← Search

Chiyuan Zhang

40 accepted papers

2025

Balls-and-Bins Sampling for DP-SGD

AISTATS 2025oral

We introduce the _Balls-and-Bins_ sampling for differentially private (DP) optimization methods such as DP-SGD. While it has been common practice to use some form of shuffling in DP-SGD implementations, privacy accounting algorithms have typically assumed that Poisson subsampling is used instead. Re…

Cited by 0SourceScholar
2025

Exploring and Mitigating Adversarial Manipulation of Voting-Based Leaderboards

ICML 2025oral

It is now common to evaluate Large Language Models (LLMs) by having humans manually vote to evaluate model outputs, in contrast to typical benchmarks that evaluate knowledge or skill at some particular task. Chatbot Arena, the most popular benchmark of this type, ranks models by asking users to sele…

Cited by 4SourcePDFScholar
2025

Fantastic Copyrighted Beasts and How (Not) to Generate Them

ICLR 2025poster

Recent studies show that image and video generation models can be prompted to reproduce copyrighted content from their training data, raising serious legal con- cerns about copyright infringement. Copyrighted characters (e.g., Mario, Batman) present a significant challenge: at least one lawsuit has…

Cited by 12SourcePDFScholar
2025

MATH-Perturb: Benchmarking LLMs' Math Reasoning Abilities against Hard Perturbations

ICML 2025poster

Large language models have demonstrated impressive performance on challenging mathematical reasoning tasks, which has triggered the discussion of whether the performance is achieved by true reasoning capability or memorization. To investigate this question, prior work has constructed mathematical be…

2025

MUSE: Machine Unlearning Six-Way Evaluation for Language Models

ICLR 2025poster

Language models (LMs) are trained on vast amounts of text data, which may include private and copyrighted content. Data owners may request the removal of their data from a trained model due to privacy or copyright concerns. However, exactly unlearning only these datapoints (i.e., retraining with the…

Cited by 52SourcePDFScholar
2025

Private Hyperparameter Tuning with Ex-Post Guarantee

NeurIPS 2025spotlight

The conventional approach in differential privacy (DP) literature formulates the privacy-utility tradeoff with a "privacy-first" perspective: for a predetermined level of privacy, a certain utility is achievable. However, practitioners often operate under a "utility-first" paradigm, prioritizing a…

Cited by 0SourceScholar
2025

Quantifying Cross-Modality Memorization in Vision-Language Models

NeurIPS 2025poster

Understanding what and how neural networks memorize during training is crucial, both from the perspective of unintentional memorization of potentially sensitive information and from the standpoint of effective knowledge acquisition for real-world, knowledge-intensive tasks. While previous studies pr…

Cited by 0SourceScholar
2025

Scaling Embedding Layers in Language Models

NeurIPS 2025poster

We propose SCONE (**S**calable, **C**ontextualized, **O**ffloaded, **N**-gram **E**mbedding), a new method for extending input embedding layers to enhance language model performance. To avoid increased decoding costs, SCONE retains the original vocabulary while introducing embeddings for a set of fr…

Cited by 0SourceScholar
2025

Scaling Laws for Differentially Private Language Models

ICML 2025poster

Scaling laws have emerged as important components of large language model (LLM) training as they can predict performance gains through scale, and provide guidance on important hyper-parameter choices that would otherwise be expensive. LLMs also rely on large, high-quality training datasets, like tho…

Cited by 2SourcePDFScholar
2025

Unlearn and Burn: Adversarial Machine Unlearning Requests Destroy Model Accuracy

ICLR 2025poster

Machine unlearning algorithms, designed for selective removal of training data from models, have emerged as a promising approach to growing privacy concerns. In this work, we expose a critical yet underexplored vulnerability in the deployment of unlearning systems: the assumption that the data reque…

Cited by 1SourcePDFScholar
2024

Evaluating Copyright Takedown Methods for Language Models

NeurIPS 2024poster

Language models (LMs) derive their capabilities from extensive training on diverse data, including copyrighted material. These models can memorize and generate content similar to their training data, potentially risking legal issues like copyright infringement. Therefore, model creators are motivat…

Cited by 21SourcePDFScholar
2024

How Private are DP-SGD Implementations?

