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Hamiltonian systems, symplectic flows, classical integrable systems

5 votes
Accepted

Embeddings of magnetic cotangent bundles over surfaces into closed symplectic 4-manifolds

This can always be done. Let's first treat the case when $\Sigma$ is not a torus. Then take any symplectic $4$-manifold $(M,\omega)$ where $\Sigma$ can be embedded as a Lagrangian surface. Now, take a …
Dmitri Panov's user avatar
  • 28.9k
3 votes

Comparing the minimal Chern number and the cup-length of a symplectic manifold

I had a look at the paper of Givental, https://math.berkeley.edu/~giventh/papers/tor.pdf and don't see this statement... If this statement were true, Conjecture 6.1 of Eliashberg from 2015 would be …
Dmitri Panov's user avatar
  • 28.9k
6 votes

Contactomorphisms have in general no fixed points

I hope that the following answers some parts of the question. 1) a) It is not true that a generic contactomorphim doesn't have fixed points. For example, let $M$ be the three-dimensional torus that …
Dmitri Panov's user avatar
  • 28.9k
3 votes
Accepted

Hamiltonian $S^1$ actions with isolated fixed points

Nick Lindsay and have just proved that such a manifold indeed exists. And surprise, surprise, this is Tolman's manifold. See Theorem 1.3 and Corollary 1.4 of our paper: https://arxiv.org/abs/1912.027 …
Dmitri Panov's user avatar
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2 votes
Accepted

Symplectic structure vanishing simultaneously on two totally real subspaces

I'll give a positive answer for two generic totally real planes in $\mathbb C^2$. I believe this generalises to larger $n$, though I don't prove it - just give a possible plan of a proof with one step …
Dmitri Panov's user avatar
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2 votes

Large isometry groups of Kaehler manifolds

A positive answer to this question should follow from Berger's holonomy classification and the following statement, which I believe is correct: Statement. For any dimension $n$ there exists a positi …
Dmitri Panov's user avatar
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2 votes
Accepted

Star-shaped domain in $\mathbb{C}P^2$

One way to prove this is as follows. First, from the assumption $B(1)\subset \mathbb C^2$ and the centre of $B(1)$ is $(0,0)$. Now we need the following two claims. Claim 1. Any straight geodesic u …
Dmitri Panov's user avatar
  • 28.9k
9 votes
Accepted

Half-dimensional torus fibration vs Lagrangian torus fibration

This doesn't need to hold. For example, if one takes a $(T^4,\omega)$ with a constant symplectic structure $\omega$, in order for it to have a fibration by Lagrangian tori one should be able to find a …
Dmitri Panov's user avatar
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3 votes
Accepted

Uniqueness of a compatible Kahler-Einstein structure on a symplectic manifold?

Concerning 2) one can, of course, take the product of two curves of higher genus to get a counter-example. In general, to have a statement as you want, one should look for rigid complex surfaces of ge …
Ben McKay's user avatar
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11 votes

Manifolds distinguished by Gromov-Witten invariants?

Here is an answer to the REFINED question given to me by Richard Thomas. In this refined version one looks for an example such that the cohomology classes of two symplectic forms coincide. In a late …
Dmitri Panov's user avatar
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14 votes
Accepted

How Many 4-Manifolds are Symplectic?

I have to apologize, in fact the answer to the second question is still unknown. Namely, up to now all known symplectic manifolds of dimension 4 that have negative Euler characteristic are blow ups of …
Dmitri Panov's user avatar
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5 votes
Accepted

Smooth projective toric varieties which are quotients of product of spheres and torii by a f...

Let us consider the case of toric varieties of real dimension $4$ and prove they can not be represented as such a quotient unless they have second Betti number $1$ or $2$. Proof. Let us introduce …
Dmitri Panov's user avatar
  • 28.9k
2 votes

Hamiltonian actions and contractible loops

There are counter-examples, hope they answer your question completely, just take any non-simply connected $G$ and consider its action on $T^*G$. The simplest case is: Let $M$ be the cylinder $S^1\tim …
Dmitri Panov's user avatar
  • 28.9k
9 votes

Reasons for the Arnold conjecture

In a certain sense, symplectic geometry (or safer to say symplectic topology) as we know it now was not existing before Arnold formulated these conjectures. So many would say that Arnold conjectures g …
Dmitri Panov's user avatar
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2 votes
Accepted

Isometric embedding of a real-analytic Riemannian manifold in a compact Kähler manifold

I think the answer to your question should be positive and below is a sketch of what should work (I think). Any real analytic manifold can be realised as the real part of a complex projective manifol …
Dmitri Panov's user avatar
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