Circle bundles over 4-manifolds

Minimal genus in circle bundles over 3-manifolds

An estimate for the genus function in circle bundles over irreducible 3-manifolds is proven. This estimate is in many cases an equality and it relates the minimal genus of the surfaces representing a given homology class with the self-intersection of the class and the Thurston norm of the underlying 3-manifold.

Homological stability for unlinked circles in a 3-manifold

We prove a homological stability theorem for unlinked circles in $3$-manifolds and give an application to certain groups of diffeomorphisms of 3-manifolds.

Tight, not semi--fillable contact circle bundles

Extending our earlier results, we prove that certain tight contact structures on circle bundles over surfaces are not symplectically semi--fillable, thus confirming a conjecture of Ko Honda.

On hyperbolic surface bundles over the circle as branched double covers of the $3$-sphere

The branched virtual fibering theorem by Sakuma states that every closed orientable $3$-manifold with a Heegaard surface of genus $g$ has a branched double cover which is a genus $g$ surface bundle over the circle. It is proved by Brooks that such a surface bundle can be chosen to be hyperbolic. We prove that the minimal entropy over all hyperbolic, genus $g$ surface bundles as branched double covers of the $3$-sphere behaves like 1/$g$. We also give an alternative construction of surface bundles over the circle in Sakuma's theorem when closed $3$-manifolds are branched double covers of the $3…

Elliptic open books on torus bundles over the circle

As an application of the construction of open books on plumbed 3-manifolds, we construct elliptic open books on torus bundles over the circle. In certain cases these open books are compatible with Stein fillable contact structures and have minimal genus.

The topology of symplectic circle bundles

We consider circle bundles over compact three-manifolds with symplectic total spaces. We show that the base of such a space must be irreducible or the product of the two-sphere with the circle. We then deduce that such a bundle admits a symplectic form if and only if it admits one that is invariant under the circle action in three special cases: namely if the base is Seifert fibered, has vanishing Thurston norm, or if the total space admits a Lefschetz fibration.

界定有理同调圆的环面丛的分类

Classification of torus bundles that bound rational homology circles

本文完全分类了界定具有圆的有理同调的4-流形的圆上环面丛，并探讨了链环整数手术及3-辫闭合双重分支覆盖与有理同调球的联系。

曲面丛和圆上丛的多剖分

Multisections of surface bundles and bundles over the circle

本文证明曲面丛和纤维已多剖分的圆上纤维丛在任意维度均承认多剖分，并给出显式构造与示例。

Isotopy Classification of Engel Structures on Circle Bundles

We call two Engel structures isotopic if they are homotopic through Engel structures by a homotopy that fixes the characteristic line field. In the present paper we define an isotopy invariant of Engel structures on oriented circle bundles over closed oriented three-manifolds and apply it to give an isotopy classification of Engel structures on circle bundles with characteristic line field tangent to the fibers.

某些单连通7维流形上的自由圆作用

Free circle actions on certain simply connected $7-$manifolds

研究确定哪些非负整数k,l和同调7球面Σ使kS²×S⁵#lS³×S⁴#Σ具有自由光滑圆作用

On conformally flat circle bundles over surfaces

We study surface groups $Γ$ in $SO(4,1)$, which is the group of Mobius tranformations of $S^3$, and also the group of isometries of $\mathbb{H}^4$. We consider such $Γ$ so that its limit set $Λ_Γ$ is a quasi-circle in $S^3$, and so that the quotient $(S^3 - Λ_Γ) / Γ$ is a circle bundle over a surface. This circle bundle is said to be conformally flat, and our main goal is to discover how twisted such bundle may be by establishing a bound on its Euler number. By combinatorial approaches, we have two soft bounds in this direction on certain types of nice structures. In this article we also const…

关于具有双曲基本群的非球面流形上圆丛的Hopf问题

On a problem of Hopf for circle bundles over aspherical manifolds with hyperbolic fundamental groups

本文完全刻画了具有双曲基本群的闭可定向非球面流形上圆丛的绝对度大于一的自映射存在性，证明其等价于丛虚拟平凡，并由此验证了Hopf问题的强版本，同时构造了关于映射度单调的新数值不变量。

Mapping class groups of circle bundles over a surface

In this paper, we study the algebraic structure of mapping class group $Mod(X)$ of 3-manifolds $X$ that fiber as a circle bundle over a surface $S^1\rightarrow X\rightarrow S_g$. There is an exact sequence $1\rightarrow H^1(S_g)\rightarrow Mod(X)\rightarrow Mod(S_g)\rightarrow1$. We relate this to the Birman exact sequence and determine when this sequence splits.

