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We present an affine-invariant random walk for drawing uniform random samples from a convex body $\mathcal{K} \subset \mathbb{R}^n$ that uses maximum volume inscribed ellipsoids, known as John's ellipsoids, for the proposal distribution.…

Machine Learning · Statistics 2020-07-24 Adam Gustafson , Hariharan Narayanan

We propose a computationally efficient random walk on a convex body which rapidly mixes and closely tracks a time-varying log-concave distribution. We develop general theoretical guarantees on the required number of steps; this number can…

Machine Learning · Statistics 2013-09-25 Hariharan Narayanan , Alexander Rakhlin

The theory of rapid mixing random walks plays a fundamental role in the study of modern randomised algorithms. Usually, the mixing time is measured with respect to the worst initial position. It is well known that the presence of…

Probability · Mathematics 2024-01-30 Alberto Espuny Díaz , Patrick Morris , Guillem Perarnau , Oriol Serra

We present a Markov chain (Dikin walk) for sampling from a convex body equipped with a self-concordant barrier, whose mixing time from a "central point" is strongly polynomial in the description of the convex set. The mixing time of this…

Data Structures and Algorithms · Computer Science 2015-11-17 Hariharan Narayanan

We introduce a Markov chain for sampling from the uniform distribution on a Riemannian manifold $\mathcal{M}$, which we call the $\textit{geodesic walk}$. We prove that the mixing time of this walk on any manifold with positive sectional…

Probability · Mathematics 2017-11-28 Oren Mangoubi , Aaron Smith

We present a new random walk for uniformly sampling high-dimensional convex bodies. It achieves state-of-the-art runtime complexity with stronger guarantees on the output than previously known, namely in R\'enyi divergence (which implies…

Data Structures and Algorithms · Computer Science 2026-03-23 Yunbum Kook , Santosh S. Vempala , Matthew S. Zhang

We present a faster algorithm to generate a warm start for sampling an arbitrary logconcave density specified by an evaluation oracle, leading to the first sub-cubic sampling algorithms for inputs in (near-)isotropic position. A long line…

Data Structures and Algorithms · Computer Science 2025-05-06 Yunbum Kook , Santosh S. Vempala

In this paper we study random walks on dynamical random environments in $1 + 1$ dimensions. Assuming that the environment is invariant under space-time shifts and fulfills a mild mixing hypothesis, we establish a law of large numbers and a…

Probability · Mathematics 2018-05-25 Oriane Blondel , Marcelo R. Hilario , Augusto Teixeira

We study the problem of drawing samples from a logconcave distribution truncated on a polytope, motivated by computational challenges in Bayesian statistical models with indicator variables, such as probit regression. Building on interior…

Data Structures and Algorithms · Computer Science 2024-12-17 Minhui Jiang , Yuansi Chen

We propose the Hit-and-Run algorithm for planning and sampling problems in non-convex spaces. For sampling, we show the first analysis of the Hit-and-Run algorithm in non-convex spaces and show that it mixes fast as long as certain…

Computation · Statistics 2016-10-28 Yasin Abbasi-Yadkori , Peter L. Bartlett , Victor Gabillon , Alan Malek

We study whether the probability distribution of a discrete quantum walk can get arbitrarily close to uniform, given that the walk starts with a uniform superposition of the outgoing arcs of some vertex. We establish a characterization of…

Combinatorics · Mathematics 2024-07-03 Hanmeng Zhan

We analyze the hit-and-run algorithm for sampling uniformly from an isotropic convex body $K$ in $n$ dimensions. We show that the algorithm mixes in time $\tilde{O}(n^2/ \psi_n^2)$, where $\psi_n$ is the smallest isoperimetric constant for…

Probability · Mathematics 2022-12-02 Yuansi Chen , Ronen Eldan

We obtain a polynomial upper bound on the mixing time $T_{CHR}(\epsilon)$ of the coordinate Hit-and-Run random walk on an $n-$dimensional convex body, where $T_{CHR}(\epsilon)$ is the number of steps needed in order to reach within…

Data Structures and Algorithms · Computer Science 2022-04-12 Hariharan Narayanan , Piyush Srivastava

We show sufficient conditions under which the \textsc{BallWalk} algorithm mixes fast in a bounded connected subset of $\Real^n$. In particular, we show fast mixing if the space is the transformation of a convex space under a smooth…

Computation · Statistics 2016-11-29 Yasin Abbasi-Yadkori

A cyclic random walk is a random walk whose transition probabilities/rates can be written as a superposition of the empirical measures of a family of finite cycles. This identifies a convex set of models. We discuss the problem of…

Probability · Mathematics 2012-04-20 Davide Gabrielli , Carla Valente

The mixing time of a discrete-time quantum walk on the hypercube is considered. The mean probability distribution of a Markov chain on a hypercube is known to mix to a uniform distribution in time O(n log n). We show that the mean…

Quantum Physics · Physics 2008-04-17 F. L. Marquezino , R. Portugal , G. Abal , R. Donangelo

We consider the problem of sampling from a $d$-dimensional log-concave distribution $\pi(\theta) \propto \exp(-f(\theta))$ for $L$-Lipschitz $f$, constrained to a convex body with an efficiently computable self-concordant barrier function,…

Data Structures and Algorithms · Computer Science 2024-11-14 Yuzhou Gu , Nikki Lijing Kuang , Yi-An Ma , Zhao Song , Lichen Zhang

In dealing with thermal transport in composite systems, high contrast materials pose a special problem for numerical simulation: the time scale or step size in the high conductivity material must be much smaller than in the low conductivity…

Materials Science · Physics 2010-11-15 K. G. S. H. Gunawardana , Kieran Mullen , Dimitrios V. Papavassiliou

We prove results for random walks in dynamic random environments which do not require the strong uniform mixing assumptions present in the literature. We focus on the "environment seen from the walker"-process and in particular its…

Probability · Mathematics 2016-10-06 Stein Andreas Bethuelsen , Florian Völlering

We consider a random walk on a homogeneous space $G/\Lambda$ where $G$ is $\mathrm{SO}(2,1)$ or $\mathrm{SO}(3,1)$ and $\Lambda$ is a lattice. The walk is driven by a probability measure $\mu$ on $G$ whose support generates a Zariski-dense…

Dynamical Systems · Mathematics 2026-05-27 Timothée Bénard , Weikun He
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