Topological spines of 4-manifolds

Branched Spines and Contact Structures on 3-manifolds

We introduce and analyze the characteristic foliation induced by a contact structure on a branched surface, in particular a branched standard spine of a 3-manifold. We extend to (fairly general) singular foliations of branched surfaces the local existence and uniqueness results which hold for genuine surfaces. Moreover we show that global uniqueness holds when restricting to tight structures. We establish branched versions of the elimination lemma. We prove a smooth version of the Gillman-Rolfsen PL-embedding theorem, deducing that branched spines can be used to construct contact structures in…

3-流形脊上的弧图

Arc diagrams on 3-manifold spines

本文研究链环到3-流形三价脊的投影，建立Reidemeister型组合移动定理，并证明无交叉投影的存在性及其等价移动，还将其联系到Turaev影子世界。

Four manifolds with no smooth spines

Let $W$ be a compact smooth $4$-manifold that deformation retract to a PL embedded closed surface. One can arrange the embedding to have at most one non-locally-flat point, and near the point the topology of the embedding is encoded in the singularity knot $K$. If $K$ is slice, then $W$ has a smooth spine, i.e., deformation retracts onto a smoothly embedded surface. Using the obstructions from the Heegaard Floer homology and the high-dimensional surgery theory, we show that $W$ has no smooth spines if $K$ is a knot with nonzero Arf invariant, a nontrivial L-space knot, the connected sum of non…

Traversing three-manifold triangulations and spines

A celebrated result concerning triangulations of a given closed 3-manifold is that any two triangulations with the same number of vertices are connected by a sequence of so-called 2-3 and 3-2 moves. A similar result is known for ideal triangulations of topologically finite non-compact 3-manifolds. These results build on classical work that goes back to Alexander, Newman, Moise, and Pachner. The key special case of 1-vertex triangulations of closed 3-manifolds was independently proven by Matveev and Piergallini. The general result for closed 3-manifolds can be found in work of Benedetti and Pet…

A calculus for branched spine of 3-manifolds

We establish a calculus for branched spines of 3-manifolds by means of branched Matveev-Piergallini moves and branched bubble-moves. We briefly indicate some of its possible applications in the study and definition of State-Sum Quantum Invariants.

Approximation rigidity and $h$-principle for Bing spines

We show that all PL manifolds of dimension $\geq 3$ have spines similar to Bing's house with two rooms. Beyond this we explore approximation rigidity and an $h$-principle.

正流-脊与切触3-流形

Positive flow-spines and contact 3-manifolds

本文引入流-脊的正性概念，证明闭连通定向3-流形的正流-脊在相差同痕意义下唯一支撑切触结构，并指出正性条件对唯一支撑切触结构的存在性至关重要。

Towards Lower Bounds for Complexity of 3-Manifolds: a Program

For a 3-dimensional manifold $M^3$, its complexity $c(M^3)$, introduced by S.Matveev, is the minimal number of vertices of an almost simple spine of $M^3$; in many cases it is equal to the minimal number of tetrahedra in a singular triangulation of $M^3$. An approach to estimating $c(M^3)$ from below for total spaces of torus bundles over $S^1$, based on the study of theta-curves in the fibers, is developed, and pseudominimal special spines for these manifolds are constructed, which we conjecture to be their minimal spines. We also show how to apply some of these ideas to other 3-manifolds.

关于分支配边的 Matveev-Piergallini 移动

On Matveev-Piergallini moves for branched spines

本文证明了分支配边上的16种 Matveev-Piergallini 移动可由基本 MP 移动和纯滑动移动导出，从而简化了闭 $3$-流形和梳状 $3$-流形的组合描述，并扩展至带框和旋量 $3$-流形，有助于理解量子不变量。

Geometrical spines of lens manifolds

Geometrical spines are defined for 3-manifolds with natural metrics, in particular, for lens manifolds. We show that any spine of L(p,q) close enough to its geometrical spine (i.e., to the cut locus with respect to the standard metric) contains at least E(p,q)-3 vertices, which is exactly the conjectured value for Matveev's complexity of L(p,q); here E(p,q) stands for the sum of the elements of the continued fraction expansion of p/q. As a byproduct, we find the minimal (over all triangulations) rotation distance (the term coined by Sleator, Tarjan, and Thurston) between a triangulation of a r…

