Can't you get such an obstruction by looking at periodic points? It's not difficult to show that generic Hamiltonian diffeomorphisms have only isolated fixed points, and indeed only isolated periodic …
Mike Usher's user avatar
  • 2,927
7 votes

Does symplectic cohomology admit a natural Batalin-Vilkovisky algebra structure?

Yes it does. Geometrically the BV operator is gotten by considering the parametrized moduli space of solutions to the Floer equation on the cylinder obtained by rotating one end of the cylinder. Thi …
Mike Usher's user avatar
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10 votes
Accepted

symplectic structure of tangent bundle of $\mathbb{S}^{n-1}$

Here is a formula for an explicit symplectomorphism $F$ from $T^*S^{n-1}$ to the affine quadric $\{\sum z_{j}^{2}=1\}$ in $\mathbb{C}^n$: $$ F(p,q) = \left(\frac{1+\sqrt{1+4|p|^2}}{2}\right)^{1/2} …
Mike Usher's user avatar
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4 votes
Accepted

What are some conserved quantities of Poisson brackets?

My impression is that for most choices of H this is a hard question. In general, the largest possible cardinality of a set of independent Poisson commuting functions on a 2n-dimensional symplectic ma …
Mike Usher's user avatar
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3 votes
Accepted

Examples of symplectic non-Kahler classes.

One sort of example arises from the fact that if one starts with a Kahler form $\omega$ (which represents a class of type (1,1) in the Hodge decomposition by definition of a Kahler form), then if $\ph …
Mike Usher's user avatar
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2 votes
Accepted

Homotopy groups of the blow-ups and monotone symplectic manifolds

Write $X$ for the manifold in question (i.e. the symplectic blowup of the unit disc bundle in the cotangent bundle of a surface $\Sigma$). If you're interested just in monotonicity, what's relevant is …
Mike Usher's user avatar
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7 votes
Accepted

Symplectic blow-up

I don't know a place where this is written up explicitly, but it's not hard as soon as one has an appropriate standard model for a neighborhood of a symplectic manifold for use in the Weinstein Neighb …
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21 votes
Accepted

Manifolds distinguished by Gromov-Witten invariants?

The examples in Ruan's paper "Symplectic topology on algebraic 3-folds" (JDG 1994) seem to qualify: take any two algebraic surfaces V and W which are homeomorphic but such that V is minimal and W isn' …
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7 votes

Compact Kaehler manifolds that are isomorphic as symplectic manifolds but not as complex man...

In case anybody is curious, there are still examples of (1) even if one replaces the requirement that the complex manifolds be nonisomorphic with the requirement that they be not even deformation equi …
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13 votes
Accepted

Why (and whether) is any smooth embedded torus in R^4 isotopic to an embedded Lagrangian torus?

Whoever told you that any embedded torus in R4 is isotopic to a Lagrangian torus was sorely mistaken. Luttinger (JDG 1995) observed the following: The manifolds obtained by doing certain Dehn-type su …
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9 votes

Examples of non-Kahler compact symplectic manifolds.

There are lots of simply-connected four-dimensional examples in Gompf's symplectic sum paper paper which are shown to be non-Kahler by virtue of violating the Noether inequality (see Theorem 6.2). Th …
13 votes
1 answer
1k views

Gromov-Witten invariants counting curves passing through two points

Let us say that a closed symplectic manifold $X$ is $GW_g$-connected if there is a nonvanishing Gromov-Witten invariant of the form $GW_{g,n}^{X,A}(\beta,point, point,\alpha_3,\ldots,\alpha_n)$ --in o …
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