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48 results for Assouad dimension

Proves a theorem for Assouad dimension with applications to distance sets and radial projections.

problem Problems related to Assouad dimension and distance sets.
method General nonlinear projection theorem for Assouad dimension.
result Sharp estimates for sets with Assouad dimension less than 1 and exceptional set estimates.

We prove the dimension of any asymptotic cone over a metric space X does not exceed the asymptotic Assouad-Nagata dimension of X. This improves a result of Dranishnikov and Smith who showed that dim(Y) does not exceed asymptotic Assouad-Nagata dimension of X for all separable subsets Y of special asymptotic cones of X …

2006-10-10abs ↗pdf ↗

Paper determines Assouad-Nagata dimension for all minor-closed metrics.

problem Understanding the Assouad-Nagata dimension of minor-closed metrics.
method Using edge-weighted graphs and edge-deletion/contraction to model minor-closed metrics, determining their Assouad-Nagata dimension.
result Determined the Assouad-Nagata dimension for every minor-closed metric.

In the first part of the paper we show how to relate several dimension theories (asymptotic dimension with Higson property, asymptotic dimension of Gromov, and capacity dimension of Buyalo \cite{Buyalo1}) to Nagata-Assouad dimension. This is done by applying two functors on the Lipschitz category of metric spaces: micr…

2006-01-10abs ↗pdf ↗

In this work we study two problems about Assouad-Nagata dimension: 1) Is there a metric space of non zero Assouad-Nagata dimension such that all of its asymptotic cones are of Assouad-Nagata dimension zero? (Dydak and Higes) 2) Suppose GG is a locally finite group with a proper left invariant metric dGd_G. If $\dim_{A…

2007-11-09abs ↗pdf ↗

We prove that the asymptotic Assouad-Nagata dimension of a connected Lie group GG equipped with a left-invariant Riemannian metric coincides with its topological dimension of G/CG/C where CC is a maximal compact subgroup. To prove it we will compute the Assouad-Nagata dimension of connected solvable Lie groups and sem…

2009-10-23abs ↗pdf ↗

Given a metric space XX of finite asymptotic dimension, we consider a quasi-isometric invariant of the space called dimension function. The space is said to have asymptotic Assouad-Nagata dimension less or equal nn if there is a linear dimension function in this dimension. We prove that if XX is a tree-graded space …

2009-10-13abs ↗pdf ↗

Optimizes Lipschitz estimates for partitions of unity and characterizes spaces with Assouad-Nagata dimension.

problem Understanding the properties of partitions of unity and their Lipschitz bounds.
method Analyzes the standard partition of unity and its p\ell^p-generalizations, using the approximate midpoint property and Lebesgue number.
result Optimal Lipschitz bounds for partitions of unity and characterizes metric spaces with Assouad-Nagata dimension.

Paper studies asymptotic dimension and Assouad-Nagata dimension of graphs and surfaces.

problem Understanding the asymptotic dimension and Assouad-Nagata dimension of graphs and surfaces.
method Analyzes asymptotic dimension of graph metrics and applies to surfaces, proving dimension bounds.
result Proves that complete Riemannian surfaces have Assouad-Nagata dimension at most 2.

We discuss a variation of Gromov's notion of asymptotic dimension that was introduced and named Nagata dimension by Assouad. The Nagata dimension turns out to be a quasisymmetry invariant of metric spaces. The class of metric spaces with finite Nagata dimension includes in particular all doubling spaces, metric trees, …

2004-10-04abs ↗pdf ↗

Consider the wreath product HGH\wr G, where H1H\ne 1 is finite and GG is finitely generated. We show that the Assouad-Nagata dimension dimAN(HG)\dim_{AN}(H\wr G) of HGH\wr G depends on the growth of GG as follows: If the growth of GG is not bounded by a linear function, then dimAN(HG)=\dim_{AN}(H\wr G)=\infty, otherwise $\dim_{AN}…

2006-11-11abs ↗pdf ↗

For a large class of metric space X including discrete groups we prove that the asymptotic Assouad-Nagata dimension AN-asdim X of X coincides with the covering dimension dim(νLX)\dim(ν_L X) of the Higson corona of X with respect to the sublinear coarse structure on X. Then we apply this fact to prove the equality AN-asdim(X …

2006-07-06abs ↗pdf ↗

Given a function f ⁣:XYf\colon X\to Y of metric spaces, its {\it asymptotic dimension} $\asdim(f)$ is the supremum of $\asdim(A)$ such that AXA\subset X and $\asdim(f(A))=0$. Our main result is \begin{Thm} \label{ThmAInAbstract} $\asdim(X)\leq \asdim(f)+\asdim(Y)$ for any large scale uniform function f ⁣:XYf\colon X\to Y. \end…

2006-05-16abs ↗pdf ↗

The paper extends statistical estimation techniques under differential privacy.

problem Establishing sample complexity bounds for estimation tasks under differential privacy.
method Proposes analogues of Le Cam's method, Fano's inequality, and Assouad's lemma under central differential privacy.
result Optimal sample complexity bounds for discrete distribution estimation under total variation and 2\ell_2 distances.