Counting triangles formula for the first Chern class of a circle bundle

We consider the problem of the combinatorial computation of the first Chern class of a circle bundle. N.Mnev found such a formula in terms of canonical shellings. It represents certain invariant of a triangulation computed by analyzing cyclic word in 3-character alphabet associated to the bundle. This curvature is a kind of discretization of Konstevich's curvature differential 2-form. We find a new expression of Mnev's curvature by counting triangles in a cyclic word. Our formula is different from that of Mnev. In particular, it is cyclically invariant by its very form. We present also some sa…

圆丛中的纽结由其补集决定

Knots in circle bundles are determined by their complements

本文证明了亏格 $g \geq 2$ 曲面上的可定向圆丛中的纽结由其补集决定，解决了有向纽结补集猜想的一个情形，并应用于单位切丛和射影切丛中的典范纽结，给出了其补集同胚的充分必要条件。

$(n-1)$-连通$(2n+1)$-流形上的自由圆周作用

Free circle actions on $(n-1)$-connected $(2n+1)$-manifolds

该研究在n≡5,7模8的条件下，对容许自由圆周作用的同调无挠(n-1)-连通(2n+1)-流形完成了几乎微分同胚意义下的分类。

On the contact mapping class group of Legendrian circle bundles

In this paper, we determine the group of contact transformations modulo contact isotopies for Legendrian circle bundles over closed surfaces of nonpositive Euler characteristic. These results extend and correct those presented by the first author in a former work. The main ingredient we use is connectedness of certain spaces of embeddings of surfaces into contact 3-manifolds. In the third section, this connectedness question is studied in more details with a number of (hopefully instructive) examples.

On three-manifolds dominated by circle bundles

We determine which three-manifolds are dominated by products. The result is that a closed, oriented, connected three-manifold is dominated by a product if and only if it is finitely covered either by a product or by a connected sum of copies of the product of the two-sphere and the circle. This characterization can also be formulated in terms of Thurston geometries, or in terms of purely algebraic properties of the fundamental group. We also determine which three-manifolds are dominated by non-trivial circle bundles, and which three-manifold groups are presentable by products.

Minimal Balanced Triangulations of Sphere Bundles over the Circle

We determine the minimum number of vertices needed to provide balanced triangulations of $\mathbb S^{d-2}$-bundles over $\mathbb S^1$. If $d$ is odd and the bundle is orientable, or $d$ is even and the bundle is non-orientable, the minimum number of vertices is $3d$; otherwise, it is $3d+2$. Similar results apply to all balanced simplicial complexes that triangulate homology manifolds with $β_1\neq 0$ and $β_2=0$, where $β_i$'s are the Betti numbers, computed with coefficients in $\mathbb Q$.

环动作与光滑流形上的悬垂操作

Circle actions and Suspension operations on Smooth manifolds

研究光滑流形上的环动作与悬垂操作，通过环状手术构造并分类具有自由S¹动作的流形。

圆上纤维丛的相对三剖分

Relative trisections of fiber bundles over the circle

本文研究定向四维圆上纤维丛的三剖分构造，提出从纤维的缝合 Heegaard 分裂出发，通过算法显式构造相对三剖分图，并利用图的粘合恢复闭纤维丛和旋流形的三剖分，同时给出四维开书分解的三剖分。

Complexity of torus bundles over the circle with monodromy (2 1, 1 1)

We find the exact values of complexity for an infinite series of 3-manifolds. Namely, by calculating hyperbolic volumes, we show that c(N_n)=2n, where $c$ is the complexity of a 3-manifold and N_n is the total space of the punctured torus bundle over S^1 with monodromy 2&1 1&1 ^n$. We also apply a recent result of Matveev and Pervova to show that c(M_n) \ge 2Cn with C\approx 0.598, where a compact manifold M_n is the total space of the torus bundle over S^1 with the same monodromy as N_n, and discuss an approach to the conjecture c(M_n)=2n+5 based on the equality c(N_n)=2n.

