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Hamiltonian systems, symplectic flows, classical integrable systems

9 votes
1 answer
633 views

"Nice" way to compute the signature of a toric manifold?

Is there a "nice" way to compute the signature of a smooth toric manifold of even complex dimension in terms of the moment polytope? By signature I mean in the sense of topology (see https://en.wikipe …
Nick L's user avatar
  • 6,995
11 votes
1 answer
415 views

A theorem about the symplectic geometry of projective bundles

I am trying to understand the following theorem about symplectomorphisms of projective bundles. Theorem 1.5 of "Characteristic Classes in Symplectic Topology" A.G. Reznikov. Selecta Mathematica, volum …
Nick L's user avatar
  • 6,995
3 votes
0 answers
123 views

An inequality for symplectic manifolds

Question: Is there a closed symplectic manifold satisfying the following? $$|Td(M)| > \sum_{i \in \mathbb{Z}} b_{i}(M) $$ here $Td(X)$ is the Todd genus of $M$ i.e. the integral of the Todd class on …
Nick L's user avatar
  • 6,995
5 votes
0 answers
112 views

symplectic sum of two copies of $Bl_{p}(\mathbb{CP}^{2})$

Let $M^{4}= \mathbb{P}(\mathcal{O} \oplus \mathcal{O}(1))$ and $\omega$ the symplectic form on $M^{4}$ given by the anticanonical polarisation. Suppose we form a symplectic (Gompf) sum of two copies …
Nick L's user avatar
  • 6,995
2 votes
0 answers
83 views

Does this condition imply symplectic birational cobordism?

From the definition of symplectic birationality given here (https://arxiv.org/pdf/0906.3265.pdf, Definition 2.1), two compact symplectic $2n$-manifolds $(M_{1},\omega_{1}),(M_{2},\omega_{2})$ are call …
Nick L's user avatar
  • 6,995
15 votes
1 answer
818 views

symplectic form on an algebraic family

I know that smooth Fano varieties over $\mathbb{C}$ may be classified into a finite number of families in each dimension (1 in dimension 1, 10 in dimension 2, 105 in dimension 3 ...). I am intereste …
Nick L's user avatar
  • 6,995
2 votes
1 answer
122 views

Hamiltonian Group action with infinitely many stabiliser types

What is an example of a connected symplectic manifold $(M,\omega)$, with a Hamiltonian action of $G = U(1) =S^{1}$ with infinitely many stabiliser types? Infinitely many stabiliser types means that i …
Nick L's user avatar
  • 6,995
8 votes
1 answer
201 views

Todd genus of symplectic $4$-manifolds a smooth invariant?

Suppose that $(M_{1},\omega_{1})$ and $(M_{2},\omega_{2})$ are compact symplectic $4$-manifolds, that are (oriented) diffeomorphic. Is it true that the Todd genus ($\frac{1}{12} (c_{1}^{2} + c_{2})(M_ …
Nick L's user avatar
  • 6,995
11 votes
0 answers
532 views

Third cohomology of symplectic $6$-manifolds

Suppose that $A$ is a finitely generated abelian group with even rank and without $2$-torsion. Does there exist a compact symplectic $6$-manifold $(M,\omega)$ such that $A$ Is isormorphic to $H^{3}(M, …
Nick L's user avatar
  • 6,995
3 votes
1 answer
423 views

Example of finite order symplectomorphism which is not an automorphism

Let $X$ be a smooth projective variety over $\mathbb{C}$. Consider the Kahler structure $(J,g,\omega)$ on $X$ induced by the Fubini-Study metric. Let $Symp(X,\omega)$ be the group of symplectomorphism …
Nick L's user avatar
  • 6,995