I. L. Chatterji, G. A. Niblo
We explain how to adapt a construction of M. Sageev's to construct a proper action on a CAT(0) cube complex starting from a proper action on a wall space, and use this to deduce that if G is a group containing an amenable subgroup H of super-polynomial growth and G acts properly on a space with walls then there are arbitrarily large families of walls in the wall space which pairwise cross.
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
We define an integer-valued invariant of special cube complexes called the genus, and prove that having genus one characterizes special cube complexes with abelian fundamental group. Using the genus, we obtain a new proof that the fundamental group of a special cube complex is either free abelian or surjects onto a non-cyclic free group. We also investigate automorphisms of special cube complexes, and give a new geometric proof that the Torelli subgroup for a right-angled Artin group is torsion-free.
Spatial Cube Complexes
本文为直角 Artin 群无扭曲外空间的脊柱提供了新几何刻画，将其实现为基于超平面坍缩定义的新一类局部 CAT(0) 空间立方复形范畴的自然单纯复形。
We introduce a $\mathbb{Z}$-valued cross ratio on Roller boundaries of ${\rm CAT(0)}$ cube complexes. We motivate its relevance by showing that every cross-ratio preserving bijection of Roller boundaries uniquely extends to a cubical isomorphism. Our results are strikingly general and even apply to infinite dimensional, locally infinite cube complexes with trivial automorphism group.
CAT(0) cube complexes and asymptotically rigid mapping class groups
本文研究由平面树加厚得到的无限穿孔曲面的渐近刚性映射类群，构造了一族其上可作用的 CAT(0) 立方复形，并确定了 Genevois、Lonjou 和 Urech 早先引入的立方复形为 CAT(0) 的条件。
Leighton's Theorem and Regular Cube Complexes
本研究将Leighton图覆盖定理推广至一类作为正则图自然推广的非正曲率特殊立方体复形，该类复形涵盖双曲与非双曲的CAT(0)立方体复形，拓展了定理的适用范围。
These notes grew out of two lectures I have given on CAT(0) cube complexes. I've tried to keep the material elementary and self-contained in order to keep the material easily accessible and to provide an elementary introduction on the topic for advanced bachelor students or early master students with little to no previous knowledge on geometric group theory or CAT(0) geometry.
We develop the foundations of the theory of relatively geometric actions of relatively hyperbolic groups on CAT(0) cube complexes, a notion introduced in our previous work [5]. In the relatively geometric setting we prove: full relatively quasi-convex subgroups are convex compact; an analog of Agol's Theorem; and a version of Haglund--Wise's Canonical Completion and Retraction.
In a seminal paper, Stallings introduced folding of morphisms of graphs. One consequence of folding is the representation of finitely-generated subgroups of a finite-rank free group as immersions of finite graphs. Stallings's methods allow one to construct this representation algorithmically, giving effective, algorithmic answers and proofs to classical questions about subgroups of free groups. Recently Dani--Levcovitz used Stallings-like methods to study subgroups of right-angled Coxeter groups, which act geometrically on CAT(0) cube complexes. In this paper we extend their techniques to fund…
Finite Stature in Graphs of Cube Complexes with Cyclonormal Edges
本文研究了具有 cyclonormal 边的立方复形图的有限 stature 性质，并在顶点群为超几何时推导出其虚拟特殊性。
In this paper, we study the geometry of cone-offs of CAT(0) cube complexes over a family of combinatorially convex subcomplexes, with an emphasis on their Gromov-hyperbolicity. A first application gives a direct cubical proof of the characterization of the (strong) relative hyperbolicity of right-angled Coxeter groups, which is a particular case of a result due to Behrstock, Caprace and Hagen. A second application gives the acylindrical hyperbolicity of $C'(1/4)-T(4)$ small cancellation quotients of free products.
Given a CAT(0) cube complex X, we show that if Aut(X) $\neq$ Isom(X) then there exists a full subcomplex of X which decomposes as a product with $\mathbb{R}^n$. As applications, we prove that if X is $δ$-hyperbolic, cocompact and 1-ended, then Aut(X) $=$ Isom(X) unless X is quasi-isometric to $\mathbb{H}^2$, and extend the rank-rigidity result of Caprace-Sageev to any lattice $ Γ\leq$ Isom(X).
We address the question of whether the property of being virtually special (in the sense of Haglund and Wise) is algorithmically decidable for finite, non-positively curved cube complexes. Our main theorem shows that it cannot be decided locally, i.e. by examining one hyperplane at a time. Specifically, we prove that there does not exist an algorithm that, given a compact non-positively squared 2-complex X and a hyperplane H in X can decide whether or not there is a finite-sheeted cover of X in which no lift of H self-osculates.