ICML 2024oral

We demonstrate a substantial gap between the privacy guarantees of the Adaptive Batch Linear Queries (ABLQ) mechanism under different types of batch sampling: (i) Shuffling, and (ii) Poisson subsampling; the typical analysis of Differentially Private Stochastic Gradient Descent (DP-SGD) follows by i…

Cited by 16SourcePDFScholar
2024

LabelDP-Pro: Learning with Label Differential Privacy via Projections

ICLR 2024poster

Label differentially private (label DP) algorithms seek to preserve the privacy of the labels in a training dataset in settings where the features are known to the adversary. In this work, we study a new family of label DP training algorithms. Unlike most prior label DP algorithms that have been bas…

Cited by 0SourcePDFScholar
2024

Scalable DP-SGD: Shuffling vs. Poisson Subsampling

NeurIPS 2024poster

We provide new lower bounds on the privacy guarantee of _multi-epoch_ Adaptive Batch Linear Queries (ABLQ) mechanism with _shuffled batch sampling_, demonstrating substantial gaps when compared to _Poisson subsampling_; prior analysis was limited to a single epoch. Since the privacy analysis of Diff…

Cited by 7SourcePDFScholar
2023

Can Neural Network Memorization Be Localized?

ICML 2023poster

Recent efforts at explaining the interplay of memorization and generalization in deep overparametrized networks have posited that neural networks *memorize* ``hard'' examples in the final few layers of the model. Memorization refers to the ability to correctly predict on *atypical* examples of the t…

2023

Counterfactual Memorization in Neural Language Models

NeurIPS 2023spotlight

Modern neural language models that are widely used in various NLP tasks risk memorizing sensitive information from their training data. Understanding this memorization is important in real world applications and also from a learning-theoretical perspective. An open question in previous studies of la…

Cited by 172SourcePDFScholar
2023

Measuring Forgetting of Memorized Training Examples

ICLR 2023poster

Machine learning models exhibit two seemingly contradictory phenomena: training data memorization and various forms of forgetting. In memorization, models overfit specific training examples and become susceptible to privacy attacks. In forgetting, examples which appeared early in training are forgot…

Cited by 112SourcePDFScholar
2023

On User-Level Private Convex Optimization

ICML 2023poster

We introduce a new mechanism for stochastic convex optimization (SCO) with user-level differential privacy guarantees. The convergence rates of this mechanism are similar to those in the prior work of Levy et al. 2021 and Narayanan et al. 2022, but with two important improvements. Our mechanism does…

Cited by 14SourcePDFScholar
2023

Optimal Unbiased Randomizers for Regression with Label Differential Privacy

NeurIPS 2023poster

We propose a new family of label randomizers for training _regression_ models under the constraint of label differential privacy (DP). In particular, we leverage the trade-offs between bias and variance to construct better label randomizers depending on a privately estimated prior distribution over…

Cited by 4SourcePDFScholar
2023

Quantifying Memorization Across Neural Language Models

ICLR 2023top-25%

Large language models (LMs) have been shown to memorize parts of their training data, and when prompted appropriately, they will emit the memorized training data verbatim. This is undesirable because memorization violates privacy (exposing user data), degrades utility (repeated easy-to-memorize text…

Cited by 776SourcePDFScholar
2023

Regression with Label Differential Privacy

ICLR 2023poster

We study the task of training regression models with the guarantee of _label_ differential privacy (DP). Based on a global prior distribution of label values, which could be obtained privately, we derive a label DP randomization mechanism that is optimal under a given regression loss function. We pr…

Cited by 17SourcePDFScholar
2023

Sparsity-Preserving Differentially Private Training of Large Embedding Models

NeurIPS 2023poster

As the use of large embedding models in recommendation systems and language applications increases, concerns over user data privacy have also risen. DP-SGD, a training algorithm that combines differential privacy with stochastic gradient descent, has been the workhorse in protecting user privacy wi…

Cited by 5SourcePDFScholar
2023

User-Level Differential Privacy With Few Examples Per User

NeurIPS 2023oral

Previous work on user-level differential privacy (DP) [Ghazi et al. NeurIPS 2021, Bun et al. STOC 2023] obtained generic algorithms that work for various learning tasks. However, their focus was on the *example-rich* regime, where the users have so many examples that each user could themselves solve…

Cited by 17SourcePDFScholar
2022

Deduplicating Training Data Makes Language Models Better

ACL 2022long

We find that existing language modeling datasets contain many near-duplicate examples and long repetitive substrings. As a result, over 1% of the unprompted output of language models trained on these datasets is copied verbatim from the training data. We develop two tools that allow us to deduplicat…

2022

Just Fine-tune Twice: Selective Differential Privacy for Large Language Models

EMNLP 2022main

Protecting large language models from privacy leakage is becoming increasingly crucial with their wide adoption in real-world products. Yet applying *differential privacy* (DP), a canonical notion with provable privacy guarantees for machine learning models, to those models remains challenging due t…

2022

Learning to Reason with Neural Networks: Generalization, Unseen Data and Boolean Measures