3-manifolds lying in trisected 4-manifolds

The spine of a trisected 4-manifold is a singular 3-dimensional set from which the trisection itself can be reconstructed. 3-manifolds embedded in the trisected 4--manifold can often be isotoped to lie almost or entirely in the spine of the trisection. We define this notion and show that in fact every 3-manifold can be embedded to lie almost in the spine of a minimal genus trisection of some connect sum of $S^2 \tilde \times S^2$s. This mirrors the known fact that every 3-manifold can be smoothly embedded in a connect sum of $S^2 \times S^2$s. Our methods additionally give an upper bound for h…

填充三维流形中的链环与脊

Filling links and spines in 3-manifolds

本文定义三维流形中的填充与 k-填充链环，在三维环面中构造 k-填充链环，并借助推广的 Stallings 定理证明相关结论，附录还确立秩为 2 的闭可定向三维流形中存在填充双曲链环。

具有罕见Whitehead图的3-流形脊循环表示

3-manifold spine cyclic presentations with seldom seen Whitehead graphs

研究一类循环表示作为闭3-流形脊的条件，展示其约化Whitehead图与Fractional Fibonacci表示同型，并用正循环表示构造透镜空间，提供与类型 $\mathfrak{Z}$ 同型的新示例。

正流形脊与切触3-流形，II

Positive flow-spines and contact 3-manifolds, II

本文证明从正流形脊合痕类到切触结构合痕类的自然映射是满射，并由此推出任意流形脊可通过正则移动变形为正流形脊。

Cusped hyperbolic 3-manifolds: canonically CAT(0) with CAT(0) spines

We prove that every finite-volume hyperbolic 3-manifold M with p > 0 cusps admits a canonical, complete, piecewise Euclidean CAT(0) metric, with a canonical projection to a CAT(0) spine K. Moreover, (a) the universal cover of M endowed with the CAT(0) metric is a union of Euclidean half-spaces, glued together by identifying Euclidean polygons in their bounding planes by pairwise isometry (b)each cusp of M in the CAT(0) metric is a non-singular metric product of a (Euclidean) cusp torus and a half-line (c) all metric singularities are concentrated on the 1-skeleton of K, with cone angles a mult…

Convexity of Morse Stratifications and Gradient Spines of 3-Manifolds

We notice that a generic nonsingular gradient field $v = \nabla f$ on a compact 3-fold $X$ with boundary canonically generates a simple spine $K(f, v)$ of $X$. We study the transformations of $K(f, v)$ that are induced by deformations of the data $(f, v)$. We link the Matveev complexity $c(X)$ of $X$ with counting the \emph{double-tangent} trajectories of the $v$-flow, i.e. the trajectories that are tangent to the boundary $\d X$ at a pair of distinct points. Let $gc(X)$ be the minimum number of such trajectories, minimum being taken over all nonsingular $v$'s. We call $gc(X)$ the \emph{gradie…

Nonpositive Towers in Bing's Neighbourhood

Every 2-dimensional spine of an aspherical 3-manifold has the nonpositive towers property, but every collapsed 2-dimensional spine of a 3-ball containing a 2-cell has an immersed sphere.

Spine removal surgery and the geography of symplectic fillings

We prove that for any contact 3-manifold supported by a spinal open book decomposition with planar pages, there is a universal bound on the Euler characteristic and signature of its minimal symplectic fillings. The proof is an application of the spine removal surgery operation recently introduced in joint work of the authors with Van Horn-Morris.

3-manifolds and 4-dimensional surgery

Let $X$ be a connected compact 3-manifold with non-empty boundary. Consider the boundary $M$ of $X\times D^2$. $M$ is a 4-dimensional closed manifold and has the same fundamental group as $X$. Various examples of $X$ are known for which a certain assembly map $A:H_4(X;L)\to L_4(π_1(X))$ is injective. For such an $X$ and any CW-spine $B$ of $X$, there is a $UV^1$-map $p:M\to B$. For any $ε>0$, if the surgery obstruction for a TOP normal map $(f,b):N\to M$ vanishes, we can perform surgery on $f$ to change it into a $p^{-1}(ε)$-controlled homotopy equivalence.