Groups acting on CAT(0) cube complexes with uniform exponential growth
研究作用于 CAT(0) 立方复形的群的一致指数增长，证明无全局不动点作用于方复形的群有一致指数增长或稳定欧几里得子复形，推广前人工作并应用于 Higman 群和无三角形 Artin 群子群。
Polynomial filling functions of sublevel sets in $\mathrm{CAT}(0)$ cube complexes
本文给出判据确保 CAT(0) 立方复形高子水平集有多项式积分同调填充函数，并验证 Higman-Thompson 群满足，从而这些群在每度 k≥2 有多项式同调填充函数。
On the Girth of Groups acting on CAT(0) cube complexes
该研究给出有限维CAT(0)立方体复形自同构群的格有无限围长的充分条件，得到几何作用群的围长二择一定理，并构造反例说明该定理对紧作用的一般群类不成立。
Median quasimorphisms on CAT(0) cube complexes and their cup products
本文将自由群 Brooks 拟态射杯积的消没定理推广至 CAT(0) 立方体复形上的中位数拟态射，并应用于树作用群与直角 Artin 群。
The main technical result of this paper is to characterize the contracting isometries of a CAT(0) cube complex without any assumption on its local finiteness. Afterwards, we introduce the combinatorial boundary of a CAT(0) cube complex, and we show that contracting isometries are strongly related to isolated points at infinity, when the complex is locally finite. This boundary turns out to appear naturally in the context of Guba and Sapir's diagram groups, and we apply our main criterion to determine precisely when an element of a diagram group induces a contracting isometry on the associated …
Automorphisms of contact graphs of ${\rm CAT(0)}$ cube complexes
研究CAT(0)立方复形的自同构群与Hagen接触图的自同构群的等价性，揭示接触图与Kim-Koberda扩展图的差异。
We provide geometric conditions on a pair of hyperplanes of a CAT(0) cube complex that imply divergence bounds for the cube complex. As an application, we classify all right-angled Coxeter groups with quadratic divergence and show right-angled Coxeter groups cannot exhibit a divergence function between quadratic and cubic. This generalizes a theorem of Dani-Thomas that addressed the class of 2-dimensional right-angled Coxeter groups. As another application, we provide an inductive graph theoretic criteria on a right-angled Coxeter group's defining graph which allows us to recognize arbitrary i…
Divisible cube complexes and finite-order automorphisms of RAAGs
研究了RAAGs有限阶自同构的固定子群的几何特征，发现这些子群是可除立方复形的基群，并指出表面群和右角Coxeter群的交换子群是此类固定子群的例子。
Borel asymptotic dimension of the Roller boundary of finite dimensional CAT(0) cube complexes
本文研究可数有限维 CAT(0) 立方体复形 Roller 紧化上的 Borel 中位数图，证明其 Borel 渐近维数不超过复形维数。
Let $S_g$ denote the closed orientable surface of genus $g$. We construct exponentially many mapping class group orbits of collections of $2g+1$ simple closed curves on $S_g$ which pairwise intersect exactly once, extending a result of the first author and further answering a question of Malestein-Rivin-Theran. To distinguish such collections up to the action of the mapping class group, we analyze their dual cube complexes in the sense of Sageev. In particular, we show that for any even $k$ between $\lfloor g/2 \rfloor$ and $g$, there exists such collections whose dual cube complexes have dime…
The Roller boundary is a well-known compactification of a CAT(0) cube complex X. When X is locally finite, essential, irreducible, non-Euclidean and admits a cocompact action by a group G, Nevo-Sageev show that a subset, B(X), of the Roller boundary is the realization of the Poisson boundary and that the action of G on B(X) is minimal and strongly proximal. Additionally, these authors show B(X) satisfies many other desirable dynamical and topological properties. In this article we give several equivalent characterizations for when B(X) is equal to the entire Roller boundary. As an application …
Random walks on spaces with hyperbolic properties tend to sublinearly track geodesic rays which point in certain hyperbolic-like directions. Qing-Rafi-Tiozzo recently introduced the sublinearly Morse boundary and proved that this boundary is a quasi-isometry invariant which captures a notion of generic direction in a broad context. In this article, we develop the geometric foundations of sublinear Morseness in the mapping class group and Teichmüller space. We prove that their sublinearly Morse boundaries are visibility spaces and admit continuous equivariant injections into the boundary of the…
In the presence of certain topological conditions, we provide lower bounds for the infimum of the length function associated to a collection of curves on Teichmüller space that depend on the dual cube complex associated to the collection, a concept due to Sageev. As an application of our bounds, we obtain estimates for the `longest' curve with $k$ self-intersections, complementing work of Basmajian \cite{basmajian}.