圆丛的拟截面与欧拉类

Quasisections of circle bundles and Euler class

本文研究定向闭曲面上圆丛的拟截面，推导出用拟截面奇点权之和表示欧拉数的局部公式，并证明其唯一性，建立了与 Kazarian 关于 Morse 分岔公式的联系。

Profinite rigidity and surface bundles over the circle

If $M$ is a compact 3-manifold whose first betti number is 1, and $N$ is a compact 3-manifold such that $π_1N$ and $π_1M$ have the same finite quotients, then $M$ fibres over the circle if and only if $N$ does. We prove that groups of the form $F_2\rtimes\mathbb{Z}$ are distinguished from one another by their profinite completions. Thus, regardless of betti number, if $M$ and $N$ are punctured torus bundles over the circle and $M$ is not homeomorphic to $N$, then there is a finite group $G$ such that one of $π_1M$ and $π_1N$ maps onto $G$ and the other does not.

Constructions of round fold maps on circle bundles

{\it Fold maps} are fundamental tools in generalizing the theory of Morse functions and its application to studies of geometric properties of manifolds. One of the fundamental and important problems in the theory of fold maps is to construct explicit fold maps, which are often difficult. In this paper, we construct new examples of {\it round fold maps}, which are defined as {\it stable fold maps} with singular value sets of concentric spheres introduced by the author on manifolds having the structures of circle bundles. The class of round fold maps includes some {\it special generic} maps on h…

Invariants of Legendrian knots in circle bundles

Let E be a circle bundle over a Riemann surface that supports a contact structure transverse to the fibers. This paper presents a combinatorial definition of a differential graded algebra (DGA) that is an invariant of Legendrian knots in E. The invariant generalizes Chekanov's combinatorial DGA invariant of Legendrian knots in the standard contact 3-space using ideas from Eliashberg, Givental, and Hofer's contact homology. The main difficulty lies in dealing with what are ostensibly 1-parameter families of generators for the DGA; these are solved using ``Morse-Bott'' techniques. As an applicat…

关于辛流形上圆丛的Stein可填充性的注记

A note on Stein fillability of circle bundles over symplectic manifolds

本文证明了维数 $2n \geq 4$ 的闭积分辛流形上，当整数 $k>\int_Σω^{n}$ 时，$(Σ, kω)$ 上的Boothby-Wang丛不带有Stein可填充切触结构，从而否定地回答了Eliashberg的问题，并证明了某些孤立奇点的不可平滑性。

Non-positively curved graph manifolds are virtually fibered over the circle

In this note we prove that any closed graph manifold admitting a metric of non-positive sectional curvature (NPC-metric) has a finite cover, which is fibered over the circle. An explicit criterion to have a finite cover, which is fibered over the circle, is presented for the graph manifolds of certain class.

Circle action and some vanishing results on manifolds

Kawakubo and Uchida showed that, if a closed oriented $4k$-dimensional manifold $M$ admits a semi-free circle action such that the dimension of the fixed point set is less than $2k$, then the signature of $M$ vanishes. In this note, by using $G$-signature theorem and the rigidity of the signature operator, we generalize this result to more general circle actions. Combining the same idea with the remarkable Witten-Taubes-Bott rigidity theorem, we explore more vanishing results on spin manifolds admitting such circle actions. Our results are closely related to some earlier results of Conner-Floy…

Hirzebruch genera of manifolds equipped with a Hamiltonian circle action

In the paper we describe obstructions for the existence of symplectic and Hamiltonian symplectic circle actions on closed compact manifolds in terms of Hirzebruch genera and relations between differential and homotopic invariants of such manifolds.

Non-fillable invariant contact structures on principal circle bundles and left-handed twists

We define symplectic fractional twists, which generalize Dehn twists, and use these in open books to investigate contact structures. The resulting contact structures are invariant under a circle action, and share several similarities with the invariant contact structures that were studied by Lutz and Giroux. We show that left-handed fractional twists often give rise to non-fillable contact manifolds. These manifolds are in fact "algebraically overtwisted", yet they do not seem to contain bLobs, nor are they directly related to negative stabilizations. We also show that the Weinstein conjecture…

Profinite刚性及圆周上的双曲四穿孔球丛

Profinite rigidity and hyperbolic four-punctured sphere bundles over the circle

本文证明了圆周上的双曲四穿孔球丛可由其基本群的有限商群在所有3-流形群中被唯一区分，并通过改进Liu的结果证明了纤维拓扑类型可由profinite完备性检测。

环作用于定向四维流形

Circle actions on oriented 4-manifolds

本文研究环作用于定向四维流形的性质，推导Atiyah-Hirzebruch公式，并通过固定点集的数据构建图，证明在孤立固定点情况下，满足该公式的抽象图对应于四维定向S¹-流形。

