A $(\log n)^{\Omega(1)}$ integrality gap for the Sparsest Cut SDP (2009)
Cheeger, Jeff, Kleiner, Bruce, Naor, Assaf
We show that the Goemans-Linial semidefinite relaxation of the Sparsest Cut problem with general demands has integrality gap $(\log n)^{\Omega(1)}$. This is achieved by exhibiting $n$-point metric...
Compression bounds for Lipschitz maps from the Heisenberg group to $L_1$ (2009)
Cheeger, Jeff, Kleiner, Bruce, Naor, Assaf
We prove a quantitative bi-Lipschitz nonembedding theorem for the Heisenberg group with its Carnot-Carath\'eodory metric and apply it to give a lower bound on the integrality gap of the...
Metric differentiation, monotonicity and maps to L^1 (2009)
We give a new approach to the infinitesimal structure of Lipschitz maps into L^1. As a first application, we give an alternative proof of the main theorem from an earlier paper, that the Heisenberg...
Rigidity of Schottky sets (2009)
Mario Bonk, Bruce Kleiner, Sergei Merenkov
Dedicated to the memory of Juha Heinonen. Abstract. We call a complement of a union of at least three disjoint (round) open balls in the unit sphere S n a Schottky set. We prove that every...
Rigidity of Schottky sets (2009)
Mario Bonk, Bruce Kleiner, Sergei Merenkov
American Journal of Mathematics - Volume 131, Number 2, April 2009
CHARACTERIZATION OF THE RADON-NIKODYM PROPERTY IN TERMS OF INVERSE LIMITS (2009)
Abstract. In this paper we clarify the relation between inverse systems, the Radon-Nikodym property, the Asymptotic Norming Property of James-Ho [JH81], and the GFDA spaces introduced in
Rigidity of Schottky sets (2008)
Mario Bonk, Bruce Kleiner, Sergei Merenkov
Abstract. We call a complement of a union of at least three disjoint open balls in the unit sphere S n a Schottky set. We prove that every quasisymmetric homeomorphism of a Schottky set of spherical...
INDUCED QUASI-ACTIONS: A REMARK (2008)
In this note we observe that the notion of an induced representation has an analog for quasi-actions, and give some applications. We will use the definitions and notation from [KL01]. 1.1. Induced...
A NEW PROOF OF GROMOV’S THEOREM ON GROUPS OF POLYNOMIAL GROWTH (2008)
Abstract. We give a proof of Gromov’s theorem that any finitely generated group of polynomial growth has a finite index nilpotent subgroup. The proof does not rely on the Montgomery-Zippin-Yamabe...
Erratum on "Hadamard spaces with isolated flats" (2008)
Hruska, G. Christopher, Kleiner, Bruce
The purpose of this erratum is to correct the proof of Theorem A.0.1 in the appendix to our article ``Hadamard spaces with isolated flats'' math.GR/0411232, which was jointly authored by Mohamad...
We prove the differentiability of Lipschitz maps X-->V, where X is a complete metric measure space satisfying a doubling condition and a Poincar\'e inequality, and V is a Banach space with the Radon...
THE WEAK HYPERBOLIZATION CONJECTURE FOR 3-DIMENSIONAL CAT(0) GROUPS (2008)
Michael Kapovich, Bruce Kleiner
Abstract. We prove a weak hyperbolization conjecture for CAT(0) 3-dimensional Poincaré duality groups. 1.
Abstract. This is one of a series of papers examining the interplay between differentiation theory for Lipschitz maps, X → V, and bi-Lipschitz nonembeddability, where X is a metric measure space...
Quasiflats in CAT(0) complexes (2008)
Bestvina, Mladen, Kleiner, Bruce, Sageev, Michah
We show that if X is a piecewise Euclidean 2-complex with a cocompact isometry group, then every 2-quasiflat in X is at finite Hausdorff distance from a subset which is locally flat outside a compact...
Ambrosio, Luigi, Kleiner, Bruce, Donne, Enrico Le
We consider sets of locally finite perimeter in Carnot groups. We show that if E is a set of locally finite perimeter in a Carnot group G, then for almost every x in G with respect to the perimeter...
Induced quasi-actions: a remark (2008)
Kleiner, Bruce, Leeb, Bernhard
In this note we observe that the notion of an induced representation has an analog for quasi-actions. We then use induced quasi-actions to refine some earlier rigidity results for product spaces.
Geometry and rigidity of mapping class groups (2008)
Behrstock, Jason, Kleiner, Bruce, Minsky, Yair, Mosher, Lee
We study the large scale geometry of mapping class groups MCG(S), using hyperbolicity properties of curve complexes. We show that any self quasi-isometry of MCG(S) (outside a few sporadic cases) is a...
Abstract. We study quasi-isometries between products of symmetric spaces and Euclidean buildings. The main results are that quasi-isometries preserve product structure, and in the irreducible higher...