Links, two-handles, and four-manifolds

We show that only finitely many links in a closed 3-manifold share the same complement, up to twists along discs and annuli. Using the same techniques, we prove that by adding 2-handles on the same link we get only finitely many smooth cobordisms between two given closed 3-manifolds. As a consequence, there are finitely many smooth closed 4-manifolds constructed from some Kirby diagram with bounded number of crossings, discs, and strands, or from some Turaev special shadow with bounded number of vertices. (These are the 4-dimensional analogues of Heegaard diagrams and special spines for 3-mani…

Embeddings of homology equivalent manifolds with boundary

We prove a theorem on equivariant maps implying the following two corollaries: (1) Let N and M be compact orientable n-manifolds with boundaries such that M\subset N, the inclusion M\to N induces an isomorphism in integral cohomology, both M and N have (n-d-1)-dimensional spines and m > max {n+2, (3n+1-d)/2} . Then the restriction-induced map E^m(N)\to E^m(M) is bijective. Here E^m(X) is the set of embeddings X\to R^m up to isotopy (in the PL or smooth category). (2) For a 3-manifold N with boundary whose integral homology groups are trivial and such that N\not\cong D^3 (or for its special 2-s…

Certifying a compact topological 4-manifold

We prove that compact topological 4-manifolds can be effectively presented by a finite amount of data.

Complexity of 3-orbifolds

We extend Matveev's theory of complexity for 3-manifolds, based on simple spines, to (closed, orientable, locally orientable) 3-orbifolds. We prove naturality and finiteness for irreducible 3-orbifolds, and, with certain restrictions and subtleties, additivity under orbifold connected sum. We also develop the theory of handle decompositions for 3-orbifolds and the corresponding theory of normal 2-suborbifolds.

Topological manifolds are locally-flat Euclidean neighbourhood retracts

We show that every topological n-manifold M admits a locally flat closed embedding $ι\colon M \hookrightarrow \mathbb{R}^{2n+1}$ and is a retract of some neighbourhood $U \subseteq \mathbb{R}^{2n+1}$

Topological rigidity of higher graph manifolds

In this short note we prove the Borel conjecture for a family of aspherical manifolds that includes higher graph manifolds.

Topological Symmetry Groups of Graphs in 3-Manifolds

We prove that for every closed, connected, orientable, irreducible 3-manifold, there exists an alternating group A_n which is not the topological symmetry group of any graph embedded in the manifold. We also show that for every finite group G, there is an embedding Γ of some graph in a hyperbolic rational homology 3-sphere such that the topological symmetry group of Γ is isomorphic to G.

On the geometric and topological rigidity of hyperbolic 3-manifolds

A homotopy equivalence between a hyperbolic 3-manifold and a closed irreducible 3-manifold is homotopic to a homeomorphsim provided the hyperbolic manifold satisfies a purely geometric condition. There are no known examples of hyperbolic 3-manifolds which do not satisfy this condition.

Topological structure of functions with isolated critical points on a 3-manifold

To each isolated critical point of a smooth function on a 3-manifold we put in correspondence a tree (graph without cycles). We will prove that functions are topologically equivalent in the neighborhoods of critical points if and only if the corresponding trees are isomorphic. A complete topological invariant of functions with isolated critical points, on a closed 3-manifold, will be constructed.

Homology Lens Spaces in Topological 4-Manifolds

For a closed 4-manifold X and closed 3-manifold M we investigate the smallest integer n (perhaps infinity) such that M embeds in the connected sum of n copies of X. It is proven that any lens space (or homology lens space) embeds topologically locally flatly in a connected sum of 8 copies of the complex projective plane.

Topological classification of Morse-Smale diffeomorphisms without heteroclinic curves on 3-manifolds

We show that, up to topological conjugation, the equivalence class of a Morse-Smale diffeomorphism without heteroclinic curves on 3-manifold is completely defined by an em- bedding of two-dimensional stable and unstable heteroclinic laminations to a characteristic space.

Topologically flat embedded 2-spheres in specific simply connected 4-manifolds

In this note we study whether specific elements in the second homology of specific simply connected closed $4$-manifolds can be represented by smooth or topologically flat embedded spheres.

Topologically slice knots that are not smoothly slice in any definite 4-manifold

We prove that there exist infinitely many topologically slice knots which cannot bound a smooth null-homologous disk in any definite 4-manifold. Furthermore, we show that we can take such knots so that they are linearly independent in the the knot concordance group.