We relate generalized Lebesgue decompositions of measures in terms of curve fragments (Alberti representations) and Weaver derivations. This correspondence leads to a geometric characterization of the local norm on the Weaver cotangent bundle of a metric measure space (X,μ)(X,μ): the local norm of a form dfdf sees how fas…

2013-11-11abs ↗pdf ↗

We prove the equivalence between a relative bottleneck property and being quasi-isometric to a tree-graded space. As a consequence, we deduce that the quasi-trees of spaces defined axiomatically by Bestvina-Bromberg-Fujiwara are quasi-isometric to tree-graded spaces. Using this we prove that mapping class groups quasi-…

2012-07-09abs ↗pdf ↗

New lower bounds for private covariance estimation of Gaussian distributions are proven.

problem Proving tight lower bounds for private estimation tasks under differential privacy.
method Generalized fingerprinting method for exponential families and private Assouad method.
result Tight lower bounds for private covariance estimation in Frobenius and spectral norms.

The purpose of the paper is to characterize the dimension of sublinear Higson corona νL(X)ν_L(X) of XX in terms of Lipschitz extensions of functions: Theorem: Suppose (X,d)(X,d) is a proper metric space. The dimension of the sublinear Higson corona νL(X)ν_L(X) of XX is the smallest integer m0m\ge 0 with the following property…

2006-08-28abs ↗pdf ↗

Unified framework for lower bounds in interactive decision making.

problem Challenges in interactive decision making, especially bandits and reinforcement learning.
method Interactive Fano method and Fractional Covering Number.
result Unified characterization of learnability for stochastic bandit problems and tight lower bounds for interactive decision making.

Study minimax regret in bilateral trade with heavy-tailed valuations.

problem Minimizing regret in bilateral trade with infinite variance valuations.
method Extended self-bounding property, truncated-mean estimation, epoch-based algorithm.
result Achieves regret bound of O(T12β(p1)/(βp+d(p1)))O(T^{1-2β(p-1)/(βp + d(p-1))}) under specific conditions.

Optimizes budgeted evaluations of LLMs by allocating queries to judges efficiently.

problem Evaluating LLMs with heterogeneous judges and varying costs and reliability.
method Formalizes and analyzes budgeted heteroskedastic multi-judge estimation, proposing EST-IVWE for practical implementation.
result EST-IVWE matches the oracle IVWE rate up to lower-order terms in the budget and is instance-optimal.

Defines and classifies Thurston geometries and connects simplicial volume to Kodaira dimension.

problem Classifying Thurston geometries and understanding their properties.
method Introduces an axiomatic definition for the Kodaira dimension and studies its compatibility with traditional notions.
result Establishes a connection between the simplicial volume and the holomorphic Kodaira dimension, showing implications for smooth Kähler 3-folds.

Paper relates asymptotic dimension to cofinal dimension using coarse proximities.

problem Relating asymptotic dimension to cofinal dimension in metric spaces.
method Introducing coarse proximities and inverse limit constructions.
result Asymptotic dimension is bounded by coarse cofinal dimension and cofinal dimension of Higson corona.

Our goal in this paper is to develop an effective estimator of fractal dimension. We survey existing ideas in dimension estimation, with a focus on the currently popular method of Grassberger and Procaccia for the estimation of correlation dimension. There are two major difficulties in estimation based on this method. …

2013-12-09abs ↗pdf ↗

We introduce a new quasi-isometry invariant of metric spaces called the hyperbolic dimension, hypdim, which is a version of the Gromov's asymptotic dimension, asdim. The hyperbolic dimension is at most the asymptotic dimension, however, unlike the asymptotic dimension, the hyperbolic dimension of any Euclidean space R^…

2004-04-29abs ↗pdf ↗

This paper studies three aspects around dimension datum: (1), a generalization of the dimension datum, which we call the tau-dimension datum; (2), dimension data of disconnected subgroups; (3), compactness of isospectral sets of normal homogeneous spaces.

2018-03-16abs ↗pdf ↗

Random walks on Fuchsian Schottky groups have harmonic measures with lower dimension.

problem Understanding the dimensionality of harmonic measures for random walks.
method Analyzing finite range random walks on Fuchsian Schottky groups.
result Harmonic measures have dimension strictly less than the limit set's Hausdorff dimension.

The study finds limits on dimensions of certain scales and fields for conformal manifolds.

problem Limits on dimensions of almost Einstein scales and normal conformal Killing fields for conformal manifolds.
method Analyzes the submaximal dimensions of spaces of almost Einstein scales and normal conformal Killing fields for connected conformal manifolds, considering different signatures and dimensions.
result Upper bounds on dimensions of almost Einstein scales and normal conformal Killing fields are determined, with examples provided for submaximal dimensions.

Model complexity is an important factor to consider when selecting among graphical models. When all variables are observed, the complexity of a model can be measured by its standard dimension, i.e. the number of independent parameters. When hidden variables are present, however, standard dimension might no longer be ap…

2012-12-12abs ↗pdf ↗

Many 0/1 datasets have a very large number of variables; on the other hand, they are sparse and the dependency structure of the variables is simpler than the number of variables would suggest. Defining the effective dimensionality of such a dataset is a nontrivial problem. We consider the problem of defining a robust m…

2019-02-04abs ↗pdf ↗

We prove that for geometrically finite groups cohomological dimension of the direct product of a group with itself equals 2 times the cohomological dimension dimension of the group.

2019-02-08abs ↗pdf ↗

Estimates dimension of subsets from random samples, proving consistency.

problem Estimating the dimension of a compact subset from random samples.
method Consistency proofs for Minkowski, correlation, and pointwise dimensions using empirical volume function.
result Statistical consistency of estimators for various dimension notions.