Eugene Lerman
We describe a contact analog of the symplectic cut construction. As an application we show that the group of contactomorphisms for a particular overtwisted contact structure on the three sphere contains countably many nonconjugate two tori.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
继续探索
In a recent preprint Yael Karshon showed that there exist non-conjugate tori in a group of symplectomorphisms of a Hirzebruch surface. She counted them in terms of the cohomology class of the symplectic structure. We show that a similar phenomenon exists in the contactomorphism groups of pre-quantum circle bundles over Hirzebruch surfaces. Note that the contact structures in question are fillable. This may be contrasted with an earlier paper where we showed that there are infinitely many non-conjugate tori in the contactomorphism groups of certain overtwisted lens spaces (Contact cuts, Israel …
By a theorem of Banyaga the group of diffeomorphisms of a manifold $P$ preserving a regular contact form $α$ is a central $S^1$ extension of the commutator of the group of symplectomorphisms of the base $B = P/S^1$. We show that if $T$ is a Hamiltonian maximal torus in the group of symplectomorphism of $B$, then its preimage under the extension map is a maximal torus not only in the group $\Diff(P, α)$ of diffeomorphisms of $P$ preserving $α$ but also in the much bigger group of contactomorphisms $\Diff (P, ξ)$, the group of diffeomorphism of $P$ preserving the contact distribution $ξ= \ker α$…
I describe a general scheme which associates conjugacy classes of tori in the contactomorphism group to transverse almost complex structures on a compact contact manifold. Moreover, to tori of Reeb type whose Lie algebra contains a Reeb vector field one can associate a Sasaki cone. Thus, for contact structures of K-contact type one obtains a configuration of Sasaki cones called a bouquet such that each Sasaki cone is associated with a conjugacy class of tori of Reeb type.
We show the existence of elements of infinite order in some homotopy groups of the contactomorphism group of overtwisted spheres. It follows in particular that the contactomorphism group of some high dimensional overtwisted spheres is not homotopically equivalent to a finite dimensional Lie group.
We prove that on overtwisted contact manifolds there can be no positive loops of contactomorphisms that are generated by a $C^0$-small Hamiltonian function.
In this paper we study the groups of contactomorphisms of a closed contact manifold from a topological viewpoint. First we construct examples of contact forms on spheres whose Reeb flow has a dense orbit. Then we show that the unitary group U(n+1) is homotopically essential in the group of contactomorphisms of the standard contact sphere S^(2n+1) and prove that in the case of the 3-sphere the contactomorphism group is in fact homotopy equivalent to U(2). In the second part of the paper we focus on the group of strict contactomorphisms -- using the framework of Chern-Weil theory we introduce an…
For certain contact manifolds admitting a 1-periodic Reeb flow we construct a conjugation-invariant norm on the universal cover of the contactomorphism group. With respect to this norm the group admits a quasi-isometric monomorphism of the real line. The construction involves the partial order on contactomorphisms and symplectic intersections. This norm descends to a conjugation-invariant norm on the contactomorphism group. As a counterpoint, we discuss conditions under which conjugation-invariant norms for contactomorphisms are necessarily bounded.
A positive contactomorphism of a contact manifold $M$ is the end point of a contact isotopy on $M$ that is always positively transverse to the contact structure. Assume that $M$ contains a Legendrian sphere $Λ$, and that $(M,Λ)$ is fillable by a Liouville domain $(W,ω)$ with exact Lagrangian $L$ such that $ω|_{π_2(W,L)}=0$. We show that if the exponential growth of the action filtered wrapped Floer homology of $(W,L)$ is positive, then every positive contactomorphism of $M$ has positive topological entropy. This result generalizes the result of Alves and Meiwes from Reeb flows to positive cont…
For a closed connected manifold N, we establish the existence of geometric structures on various subgroups of the contactomorphism group of the standard contact jet space J^1N, as well as on the group of contactomorphisms of the standard contact T*N \times S^1 generated by compactly supported contact vector fields. The geometric structures are biinvariant partial orders (for J^1N and T*N \times S^1) and biinvariant integer-valued metrics (T*N\times S^1 only). Also we prove some forms of contact rigidity in T*N \times S^1, namely that certain (possibly singular) subsets of the form X \times S^1…
We build homogeneous quasi-morphisms on the universal cover of the contactomorphism group for certain prequantizations of monotone symplectic toric manifolds. This is done using Givental's nonlinear Maslov index and a contact reduction technique for quasi-morphisms. We show how these quasi-morphisms lead to a hierarchy of rigid subsets of contact manifolds. We also show that the nonlinear Maslov index has a vanishing property, which plays a key role in our proofs. Finally we present applications to orderability of contact manifolds and Sandon-type metrics on contactomorphism groups.
