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Justin Y. Chen

14 accepted papers

2025

Breaking the $n^{1.5}$ Additive Error Barrier for Private and Efficient Graph Sparsification via Private Expander Decomposition

ICML 2025poster

We study differentially private algorithms for graph cut sparsification, a fundamental problem in algorithms, privacy, and machine learning. While significant progress has been made, the best-known private and efficient cut sparsifiers on $n$-node graphs approximate each cut within $\widetilde{O}(n^…

Cited by 0SourcePDFScholar
2025

Differentially Private Gomory-Hu Trees

NeurIPS 2025poster

Given an undirected, weighted $n$-vertex graph $G = (V, E, w)$, a Gomory-Hu tree $T$ is a weighted tree on $V$ that preserves the Min-$s$-$t$-Cut between any pair of vertices $s, t \in V$. Finding cuts in graphs is a key primitive in problems such as bipartite matching, spectral and correlation clus…

Cited by 0SourceScholar
2025

Improved Approximations for Hard Graph Problems using Predictions

ICML 2025poster

We design improved approximation algorithms for NP-hard graph problems by incorporating predictions (e.g., learned from past data). Our prediction model builds upon and extends the $\varepsilon$-prediction framework by Cohen-Addad, d'Orsi, Gupta, Lee, and Panigrahi (NeurIPS 2024). We consider an ed…

Cited by 0SourcePDFScholar
2025

Learning-Augmented Frequent Directions

ICLR 2025spotlight

An influential paper of Hsu et al. (ICLR'19) introduced the study of learning-augmented streaming algorithms in the context of frequency estimation. A fundamental problem in the streaming literature, the goal of frequency estimation is to approximate the number of occurrences of items appearing in a…

Cited by 0SourcePDFScholar
2025

Scalable Private Partition Selection via Adaptive Weighting

ICML 2025poster

In the differentially private partition selection problem (a.k.a. set union, key discovery), users hold subsets of items from an unbounded universe. The goal is to output as many items as possible from the union of the users' sets while maintaining user-level differential privacy. Solutions to this…

Cited by 0SourcePDFScholar
2024

Evaluating the World Model Implicit in a Generative Model

NeurIPS 2024spotlight

Recent work suggests that large language models may implicitly learn world models. How should we assess this possibility? We formalize this question for the case where the underlying reality is governed by a deterministic finite automaton. This includes problems as diverse as simple logical reasonin…

2024

Statistical-Computational Trade-offs for Density Estimation

NeurIPS 2024poster

We study the density estimation problem defined as follows: given $k$ distributions $p_1, \ldots, p_k$ over a discrete domain $[n]$, as well as a collection of samples chosen from a "query" distribution $q$ over $[n]$, output $p_i$ that is "close" to $q$. Recently Aamand et al. gave the first and o…

Cited by 0SourcePDFScholar
2023

Constant Approximation for Individual Preference Stable Clustering

NeurIPS 2023spotlight

Individual preference (IP) stability, introduced by Ahmadi et al. (ICML 2022), is a natural clustering objective inspired by stability and fairness constraints. A clustering is $\alpha$-IP stable if the average distance of every data point to its own cluster is at most $\alpha$ times the average dis…

Cited by 5SourcePDFScholar
2023

Data Structures for Density Estimation

ICML 2023poster

We study statistical/computational tradeoffs for the following density estimation problem: given $k$ distributions $v_1, \ldots, v_k$ over a discrete domain of size $n$, and sampling access to a distribution $p$, identify $v_i$ that is "close" to $p$. Our main result is the first data structure that…

2023

Improved Frequency Estimation Algorithms with and without Predictions

NeurIPS 2023spotlight

Estimating frequencies of elements appearing in a data stream is a key task in large-scale data analysis. Popular sketching approaches to this problem (e.g., CountMin and CountSketch) come with worst-case guarantees that probabilistically bound the error of the estimated frequencies for any possible…

Cited by 13SourcePDFScholar
2022

Exponentially Improving the Complexity of Simulating the Weisfeiler-Lehman Test with Graph Neural Networks

NeurIPS 2022accept

Recent work shows that the expressive power of Graph Neural Networks (GNNs) in distinguishing non-isomorphic graphs is exactly the same as that of the Weisfeiler-Lehman (WL) graph test. In particular, they show that the WL test can be simulated by GNNs. However, those simulations involve neural netw…

Cited by 23SourcePDFScholar
2022

Triangle and Four Cycle Counting with Predictions in Graph Streams

ICLR 2022poster

We propose data-driven one-pass streaming algorithms for estimating the number of triangles and four cycles, two fundamental problems in graph analytics that are widely studied in the graph data stream literature. Recently, Hsu et al. (2019) and Jiang et al. (2020) applied machine learning technique…

Cited by 35SourcePDFScholar