Some remarks on circle action on manifolds

This paper contains several results concerning circle action on almost-complex and smooth manifolds. More precisely, we show that, for an almost-complex manifold $M^{2mn}$(resp. a smooth manifold $N^{4mn}$), if there exists a partition $λ=(λ_{1},...,λ_{u})$ of weight $m$ such that the Chern number $(c_{λ_{1}}... c_{λ_{u}})^{n}[M]$ (resp. Pontrjagin number $(p_{λ_{1}}... p_{λ_{u}})^{n}[N]$) is nonzero, then \emph{any} circle action on $M^{2mn}$ (resp. $N^{4mn}$) has at least $n+1$ fixed points. When an even-dimensional smooth manifold $N^{2n}$ admits a semi-free action with isolated fixed point…

Subsurface distances for hyperbolic 3-manifolds fibering over the circle

For a hyperbolic fibered 3-manifold M, we prove results that uniformly relate the structure of surface projections as one varies the fibrations of M. This extends our previous work from the fully-punctured to the general case.

Discriminant circle bundles over local models of Strebel graphs and Boutroux curves

We study special circle bundles over two elementary moduli spaces of meromorphic quadratic differentials with real periods denoted by $\mathcal Q_0^{\mathbb R}(-7)$ and $\mathcal Q^{\mathbb R}_0([-3]^2)$. The space $\mathcal Q_0^{\mathbb R}(-7)$ is the moduli space of meromorphic quadratic differentials on the Riemann sphere with one pole of order 7 with real periods; it appears naturally in the study of a neighbourhood of the Witten's cycle $W_1$ in the combinatorial model based on Jenkins-Strebel quadratic differentials of $\mathcal M_{g,n}$. The space $\mathcal Q^{\mathbb R}_0([-3]^2)$ is t…

Symplectic 4-manifolds with fixed point free circle actions

We show that recent results of Friedl-Vidussi and Chen imply that a symplectic manifold admits a fixed point free circle action if and only if it admits a symplectic circle action and we give a complete description of the symplectic cone in this case. This then completes the characterisation of symplectic 4-manifolds that admit non-trivial circle actions.

The rank of the fundamental group of certain hyperbolic 3-manifolds fibering over the circle

We determine the rank of the fundamental group of those hyperbolic 3-manifolds fibering over the circle whose monodromy is a sufficiently high power of a pseudo-Anosov map. Moreover, we show that any two generating sets with minimal cardinality are Nielsen equivalent.

Minimal genus in 4-manifolds with a free circle action

Let N be a closed irreducible 3-manifold and assume N is not a graph manifold. We improve for all but finitely many S^1-bundles M over N the adjunction inequality for the minimal complexity of embedded surfaces. This allows us to completely determine the minimal complexity of embedded surfaces in all but finitely many S^1-bundles over a large class of 3-manifolds.

Dynamics on geometrically finite hyperbolic manifolds with applications to Apollonian circle packings and beyond

We present recent results on counting and distribution of circles in a given circle packing invariant under a geometrically finite Kleinian group and discuss how the dynamics of flows on geometrically finite hyperbolic $3$ manifolds are related. Our results apply to Apollonian circle packings, Sierpinski curves, Schottky dances, etc.

Complex contact manifolds and circle actions

We prove rigidity and vanishing theorems for several holomorphic Euler characteristics on complex contact manifolds admitting holomorphic circle actions preserving the contact structure. Such vanishings are reminiscent of those of LeBrun and Salamon on Fano contact manifolds but under a symmetry assumption instead of a curvature condition.

Circle actions on simply connected 5--manifolds

The aim of this paper is to study compact 5--manifolds which admit fixed point free circle actions. The first result implies that the torsion in the second homology and the second Stiefel--Whitney class have to satisfy strong restrictions. We then show that for simply connected 5--manifolds these restrictions are necessary and sufficient.

Seiberg-Witten invariants of 4-manifolds with free circle actions

The main results of this paper describes a formula for the Seiberg-Witten invariant of a 4-manifold which admits a nontrivial free S^1-action. We use this theorem to produce a nonsymplectic 4-manifold with a free circle action whose orbit space fibers over S^1. We also describe a 3-manifold which is not the orbit space of any symplectic 4-manifold with a free circle action. A corollary of the main theorem is a formula for the 3-dimensional Seiberg-Witten invariants of the total space of a circle bundle over a surface.

Real places and torus bundles

If M is a hyperbolic once-punctured torus bundle over the circle, then the trace field of M has no real places.