We prove a version of Sandon's conjecture on the number of translated points of contactomorphisms for the case of prequantization bundles over certain closed monotone symplectic toric manifolds. Namely we show that any contactomorphism of such a prequantization bundle lying in the identity component of the contactomorphism group possesses at least $N$ translated points, where $N$ is the minimal Chern number of the symplectic toric manifold. The proof relies on the theory of generating functions coupled with equivariant cohomology, whereby we adapt Givental's approach to the Arnold conjecture f…
A Note on Somewhere Positive Loops of Contactomorphisms
本文研究了接触流形中非空闭合子集上正的可缩循环接触同构映射，通过辛同调和最近引入的接触准测度结果，证明其补集在接触几何中有重要意义。
On the space of cone geodesics and positive paths of contactomorphisms
本文研究了锥流形空间作为光滑接触流形的结构，并建立了球面余切丛中接触同构正路径与全局超曲面锥结构的对应关系。
We show that the $L^{\infty}$-norm of the contact Hamiltonian induces a non-degenerate right-invariant metric on the group of contactomorphisms of any closed contact manifold. This contact Hofer metric is not left-invariant, but rather depends naturally on the choice of a contact form $α,$ whence its restriction to the subgroup of $α$-strict contactomorphisms is bi-invariant. The non-degeneracy of this metric follows from an analogue of the energy-capacity inequality. We show furthermore that this metric has infinite diameter in a number of cases by investigating its relations to previously de…
A point q in a contact manifold is called a translated point for a contactomorphism ϕ, with respect to some fixed contact form, if ϕ(q) and q belong to the same Reeb orbit and the contact form is preserved at q. In this article we discuss a version of the Arnold conjecture for translated points of contactomorphisms and, using generating functions techniques, we prove it in the case of spheres (under a genericity assumption) and projective spaces.
We prove that some paths of contactomorphisms of $\mathbb{R}^{2n} \times S^1$ endowed with its standard contact structure are geodesics for different norms defined on the identity component of the group of compactly supported contactomorphisms and its universal cover. We characterize these geodesics by giving conditions on the Hamiltonian functions that generate them. For every norm considered we show that the norm of a contactomorphism that is the time-one of such a geodesic can be expressed in terms of the maximum of the absolute value of the corresponding Hamiltonian function. In particular…
In his 1992 article on generating functions Viterbo constructed a bi-invariant metric on the group of compactly supported Hamiltonian symplectomorphisms of R^2n. Using the set-up of arXiv:0901.3112 we extend the Viterbo metric to the group of compactly supported contactomorphisms of R^2n x S^1 isotopic to the identity. We also prove that the contactomorphism group is unbounded with respect to this metric.
On certain $C^0$-aspects of contactomorphism groups
本文研究了接触同胚群$C^0$-拓扑相关问题，揭示了Rokhlin性质与接触非挤压的联系，定义了新共轭不变范数，证明了Sandon谱范数的$C^0$-局部有界性并将其推广至接触同胚映射。
We construct a natural prequantization space over a monotone product of a toric manifold and an arbitrary number of complex Grassmannians of 2-planes in even-dimensional complex spaces, and prove that the universal cover of the identity component of the contactomorphism group of its total space carries a nonzero homogeneous quasi-morphism. The construction uses Givental's nonlinear Maslov index and a reduction theorem for quasi-morphisms on contactomorphism groups previously established together with M. Strom Borman. We explore applications to metrics on this group and to symplectic and contac…
We define a Lorentzian distance function on the group of contactomorphisms of a closed contact manifold. This distance function is continuous with respect to the Hofer norm on the group of contactomorphisms defined by Shelukhin and finite if and only if the group of contactomorphisms is orderable. To prove this we show that intervals defined by the positivity relation are open with respect to the topology induced by the Hofer norm. For orderable Legendrian isotopy classes we show that the Chekanov-type metric defined by Rosen and Zhang is non-degenerate. In this case similar results hold for a…
We prove that the group of strict contactomorphisms of the standard tight contact structure on the three-sphere deformation retracts to its unitary subgroup U(2).