Hyperbolic groups with low-dimensional boundary (2007)
Michael Kapovich, Bruce Kleiner
If a torsion-free hyperbolic group G has 1-dimensional boundary @1G, then @1G is a Menger curve or a Sierpinski carpet provided G does not split over a cyclic group. When
Christopher B. Croke, Bruce Kleiner
with nonpositive curvature and their ideal boundaries
Groups quasi-isometric to symmetric spaces (2007)
We determine the structure of finitely generated groups which are quasi-isometric to symmetric spaces of noncompact type, allowing Euclidean de Rham factors. If X is a symmetric space of noncompact...
A new proof of Gromov's theorem on groups of polynomial growth (2007)
We give a new proof of Gromov's theorem that any finitely generated group of polynomial growth has a finite index nilpotent subgroup. Unlike the original proof, it does not rely on the...
The asymptotic geometry of right-angled Artin groups, I (2007)
Bestvina, Mladen, Kleiner, Bruce, Sageev, Michah
We study atomic right-angled Artin groups -- those whose defining graph has no cycles of length less than five, and no separating vertices, separating edges, or separating vertex stars. We show that...
Characterization of the Radon-Nikodym Property in terms of inverse limits (2007)
We clarify the relation between inverse systems, the Radon-Nikodym property, the Asymptotic Norming Property of James-Ho, and the GFDA spaces introduced in our earlier paper on differentiability of...
Differentiating maps into L^1 and the geometry of BV functions (2006)
This is one of a series of papers examining the interplay between differentiation theory for Lipschitz maps, X-->V, and bi-Lipschitz nonembeddability, where X is a metric measure space and V is a...
Notes on Perelman's papers (2006)
These are detailed notes on Perelman's papers "The entropy formula for the Ricci flow and its geometric applications" and "Ricci flow with surgery on three-manifolds".
Rigidity of invariant convex sets in symmetric spaces (2006)
Kleiner, Bruce, Leeb, Bernhard
The main result implies that a proper convex subset of an irreducible higher rank symmetric space cannot have Zariski dense stabilizer.
On the differentiation of Lipschitz maps from metric measure spaces to Banach spaces (2006)
Abstract. We consider metric measure spaces satisfing a doubling condition and a Poincaré inequality in the upper gradient sense. We show that the results of [Che99] on differentiability of real...
Generalized differentiation and bi-Lipschitz nonembedding (2006)
Résumé. We consider Lipschitz mappings f: X → V, where X is a doubling metric measure space which satisfies a Poincaré inequality, and V is a Banach space. We show that earlier differentiability...
Coarse Alexander duality and duality groups (2005)
Kapovich, Michael, Kleiner, Bruce
We study discrete group actions on coarse Poincaré duality spaces, e.g., acyclic simplicial complexes which admit free cocompact group actions by Poincaré duality groups. When G is an (n−1)...
Rigidity of invariant convex sets in symmetric spaces (2004)
Kleiner, Bruce, Leeb, Bernhard
The main result implies that a proper convex subset of an irreducible higher rank symmetric space cannot have Zariski dense stabilizer.
Hadamard spaces with isolated flats (2004)
Hruska, G Christopher, Kleiner, Bruce
We explore the geometry of nonpositively curved spaces with isolated flats, and its consequences for groups that act properly discontinuously, cocompactly, and isometrically on such spaces. We prove...
Geometry of quasi-planes (2004)
Michael Kapovich, Bruce Kleiner
Abstract. In this paper we discuss metric cell complexes satisfying a coarse form of 2-dimensional Poincaré duality. We prove that such spaces are either Gromov-hyperbolic or have polynomial growth....
Rigidity for quasi-Fuchsian actions on negatively curved spaces (2004)
We prove that if $$G\curvearrowright X$$ is a convex cocompact isometric group action on a CAT(−1) space, and the limit set has Hausdorff and topological dimensions equal to 1, then the action...
Singularity structure in mean curvature flow of mean convex sets (2003)
Colding, Tobias H., Kleiner, Bruce
In this note we announce results on the mean curvature flow of mean convex sets in 3-dimensions. Loosely speaking, our results justify the naive picture of mean curvature flow where the only...
Quasi-hyperbolic planes in hyperbolic groups (2003)
The hyperbolic plane admits a quasi-isometric embedding into a hyperbolic group if and only if the group is not virtually free.
Van Kampen’s embedding obstruction for discrete groups (2002)
Kleiner, Bruce, Bestvina, Mladen, Kapovich, Michael
We give a lower bound to the dimension of a contractible manifold on which a given group can act properly discontinuously. In particular, we show that the n -fold product of nonabelian free groups...