We show under weak hypotheses that $\partial X$, the Roller boundary of a finite dimensional CAT(0) cube complex $X$ is the Furstenberg-Poisson boundary of a sufficiently nice random walk on an acting group $Γ$. In particular, we show that if $Γ$ admits a nonelementary proper action on $X$, and $μ$ is a generating probability measure of finite entropy and finite first logarithmic moment, then there is a $μ$-stationary measure on $\partial X$ making it the Furstenberg-Poisson boundary for the $μ$-random walk on $Γ$. We also show that the support is contained in the closure of the regular points…
We give a proof to the following theorem, which is well-known among experts: A connected subcomplex $W$ of a finite dimensional CAT(0) cubed complex $X$ is convex if and only if Lk$(v, W)$ is a full subcomplex of Lk$(v, X)$ for every vertex $v$ of $W$.
To any semigroup presentation $\mathcal{P}= \langle Σ\mid \mathcal{R} \rangle$ and base word $w \in Σ^+$ may be associated a nonpositively curved cube complex $S(\mathcal{P},w)$, called a Squier complex, whose underlying graph consists of the words of $Σ^+$ equal to $w$ modulo $\mathcal{P}$ where two such words are linked by an edge when one can be transformed into the other by applying a relation of $\mathcal{R}$. A group is a diagram group if it is the fundamental group of a Squier complex. In this paper, we describe hyperplanes in these cube complexes. As a first application, we determine e…
We show that group actions on irreducible ${\rm CAT(0)}$ cube complexes with no free faces are uniquely determined by their $\ell^1$ length function. Actions are allowed to be non-proper and non-cocompact, as long as they are minimal and have no finite orbit in the visual boundary. This is, to our knowledge, the first length-spectrum rigidity result in a setting of non-positive curvature (with the exception of some particular cases in dimension 2 and symmetric spaces). As our main tool, we develop a notion of cross ratio on Roller boundaries of ${\rm CAT(0)}$ cube complexes. Inspired by result…
Injectivity, cubical approximations and equivariant wall structures beyond CAT(0) cube complexes
这篇几何群论综述一方面阐述了单射度量空间与Behrstock-Hagen-Sisto立方逼近定理两个前沿思想的影响，另一方面论证了多类测地度量空间的丰富等变壁结构，相关发现受前述理论启发。
We construct new families of quasimorphisms on many groups acting on CAT(0) cube complexes. These quasimorphisms have a uniformly bounded defect of 12, and they "see" all elements that act hyperbolically on the cube complex. We deduce that all such elements have stable commutator length at least 1/24. The group actions for which these results apply include the standard actions of right-angled Artin groups on their associated CAT(0) cube complexes. In particular, every non-trivial element of a right-angled Artin group has stable commutator length at least 1/24. These results make use of some ne…
Homotopy equivalent boundaries of cube complexes
本文研究有限维 CAT(0) 立方体复形的多种边界，通过 Roller 边界商上的偏序构造单纯 Roller 边界，并证明其与 Tits、单纯边界在同伦意义下 $Aut(X)$-等变等价，从而说明度量扰动不改变等变同伦类型。
Relatively geometric actions of Kähler groups on CAT(0) cube complexes
本文证明非均匀格点在CAT(0)立方复形上无相对几何作用，并推导出相关李群可公度性及Kähler群为曲面群的结论。
We give a generalized and self-contained account of Haglund-Paulin's wallspaces and Sageev's construction of the CAT(0) cube complex dual to a wallspace. We examine criteria on a wallspace leading to finiteness properties of its dual cube complex. Our discussion is aimed at readers wishing to apply these methods to produce actions of groups on cube complexes and understand their nature. We develop the wallspace ideas in a level of generality that facilitates their application. Our main result describes the structure of dual cube complexes arising from relatively hyperbolic groups. Let H_1,...,…
Rigidity phenomena and the statistical properties of group actions on $\text{CAT}(0)$ cube complexes
本文通过构造有限状态自动机结合热力学形式，研究满足特定条件的群在$\text{CAT}(0)$立方复形上立方作用的标记长度谱，证明Manhattan曲线的解析凸性与大偏差定理，揭示群作用的刚性与统计性质。
Boundary rigidity of 3D CAT(0) cube complexes
研究离散版边界刚性问题，证明有限3D CAT(0)立方复形及任意有限2D CAT(0)立方复形的组合类型均可由其边界距离重构，推广并加强了Haslegrave的结论。
Sphere-bases are constructed for the $\mathbb{Z}_2$ vector space formed by the $k$-dimensional subcomplexes, of $n$-simplex (or $n$-cube), for which every $(k{-}1)$-face is contained in a positive even number of $k$-cells; addition is symmetric difference of the corresponding sets of $k$-cells. The bases consist of the boundaries of an algorithmically-specified family of $k{+}1$-simplexes or $k{+}1$-cubes. Geometric properties of these bases are investigated.