On the topology of loops of contactomorphisms and Legendrians in non-orderable manifolds
本文研究了非序闭切触流形的切触微分同胚环与勒让德子流形环空间的全局拓扑，通过正性度量进行过滤，并证明了其同伦群为正环子空间同伦群的子群。
Shelukhin's Hofer distance and a symplectic cohomology barcode for contactomorphisms
该研究构建了接触微分同胚相关的Floer上同调持久性模，证明其条形码距离上界为Shelukhin的Hofer距离，支撑于平移点长度，借此得到平移点存在性结果与满足单调性、连续性的谱不变量。
Contact manifolds are odd-dimensional smooth manifolds endowed with a maximally non-integrable field of hyperplanes. They are intimately related to symplectic manifolds, i.e. even-dimensional smooth manifolds endowed with a closed non-degenerate 2-form. Although in symplectic topology a famous bi-invariant metric, the Hofer metric, has been studied since more than 20 years ago, it is only recently that some somehow analogous bi-invariant metrics have been discovered on the group of diffeomorphisms that preserve a contact structure. In this expository article I will review some constructions of…
Strict contactomorphisms are scarce
本文证明对任意非可投影切触形式λ，其严格切触同胚集合是可数条实直线的无交并，每个连通分量对应一条实直线，从而表明严格切触同胚极其稀少。
A new metric on the contactomorphism group of orderable contact manifolds
本文在切触流形的切触同胚群上引入新伪度量，证明其非退化当且仅当流形强可序，且其度量拓扑与区间拓扑一致，从而回答了 Chernov 和 Nemirovski 的相关问题。
Let $S^*Q$ be the spherization of a closed connected manifold of dimension at least two. Consider a contactomorphism $φ$ that can be reached by a contact isotopy that is everywhere positively transverse to the contact structure. In other words, $φ$ is the time-1-map of a time-dependent Reeb flow. We show that the volume growth of $φ$ is bounded from below by the topological complexity of the loop space of $Q$. Denote by $ΩQ_0(q)$ the component of the based loop space that contains the constant loop. We show that if the fundamental group or the homology of $ΩQ_0(q)$ grows exponentially, then th…
Equivariant Floer cohomology for contactomorphisms of quotient spaces
本文研究接触流形商空间的可序性，通过等变接触Floer上同调理论发展非线性Maslov指数，并利用映射锥检测与判别点的交叉，以处理定义映射锥的非规范性。
A point q in a contact manifold is called a translated point for a contactomorphism ϕ, with respect to some fixed contact form, if ϕ(q) and q belong to the same Reeb orbit and the contact form is preserved at q. The problem of existence of translated points is related to the chord conjecture and to the problem of leafwise coisotropic intersections. In the case of a compactly supported contactomorphism of R^{2n+1} or R^{2n} x S^1 contact isotopic to the identity, existence of translated points follows immediately from Chekanov's theorem on critical points of quasi-functions and Bhupal's graph c…
Spectral selectors on lens spaces and applications to the geometry of the group of contactomorphisms
本文借助 Givental 非线性 Maslov 指标构造透镜空间接触微分同胚群上的谱选择子，并据此刻画 Reeb 流的测地性质及稳定无界谱伪范数。
In this article we address the existence of positive loops of contactomorphisms in overtwisted contact 3-folds. We present a construction of such positive loops in the contact fibered connected sum of certain contact 3-folds along transverse knots. In particular, we obtain positive loops of contactomorphisms in overtwisted contact structures.
We explain a connection between the algebraic and geometric properties of groups of contact transformations, open book decompositions, and flexible Legendrian embeddings. The main result is that, if a closed contact manifold $(V, ξ)$ has a supporting open book whose pages are flexible Weinstein manifolds, then the connected component $G$ of the identity in its automorphism group is a uniformly simple group: for every non-trivial element $g$, every other element is a product of at most $128(\dim V + 1)$ conjugates of $g^{\pm 1}$. In particular any conjugation invariant norm on this group is bou…
We prove, for a class of contact manifolds, that the universal cover of the group of contact diffeomorphisms carries a natural partial order. It leads to a new viewpoint on geometry and dynamics of contactomorphisms. It gives rise to invariants of contactomorphisms which generalize the classical notion of the rotation number. Our approach is based on tools of Symplectic Topology.
We give examples of contactomorphisms in every dimension that are smoothly isotopic to the identity but that are not contact isotopic to the identity. In fact, we prove the stronger statement that they are not even symplectically pseudo-isotopic to the identity. We also give examples of pairs of contactomorphisms which are smoothly conjugate to each other but not by contactomorphisms.