用特定 Morse-Bott 函数刻画表示为 Lens 空间、$S^2 \ imes S^1$ 和环面在圆上的丛的连通和的 $3$ 维流形

Characterizing $3$-dimensional manifolds represented as connected sums of Lens spaces, $S^2 \times S^1$, and torus bundles over the circle by certain Morse-Bott functions

本文用特定 Morse-Bott 函数刻画表示为 Lens 空间、$S^2 \ imes S^1$ 和环面在圆上的丛的连通和的 $3$ 维流形，强化并明确了 Saeki 2006 年的相关结果。

Laminar groups and 3-manifolds

Thurston showed that the fundamental group of a close atoroidal 3-manifold admitting a co-oriented taut foliation acts faithfully on the circle by orientation-preserving homeomorphisms. This action on the circle is called a universal circle action due to its rich information. In this article, we first review Thurston's theory of universal circles and follow-up work of other authors. We note that the universal circle action of a 3-manifold group always admits an invariant lamination. A group acting on the circle with an invariant lamination is called a laminar group. In the second half of the p…

Rational Growth and Almost Convexity of Higher-Dimensional Torus Bundles

Given a matrix $A\in SL(N,\Z)$, form the semidirect product $G=\Z^N\rtimes_A \Z$ where the $\Z$ factor acts on $\Z^N$ by $A$. Such a $G$ arises naturally as the fundamental group of an $N$-dimensional torus bundle which fibers over the circle. In this paper we prove that if $A$ has distinct eigenvalues not lying on the unit circle, then there exists a finite index subgroup $H\leq G$ possessing rational growth series for some generating set. In contrast, we show that if $A$ has at least one eigenvalue not lying on the unit circle, then $G$ is not almost convex for any generating set.

Three-manifolds, Foliations and Circles, I

This paper investigates certain foliations of three-manifolds that are hybrids of fibrations over the circle with foliated circle bundles over surfaces: a 3-manifold slithers around the circle when its universal cover fibers over the circle so that deck transformations are bundle automorphisms. Examples include hyperbolic 3-manifolds of every possible homological type. We show that all such foliations admit transverse pseudo-Anosov flows, and that in the universal cover of the hyperbolic cases, the leaves limit to sphere-filling Peano curves. The skew R-covered Anosov foliations of Sergio Fenl…

瞬子同调中的幂零性，以及曲面与圆周乘积的带框架瞬子同调

Nilpotency in instanton homology, and the framed instanton homology of a surface times a circle

本文在 Muñoz 工作的基础上计算了瞬子 Floer 同调中自同态 $u^2-64$ 的幂零次数，并进一步计算了非平凡丛情形下曲面与圆周乘积的带框架瞬子同调，揭示了其与 $u^2-64$ 核的紧密联系。

An example of a closed 5-manifold of nonpositive curvature that fibers over a circle

We exhibit a closed aspherical 5-manifold of nonpositive curvature that fibers over a circle whose fundamental group is hyperbolic relative to abelian subgroups such that the fiber is a closed aspherical 4-manifold whose fundamental group is not hyperbolic relative to abelian subgroups.

Symplectic 4-manifolds with a free circle action

The content of this unpublished paper is subsumed in successive work of the authors, in particular arXiv:1102.0820, arXiv:1102.0821 and arXiv:1205.2434.

双曲6流形上的完美圆值Morse函数

Perfect circle-valued Morse functions on hyperbolic 6-manifolds

本文首次构造了具有完美圆值Morse函数的双曲6流形，并由此得到双曲群中一个类型为F2而非F3的子群新例子。

Apollonian circle packings and closed horospheres on hyperbolic 3-manifolds

We obtain an asymptotic formula for the number of circles of curvature at most T in any given bounded Apollonian circle packing. For an integral packing, we obtain the upper bounds for the number of circles with prime curvature as well as of pairs of circles with prime curvatures, which are sharp up constant multiples. The main ingredient of our proof is the effective equidistribution of expanding horospheres on geometrically finite hyperbolic 3-manifolds under the assumption that the critical exponent of its fundamental group exceeds one.

Dihedral manifold approximate fibrations over the circle

Consider the cyclic group C_2 of order two acting by complex-conjugation on the unit circle S^1. The main result is that a finitely dominated manifold W of dimension > 4 admits a cocompact, free, discontinuous action by the infinite dihedral group D_\infty if and only if W is the infinite cyclic cover of a free C_2-manifold M such that M admits a C_2-equivariant manifold approximate fibration to S^1. The novelty in this setting is the existence of codimension-one, invariant submanifolds of M and W. Along the way, we develop an equivariant sucking principle for certain orthogonal actions of fin…