Countable approximation of topological $G$-manifolds: compact Lie groups $G$

Let $G$ be a compact Lie group. (Compact) topological $G$-manifolds have the $G$-homotopy type of (finite-dimensional) countable $G$-CW complexes (2.5). This partly generalizes Elfving's theorem for locally linear $G$-manifolds [Elf96], wherein the Lie group $G$ is linear (such as compact).

Topological rigidity for non-aspherical manifolds

The Borel Conjecture predicts that closed aspherical manifolds are topological rigid. We want to investigate when a non-aspherical oriented connected closed manifold M is topological rigid in the following sense. If f: N --> M is an orientation preserving homotopy equivalence with a closed oriented manifold as target, then there is an orientation preserving homeomorphism h: N --> M such that h and f induce up to conjugation the same maps on the fundamental groups. We call such manifolds Borel manifolds. We give partial answers to this questions for S^k x S^d, for sphere bundles over aspherical…

Hyperbolic manifolds containing high topological index surfaces

If a graph is in bridge position in a 3-manifold so that the graph complement is irreducible and boundary irreducible, we generalize a result of Bachman and Schleimer to prove that the complexity of a surface properly embedded in the complement of the graph bounds the graph distance of the bridge surface. We use this result to construct, for any natural number $n$, a hyperbolic manifold containing a surface of topological index $n$.

4-流形中拓扑曲面的灯泡光滑化

Light bulb smoothing for topological surfaces in 4-manifolds

本文提出4-流形中拓扑嵌入曲面的新光滑化技术，实现拓扑到光滑的同痕，并应用于证明维度4中某些圆盘和球面的“拓扑=光滑”结果，同时获得Dax不变量的拓扑版本。

带边界几何对偶的4流形中曲面的光滑拓扑同痕

Smoothing topological isotopy of surfaces in 4-manifolds with a boundary geometric dual

本文证明在带边界几何对偶的光滑可定向4流形中，整洁曲面的拓扑同痕蕴含光滑同痕，从而建立光滑与拓扑同痕类间的双射。

ER同调流形上的拓扑中位代数结构 I：局部立方化

Topological median algebra structures on ER homology manifolds I: local cubulation

本文研究了ER同调流形上的拓扑中位代数结构，证明其具有局部CAT(0)立方化结构，并探讨了其度量化条件及构造非局部立方化结构的方法。

Topological Index Theory for Surfaces in 3-Manifolds

The disk complex of a surface in a 3-manifold is used to define its {\it topological index}. Surfaces with well-defined topological index are shown to generalize well-known classes, such as incompressible, strongly irreducible, and critical surfaces. The main result is that one may always isotope a surface $H$ with topological index $n$ to meet an incompressible surface $F$ so that the sum of the indices of the components of $H \setminus N(F)$ is at most $n$. This theorem and its corollaries generalize many known results about surfaces in 3-manifolds, and often provides more efficient proofs. …

Complexity of PL-manifolds

We extend Matveev's complexity of 3-manifolds to PL compact manifolds of arbitrary dimension, and we study its properties. The complexity of a manifold is the minimum number of vertices in a simple spine. We study how this quantity changes under the most common topological operations (handle additions, finite coverings, drilling and surgery of spheres, products, connected sums) and its relations with some geometric invariants (Gromov norm, spherical volume, volume entropy, systolic constant). Complexity distinguishes some homotopically equivalent manifolds and is positive on all closed aspheri…

Cohomogeneity one topological manifolds revisited

We prove a structure theorem for closed topological manifolds of cohomogeneity one; this result corrects an oversight in the literature. We complete the equivariant classification of closed, simply connected cohomogeneity one topological manifolds in dimensions $5$, $6$, and $7$ and obtain topological characterizations of these spaces. In these dimensions, these manifolds are homeomorphic to smooth manifolds.

Piecewise linear structures on topological manifolds

This is a survey paper where we expose the Kirby--Siebenmann results on classification of PL structures on topological manifolds and, in particular, the homotopy equivalence TOP/PL=K(Z/2.3) and the Hauptvermutung for manifolds.

Minimal volume invariants, topological sphere theorems and biorthogonal curvature on 4-manifolds

The goal of this article is to establish estimates involving the Yamabe minimal volume, mixed minimal volume and some topological invariants on compact 4-manifolds. In addition, we provide topological sphere theorems for compact submanifolds of spheres and Euclidean spaces, provided that the full norm of the second fundamental form is suitably bounded.