On contact mapping classes of prequantizations
本文构造了积分辛流形预量子化的例子，其具有无穷多个光滑平凡的接触映射类，并研究了辛同胚提升为严格接触同胚的问题。
We prove the existence of minimal symplectomorphisms and strictly ergodic contactomorphisms on manifolds which admit a locally free $\mathbb{S}^1$--action by symplectomorphisms and contactomorphisms, respectively. The proof adapts the conjugation method, introduced by Anosov and Katok, to the contact and symplectic setting.
Simplicity of the contactomorphism group of finite regularity
本文研究紧支撑有限Hölder正则性接触微分同胚群，证明其在除临界指数$(n+1,1/2)$外的所有正则性参数下均为完美群和单群。
Contactomorphic vertically convex domains
本文研究了垂直凸域的接触同构性质，通过分析平均曲率和特征长度，确定了不同域之间的分类与不变量。
A topology is introduced on spaces of Legendrian submanifolds and groups of contactomorphisms. The definition is motivated by the Alexandrov topology in Lorentz geometry.
We show that if the image of a Legendrian submanifold under a contact homeomorphism (i.e. a homeomorphism that is a $C^0$-limit of contactomorphisms) is smooth then it is Legendrian, assuming only positive local lower bounds on the conformal factors of the approximating contactomorphisms. More generally the analogous result holds for coisotropic submanifolds in the sense of arXiv:1306.6367. This is a contact version of the Humilière-Leclercq-Seyfaddini coisotropic rigidity theorem in $C^0$ symplectic geometry, and the proof adapts the author's recent re-proof of that result in arXiv:1912.13043…
We prove that on closed Riemannian manifolds with infinite abelian, but not cyclic, fundamental group, any isometry that is homotopic to the identity possesses infinitely many invariant geodesics. We conjecture that the result remains true if the fundamental group is infinite cyclic. We also formulate a generalization of the isometry-invariant geodesics problem, and a generalization of the celebrated Weinstein conjecture: on a closed contact manifold with a selected contact form, any strict contactomorphism that is contact-isotopic to the identity possesses an invariant Reeb orbit.
We study in this paper the remnants of the contact partial order on the orbits of the adjoint action of contactomorphism groups on their Lie algebras. Our main interest is a class of non-compact contact manifolds, called convex at infinity.
In this article, we prove that every contactomorphism of any standard contact lens space of dimension $2n-1$ that is contact-isotopic to identity has at least $2n$ translated points. This sharp lower bound refines a result of Granja-Karshon-Pabiniak-Sandon and answers a conjecture of Sandon positively.
Reductions: precontact versus presymplectic
本文将接触约化纳入 Marsden-Weinstein-Meyer 及常秩辛约化框架，通过辛覆盖把接触同胚群作用提升为哈密顿作用，并推广到预接触与预辛情形，揭示预接触流形与齐次预辛流形的一一对应。
We prove the non--triviality of the Reeb flow for the (2n+1)--dimensional standard contact spheres inside the fundamental group of their contactomorphism group, n greater than 3. The argument uses the existence of homotopically non--trivial 2--spheres in the space of contact structures of a 3--Sasakian manifold.
Contact 3-manifolds that admit a non-free toric action
本研究基于Lerman的工作，通过显式描述完成切触环面3-流形的切触同胚分类，并进一步分类了可作为球面上线形管道凹边界的3-流形的所有切触结构，相关结果受MNRSTW25工作启发。
We construct (infinitely many) examples in all dimensions of contactomorphisms of closed overtwisted contact manifolds that are smoothly isotopic but not contact-isotopic to the identity.
