Search Results for author: Lijie Chen

Found 8 papers, 0 papers with code

Near-Optimal Two-Pass Streaming Algorithm for Sampling Random Walks over Directed Graphs

no code implementations22 Feb 2021 Lijie Chen, Gillat Kol, Dmitry Paramonov, Raghuvansh Saxena, Zhao Song, Huacheng Yu

In addition, we show a similar $\tilde{\Theta}(n \cdot \sqrt{L})$ bound on the space complexity of any algorithm (with any number of passes) for the related problem of sampling an $L$-step random walk from every vertex in the graph.

Data Structures and Algorithms Computational Complexity

On Distributed Differential Privacy and Counting Distinct Elements

no code implementations21 Sep 2020 Lijie Chen, Badih Ghazi, Ravi Kumar, Pasin Manurangsi

We study the setup where each of $n$ users holds an element from a discrete set, and the goal is to count the number of distinct elements across all users, under the constraint of $(\epsilon, \delta)$-differentially privacy: - In the non-interactive local setting, we prove that the additive error of any protocol is $\Omega(n)$ for any constant $\epsilon$ and for any $\delta$ inverse polynomial in $n$.

Open-Ended Question Answering

Nearly Optimal Sampling Algorithms for Combinatorial Pure Exploration

no code implementations4 Jun 2017 Lijie Chen, Anupam Gupta, Jian Li, Mingda Qiao, Ruosong Wang

We provide a novel instance-wise lower bound for the sample complexity of the problem, as well as a nontrivial sampling algorithm, matching the lower bound up to a factor of $\ln|\mathcal{F}|$.

Multi-Armed Bandits

Nearly Instance Optimal Sample Complexity Bounds for Top-k Arm Selection

no code implementations13 Feb 2017 Lijie Chen, Jian Li, Mingda Qiao

In the Best-$k$-Arm problem, we are given $n$ stochastic bandit arms, each associated with an unknown reward distribution.

Towards Instance Optimal Bounds for Best Arm Identification

no code implementations22 Aug 2016 Lijie Chen, Jian Li, Mingda Qiao

$H(I)=\sum_{i=2}^n\Delta_{[i]}^{-2}$ is the complexity of the instance.

Open Problem: Best Arm Identification: Almost Instance-Wise Optimality and the Gap Entropy Conjecture

no code implementations27 May 2016 Lijie Chen, Jian Li

The best arm identification problem (BEST-1-ARM) is the most basic pure exploration problem in stochastic multi-armed bandits.

Multi-Armed Bandits

Pure Exploration of Multi-armed Bandit Under Matroid Constraints

no code implementations23 May 2016 Lijie Chen, Anupam Gupta, Jian Li

In a Best-Basis instance, we are given $n$ stochastic arms with unknown reward distributions, as well as a matroid $\mathcal{M}$ over the arms.

On the Optimal Sample Complexity for Best Arm Identification

no code implementations12 Nov 2015 Lijie Chen, Jian Li

The $i$th arm has a reward distribution $D_i$ with an unknown mean $\mu_{i}$.

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