We discuss a problem posed by Gersten: Is every automatic group which does not contain Z+Z subgroup, hyperbolic? To study this question, we define the notion of "n-tracks of length n", which is a structure like Z+Z, and prove its existence in the non-hyperbolic automatic groups with mild conditions. As an application, we show that if a group acts effectively, cellularly, properly discontinuously and cocompactly on a CAT(0) cube complex and its quotient is "weakly special", then the above question is answered affirmatively.
We investigate the Tits boundary of locally compact CAT(0) 2-complexes. In particular we show that away from the endpoints, a geodesic segment in the Tits boundary is the ideal boundary of an isometrically embedded Euclidean sector. As applications, we provide sufficient conditions for two points in the Tits boundary to be the endpoints of a geodesic in the 2-complex and for a group generated by two hyperbolic isometries to contain a free group. We also show that if two CAT(0) 2-complexes are quasi-isometric then the cores of their Tits boundaries are bi-Lipschitz.
Finite rank median spaces are a simultaneous generalisation of finite dimensional ${\rm CAT}(0)$ cube complexes and real trees. If $Γ$ is an irreducible lattice in a product of rank one simple Lie groups, we show that every action of $Γ$ on a complete, finite rank median space has a global fixed point. This is in sharp contrast with the behaviour of actions on infinite rank median spaces. The fixed point property is obtained as corollary to a superrigidity result; the latter holds for irreducible lattices in arbitrary products of compactly generated groups. In previous work, we introduced "Rol…
A toric cube is a subset of the standard cube defined by binomial inequalities. These basic semialgebraic sets are precisely the images of standard cubes under monomial maps. We study toric cubes from the perspective of topological combinatorics. Explicit decompositions as CW-complexes are constructed. Their open cells are interiors of toric cubes and their boundaries are subcomplexes. The motivating example of a toric cube is the edge-product space in phylogenetics, and our work generalizes results known for that space.
Curtain Characterization of Sublinearly Morse Geodesics in CAT(0) Spaces
本文证明每个 CAT(0) 空间的次线性 Morse 边界可连续嵌入某双曲空间的 Gromov 边界，利用帘幕机制给出多种刻画，并回答了 Petyt-Spriano-Zalloum 的多个问题。
We show that the n-homotopy category of connected (n+1)-dimensional Menger manifolds is isomorphic to the homotopy category of connected Hilbert cube manifolds whose k-dimensional homotopy groups are trivial for each k > n.
We prove that almost all arc complexes do not admit a CAT(0) metric with finitely many shapes, in particular any finite-index subgroup of the mapping class group does not preserve such a metric on the arc complex. We also show the analogous statement for all but finitely many disc complexes of handlebodies and free splitting complexes of free groups. The obstruction is combinatorial. These complexes are all hyperbolic and contractible but despite this we show that they satisfy no combinatorial isoperimetric inequality: for any n there is a loop of length 4 that only bounds discs consisting of …
In this article, I prove that full subcomplexes of CAT(0) simplicial 3-complexes inherit the non positive curvature condition, and describe a family of counterexamples that prove this result can not be extended to higher dimensions.
Polyhedral CAT(0) metrics on locally finite complexes
本文证明了局部有限 CAT(0) 复形在特定多面体度量下的树状性质，并建立了三角剖分流形允许 CAT(0) 度量与树状三角剖分之间的充要条件。
We show how to construct homology bases for certain CW complexes in terms of discrete Morse theory and cellular homology. We apply this technique to study certain subcomplexes of the half cube polytope studied in previous works. This involves constructing explicit complete acyclic Morse matchings on the face lattice of the half cube; this procedure may be of independent interest for other highly symmetric polytopes.
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。