Interplay between Quantitative Aspects of Locally Conformally Symplectic Geometry and Contact Dynamics
本文研究了局部拟共形辛几何与接触动力学的相互作用，通过弹性概念刻画了LCS流形的性质，并建立了弹性极限值与Birkhoff平均的联系。
Exotic symplectomorphisms and contact circle actions
该研究利用Floer同调方法，建立了标准辛球上奇异辛同胚的不存在性与标准切触球面上自由切触圆周作用的拓扑约束的关联，还推广至Liouville域情形，应用于辛映射类群与切触同胚群基本群的研究。
We discuss a correspondence between certain contact pairs on the one hand, and certain locally conformally symplectic forms on the other. In particular, we characterize these structures through suspensions of contactomorphisms. If the contact pair is endowed with a normal metric, then the corresponding lcs form is locally conformally Kaehler, and, in fact, Vaisman. This leads to classification results for normal metric contact pairs. In complex dimension two we obtain a new proof of Belgun's classification of Vaisman manifolds under the additional assumption that the Kodaira dimension is non-n…
A theorem of Moser guarantees that every diffeomorphism of a closed manifold can be isotoped to a volume preserving one. We show that this statement cannot be extended into contact category: some connected components of contactomorphism groups of certain contact manifolds contain no volume-preserving diffeomorphisms. This phenomenon can be considered from different viewpoints: geometric (isometric action of the contact mapping class group on the moduli space of contact forms), topological (action in symplectic homology) and dynamical (diffusion). We define a numerical invariant - a kind of con…
A translated point of a contactomorphism $ϕ$ on a contact manifold with contact form $α$ is a point $p$ where $α$ is preserved under $ϕ$ and whose image under $ϕ$ lies in the same Reeb trajectory. They were introduced as a contact analogon for fixed points of Hamiltonian diffeomorphisms by Sheila Sandon and can be understood as a special case of leafwise fixed points. She established a contact version of the non-degenerate Arnol'd conjecture on spheres using a generating function approach. It turns out that Sandon's proof only works under the assumption that there exists a generating function …
We define Maslov--type indices associated to contact and symplectic transformation groups. There are two such families of indices. The first class of indices are maps from the homotopy groups of the contactomorphism or symplectomorphism group to a quotient of the integers. These are based on a generalization of the Maslov index. The second class of indices are maps from the homotopy groups of the space of contact structures or the space of cohomologous symplectic forms to the homotopy groups of a simple homogeneous space. We provide a detailed construction and describe some properties of these…
This is the preliminary manuscript of a book on symplectic field theory based on a lecture course for PhD students given in 2015-16. It covers the essentials of the analytical theory of punctured pseudoholomorphic curves, taking the opportunity to fill in gaps in the existing literature where necessary, and then gives detailed explanations of a few of the standard applications in contact topology such as distinguishing contact structures up to contactomorphism and proving symplectic non-fillability.
In this paper we study submanifolds of contact manifolds. The main submanifolds we are interested in are contact coisotropic submanifolds. Based on a correspondence between symplectic and contact coisotropic submanifolds, we can show contact coisotropic submanifolds admit a $C^0$-rigidity, similar to Humilière-Leclercq-Seyfaddini's coisotropic rigidity on symplectic manifolds. Moreover, based on Shelukhin's norm defined on the contactomorphism group, we define a Chekanov type pseudo-metric on the orbit space of a fixed submanifold of a contact manifold. Moreover, we can show a dichotomy of (no…
A contact-geometric variant of Smale's contraction
受Smale收缩启发，研究开放旋转对称Darboux球上垂直凸接触形式，证明三维可缩、五维同伦等价于紧支撑微分同胚群，并给出等变乘积分裂。
We classify Legendrian unknots in overtwisted contact structures on $S^3$. In particular, we show that up to contact isotopy for every pair $(n,\pm(n-1))$ with $n>0$ there are exactly two oriented non-loose Legendrian unknots in $S^3$ with Thurston-Bennequin invariant $n$ and rotation number $\pm(n-1)$. (Only one overtwisted contact structure on $S^3$ admits a non-loose unknot $K$ and the classical invariants have to be $\mathrm{tb}(K)=n$ and $\mathrm{rot}(K)=\pm(n-1)$ for $n>1$.) This can be used to prove two results attributed to Y.~Che\-kan\-ov: The first implies that the contact mapping cl…
Outer Contact Billiards
该研究提出外接触台球作为外辛台球的奇维对应物，证明其可生成接触同胚，实射影三维空间中二次曲面对应完全可积且无3周期轨道，仅一个二次表有4周期轨道。
In this paper we find connection between the Hofer's metric of the group of Hamiltonian diffeomorphisms of a closed symplectic manifold, with an integral symplectic form, and the geometry, defined in a paper by Eliashberg and Polterovich, of the quantomorphisms group of its prequantization manifold. This gives two main results: First, we calculate, partly, the geometry of the quantomorphisms groups of a prequantization manifolds of an integral symplectic manifold which admits certain Lagrangian foliation. Second, for every prequantization manifold we give a formula for the distance between a p…
We present some examples of locally conformal symplectic structures of the first kind on compact nilmanifolds which do not admit Vaisman metrics. One of these examples does not admit locally conformal Kähler metrics and all the structures come from left-invariant locally conformal symplectic structures on the corresponding nilpotent Lie groups. Under certain topological restrictions related with the compactness of the canonical foliation, we prove a structure theorem for locally conformal symplectic manifolds of the first kind. In the non compact case, we show that they are the product of a re…
扫码添加微信好友，提出您的宝贵建议 👇
💡 备注请填写：网站反馈
发表机构由 AI 从论文文本抽取，如发现错误，欢迎反馈修正建议。