Conformal dimension and Gromov hyperbolic groups with 2-sphere boundary (2002)
Suppose G is a Gromov hyperbolic group, and the boundary at infinity of G is quasisymmetrically homeomorphic to an Ahlfors Q-regular metric 2-sphere Z with Ahlfors regular conformal dimension Q. Then...
Rigidity for Quasi-Möbius Group Actions (2002)
If a group acts by uniformly quasi-Möbius homeomorphisms on a compact Ahlfors n-regular space of topological dimension n such that the induced action on the space of distinct triples is cocompact,...
Quasisymmetric parametrizations of two-dimensional metric spheres (2001)
We study metric spaces homeomorphic to the 2-sphere, and find conditions under which they are quasisymmetrically homeomorphic to the standard 2-sphere. As an application of our main theorem we show...
Van Kampen's embedding obstruction for discrete groups (2000)
Bestvina, Mladen, Kapovich, Michael, Kleiner, Bruce
We give a lower bound to the dimension of a contractible manifold on which a given group can act properly discontinuously. In particular, we show that the $n$-fold product of nonabelian free groups...
Rigidity for Quasi-Mobius group actions (2000)
Suppose G is a hyperbolic group whose boundary has topological dimension k. If the boundary is quasisymmetrically homeomorphic to an Ahlfors k-regular metric space, then, modulo a finite normal...
Van Kampen's embedding obstruction for discrete groups (2000)
Mladen Bestvina, Michael Kapovich, Bruce Kleiner
We give a lower bound to the dimension of a contractible manifold on which a given group can act properly discontinuously. In particular, we show that the n-fold product of nonabelian free groups...
Hyperbolic Groups With Low Dimensional Boundary (2000)
Michael Kapovich, Bruce Kleiner
If a torsion-free hyperbolic group G has 1-dimensional boundary @1G, then @1G is a Menger curve or a Sierpinski carpet provided G does not split over a cyclic group. When @1G is a Sierpinski carpet...
The geodesic flow of a nonpositively curved graph manifold (1999)
Croke, Christopher B., Kleiner, Bruce
We study discrete, cocompact, isometric actions of groups on Hadamard spaces, and the induced actions on ideal boundaries. For a class of groups generalizing fundamental groups of three-dimensional...
Coarse Alexander duality and duality groups (1999)
Kapovich, Michael, Kleiner, Bruce
We study discrete group actions on coarse Poincare duality spaces, e.g. acyclic simplicial complexes which admit free cocompact group actions by Poincare duality groups. When G is an (n-1)...
Coarse Alexander duality and duality groups, preprint (1999)
Michael Kapovich, Bruce Kleiner
We study discrete group actions on coarse Poincare duality spaces, e.g. acyclic simplicial complexes which admit free cocompact group actions by Poincare duality groups. When G is an (n − 1)...
Coarse Alexander duality and duality groups (1999)
We study discrete group actions on coarse Poincare duality spaces, e.g. acyclic simplicial complexes which admit free cocompact group actions by Poincare duality groups. When G is an (n \Gamma 1)...
Hyperbolic groups with 1-dimensional boundary (1998)
Kapovich, Michael, Kleiner, Bruce
If a torsion-free hyperbolic group G has 1-dimensional boundary, then the boundary is a Menger curve or a Sierpinski carpet provided G does not split over a cyclic group. When the boundary of G is a...
Separated nets in euclidean space and jacobians of bi-lipschitz maps (1998)
We show that there are separated nets in the Euclidean plane which are not biLipschitz equivalent to the integer lattice. The argument is based on the construction of a continuous function which is...
Separated nets in Euclidean space and Jacobians of biLipschitz maps (1997)
Burago, Dmitri, Kleiner, Bruce
We show that there are separated nets in the Euclidean plane which are not biLipschitz equivalent to the integer lattice. The argument is based on the construction of a continuous function which is...
Rigidity of quasi-isometries for symmetric spaces and Euclidean buildings (1997)
1.1 Background and statement of results An (L, C) quasi-isometry is a map Φ: X − → X ′ between metric spaces such that for all x1, x2 ∈ X
Separated Nets In Euclidean Space And Jacobians Of Bilipschitz Maps (1997)
. We show that there are separated nets in the Euclidean plane which are not biLipschitz equivalent to the integer lattice. The argument is based on the construction of a continuous function which is...
Groups quasi-isometric to symmetric spaces (1996)
Kleiner, Bruce, Leeb, Bernhard
We determine the structure of finitely generated groups which are quasi-isometric to symmetric spaces of noncompact type, allowing Euclidean de Rham factors If $X$ is a symmetric space of noncompact...
Quasi-isometries and the de Rham decomposition (1996)
Michael Kapovich, Bruce Kleiner, Bernhard Leeb
We study quasi-isometries \Phi : Q X i ! Q Y j of product spaces and find conditions on the X i , Y j which guarantee that the product structure is preserved. The main result applies to universal...