NeurIPS 2022accept

This paper considers the Pointer Value Retrieval (PVR) benchmark introduced in [ZRKB21], where a `reasoning' function acts on a string of digits to produce the label. More generally, the paper considers the learning of logical functions with gradient descent (GD) on neural networks. It is first show…

2022

The Privacy Onion Effect: Memorization is Relative

NeurIPS 2022accept

Machine learning models trained on private datasets have been shown to leak their private data. Recent work has found that the average data point is rarely leaked---it is often the outlier samples that are subject to memorization and, consequently, leakage. We demonstrate and analyze an Onion Effect…

Cited by 122SourcePDFScholar
2022

Understanding and Improving Robustness of Vision Transformers through Patch-based Negative Augmentation

NeurIPS 2022accept

We investigate the robustness of vision transformers (ViTs) through the lens of their special patch-based architectural structure, i.e., they process an image as a sequence of image patches. We find that ViTs are surprisingly insensitive to patch-based transformations, even when the transformation l…

Cited by 51SourcePDFScholar
2021

Characterizing Structural Regularities of Labeled Data in Overparameterized Models

ICML 2021oral

Humans are accustomed to environments that contain both regularities and exceptions. For example, at most gas stations, one pays prior to pumping, but the occasional rural station does not accept payment in advance. Likewise, deep neural networks can generalize across instances that share common pat…

Cited by 119SourcePDFScholar
2021

Deep Learning with Label Differential Privacy

NeurIPS 2021poster

The Randomized Response (RR) algorithm is a classical technique to improve robustness in survey aggregation, and has been widely adopted in applications with differential privacy guarantees. We propose a novel algorithm, Randomized Response with Prior (RRWithPrior), which can provide more accurate r…

Cited by 182SourcePDFScholar
2021

Do Vision Transformers See Like Convolutional Neural Networks?

NeurIPS 2021poster

Convolutional neural networks (CNNs) have so far been the de-facto model for visual data. Recent work has shown that (Vision) Transformer models (ViT) can achieve comparable or even superior performance on image classification tasks. This raises a central question: how are Vision Transformers solvin…

Cited by 1303SourcePDFScholar
2021

Understanding Invariance via Feedforward Inversion of Discriminatively Trained Classifiers

ICML 2021spotlight

A discriminatively trained neural net classifier can fit the training data perfectly if all information about its input other than class membership has been discarded prior to the output layer. Surprisingly, past research has discovered that some extraneous visual detail remains in the unnormalized…

Cited by 7SourcePDFScholar
2020

Identity Crisis: Memorization and Generalization Under Extreme Overparameterization

ICLR 2020poster

We study the interplay between memorization and generalization of overparameterized networks in the extreme case of a single training example and an identity-mapping task. We examine fully-connected and convolutional networks (FCN and CNN), both linear and nonlinear, initialized randomly and then tr…

Cited by 112SourceScholar
2020

What Neural Networks Memorize and Why: Discovering the Long Tail via Influence Estimation

NeurIPS 2020spotlight

Deep learning algorithms are well-known to have a propensity for fitting the training data very well and often fit even outliers and mislabeled data points. Such fitting requires memorization of training data labels, a phenomenon that has attracted significant research interest but has not been give…

Cited by 555SourcePDFScholar
2019

Transfusion: Understanding Transfer Learning for Medical Imaging

NeurIPS 2019poster

Transfer learning from natural image datasets, particularly ImageNet, using standard large models and corresponding pretrained weights has become a de-facto method for deep learning applications to medical imaging. However, there are fundamental differences in data sizes, features and task specific…

Cited by 1515SourcePDFScholar
2018

Machine Theory of Mind

ICML 2018oral

Theory of mind (ToM) broadly refers to humans’ ability to represent the mental states of others, including their desires, beliefs, and intentions. We design a Theory of Mind neural network {–} a ToMnet {–} which uses meta-learning to build such models of the agents it encounters. The ToMnet learns a…

Cited by 732SourcePDFScholar
2017

Understanding deep learning requires rethinking generalization

ICLR 2017oral

Despite their massive size, successful deep artificial neural networks can exhibit a remarkably small difference between training and test performance. Conventional wisdom attributes small generalization error either to properties of the model family, or to the regularization techniques used during…

Cited by 5522SourceScholar
2015

Learning with a Wasserstein Loss

NeurIPS 2015poster

Learning to predict multi-label outputs is challenging, but in many problems there is a natural metric on the outputs that can be used to improve predictions. In this paper we develop a loss function for multi-label learning, based on the Wasserstein distance. The Wasserstein distance provides a nat…

Cited by 773SourcePDFScholar