Countable approximation of topological $G$-manifolds, II: linear Lie groups $G$

Let $G$ be a matrix group. Topological $G$-manifolds with Palais-proper action have the $G$-homotopy type of countable $G$-CW complexes (3.2). This generalizes E Elfving's dissertation theorem for locally linear $G$-manifolds (1996). Also we improve the Bredon--Floyd theorem from compact groups $G$ (1960).

Topological mixing of the geodesic flow on convex projective manifolds

We introduce a natural subset of the unit tangent bundle of a convex projective manifold, the biproximal unit tangent bundle; it is closed and invariant under the geodesic flow, and we prove that the geodesic flow is topologically mixing on it whenever the manifold is irreducible. We also show that, for higher-rank, irreducible, compact convex projective manifolds, the geodesic flow is topologically mixing on each connected component of the non-wandering set.

A Hennings type invariant of $3$-manifolds from a topological Hopf superalgebra

We prove the unrolled superalgebra $\mathcal{U}_ξ^{H}\mathfrak{sl}(2|1)$ has a completion which is a ribbon superalgebra in a topological sense where $ξ$ is a root of unity of odd order. Using this ribbon superalgebra we construct its universal invariant of links. We use it to construct an invariant of $3$-manifolds of Hennings type.

Characterization and topological rigidity of Nobeling manifolds

We develop a theory of Nobeling manifolds similar to the theory of Hilbert space manifolds. We show that it reflects the theory of Menger manifolds developed by M. Bestvina and is its counterpart in the realm of complete spaces. In particular, the Nobeling manifold characterization conjecture is proven.

Topological finiteness for asymptotically nonnegatively curved manifolds

We prove that a class of asymptotically nonnegatively curved manifolds (in the sense of Abresch) satisfying some uniform Euclidean type volume growth conditions contains only finitely many homeomorphism types.

On the topological complexity of manifolds with abelian fundamental group

We find conditions which ensure that the topological complexity of a closed manifold $M$ with abelian fundamental group is nonmaximal, and see through examples that our conditions are sharp. This generalizes results of Costa and Farber on the topological complexity of spaces with small fundamental group. Relaxing the commutativity condition on the fundamental group, we also generalize results of Dranishnikov on the Lusternik-Schnirelmann category of the cofibre of the diagonal map $Δ: M \to M \times M$ for nonorientable surfaces by establishing the nonmaximality of this invariant for a large c…

On LS-category and topological complexity of connected sum

The Lusternik-Schnirelmann category and topological complexity are important invariants of manifolds (and more generally, topological spaces). We study the behavior of these invariants under the operation of taking the connected sum of manifolds. We give a complete answer for the LS-categoryof orientable manifolds, $\cat(M\# N)=\max\{\cat M,\cat N\}$. For topological complexity we prove the inequality $\TC (M\# N)\ge\max\{\TC M,\TC N\}$ for simply connected manifolds.

4维流形的稳定性范围

A stability range for topological 4-manifolds

本文提出了一种新的不变量，用于分类4维拓扑流形，并通过稳定化处理来改进分类方法。

Topological invariants of three-manifolds from U_q(osp(1|2n))

We create Resthetikhin-Turaev topological invariants of closed orientable three-manifolds from the quantum supergroup U_q(osp(1|2n)) at certain even roots of unity. To construct the invariants we develop tensor product theorems for finite dimensional modules of U_q(osp(1|2n)) at roots of unity.

某些完备仿射流形的拓扑体积

Topological volumes of certain complete affine manifolds

本文通过估计基本群含无限顺从正规子群的完备仿射流形的顺从范畴，证明其单纯体积为零，并进一步得到稳定整系数单纯体积与最小体积熵消失，从而回答 Lück 的问题并验证积分逼近。

Topological 4-manifolds with right-angled Artin fundamental groups

We classify closed, topological spin$^+$ 4-manifolds with fundamental group $π$ of cohomological dimension $\leq 3$ (up to s-cobordism), after stabilization by connected sum with at most $b_3(π)$ copies of $S^2\times S^2$. In general we must also assume that $π$ also satisfies certain K-theory and assembly map conditions. Examples for which these conditions hold include the torsion-free fundamental groups of 3-manifolds and all right-angled Artin groups whose defining graphs have no 4-cliques.