Search Results for author: Linjun Zhang

Found 59 papers, 19 papers with code

A Theoretical Framework for Prompt Engineering: Approximating Smooth Functions with Transformer Prompts

no code implementations26 Mar 2025 Ryumei Nakada, Wenlong Ji, Tianxi Cai, James Zou, Linjun Zhang

Prompt engineering has emerged as a powerful technique for guiding large language models (LLMs) toward desired responses, significantly enhancing their performance across diverse tasks.

AI Agent Prompt Engineering

An Overview of Large Language Models for Statisticians

no code implementations25 Feb 2025 Wenlong Ji, Weizhe Yuan, Emily Getzen, Kyunghyun Cho, Michael I. Jordan, Song Mei, Jason E Weston, Weijie J. Su, Jing Xu, Linjun Zhang

Large Language Models (LLMs) have emerged as transformative tools in artificial intelligence (AI), exhibiting remarkable capabilities across diverse tasks such as text generation, reasoning, and decision-making.

Causal Inference Decision Making +3

RoseRAG: Robust Retrieval-augmented Generation with Small-scale LLMs via Margin-aware Preference Optimization

no code implementations16 Feb 2025 Tianci Liu, Haoxiang Jiang, Tianze Wang, ran Xu, Yue Yu, Linjun Zhang, Tuo Zhao, Haoyu Wang

Large language models (LLMs) have achieved impressive performance but face high computational costs and latency, limiting their deployment in resource-constrained settings.

Open-Domain Question Answering RAG +2

A Statistical Hypothesis Testing Framework for Data Misappropriation Detection in Large Language Models

no code implementations5 Jan 2025 Yinpeng Cai, Lexin Li, Linjun Zhang

To address this issue, we propose embedding watermarks into the copyrighted training data and formulating the detection of data misappropriation as a hypothesis testing problem.

S$^{2}$FT: Efficient, Scalable and Generalizable LLM Fine-tuning by Structured Sparsity

no code implementations9 Dec 2024 Xinyu Yang, Jixuan Leng, Geyang Guo, Jiawei Zhao, Ryumei Nakada, Linjun Zhang, Huaxiu Yao, Beidi Chen

Utilizing this key insight, we propose a family of Structured Sparse Fine-Tuning (S$^{2}$FT) methods for LLMs, which concurrently achieve state-of-the-art fine-tuning performance, training efficiency, and inference scalability.

Arithmetic Reasoning

Differentially Private Learning Beyond the Classical Dimensionality Regime

no code implementations20 Nov 2024 Cynthia Dwork, Pranay Tankala, Linjun Zhang

We provide sharp theoretical estimates of the error of several well-studied differentially private algorithms for robust linear regression and logistic regression, including output perturbation, objective perturbation, and noisy stochastic gradient descent, in the proportional dimensionality regime.

regression

FactTest: Factuality Testing in Large Language Models with Finite-Sample and Distribution-Free Guarantees

no code implementations4 Nov 2024 Fan Nie, Xiaotian Hou, Shuhang Lin, James Zou, Huaxiu Yao, Linjun Zhang

The propensity of Large Language Models (LLMs) to generate hallucinations and non-factual content undermines their reliability in high-stakes domains, where rigorous control over Type I errors (the conditional probability of incorrectly classifying hallucinations as truthful content) is essential.

Multiple-choice Question Answering

MMed-RAG: Versatile Multimodal RAG System for Medical Vision Language Models

1 code implementation16 Oct 2024 Peng Xia, Kangyu Zhu, Haoran Li, Tianze Wang, Weijia Shi, Sheng Wang, Linjun Zhang, James Zou, Huaxiu Yao

Artificial Intelligence (AI) has demonstrated significant potential in healthcare, particularly in disease diagnosis and treatment planning.

Diagnostic Hallucination +3

NEAT: Nonlinear Parameter-efficient Adaptation of Pre-trained Models

no code implementations2 Oct 2024 Yibo Zhong, Haoxiang Jiang, Lincan Li, Ryumei Nakada, Tianci Liu, Linjun Zhang, Huaxiu Yao, Haoyu Wang

The nonlinear approximation directly models the cumulative updates, effectively capturing complex and non-linear structures in the weight updates.

parameter-efficient fine-tuning

RULE: Reliable Multimodal RAG for Factuality in Medical Vision Language Models

1 code implementation6 Jul 2024 Peng Xia, Kangyu Zhu, Haoran Li, Hongtu Zhu, Yun Li, Gang Li, Linjun Zhang, Huaxiu Yao

Second, in cases where the model originally responds correctly, applying RAG can lead to an over-reliance on retrieved contexts, resulting in incorrect answers.

Medical Diagnosis RAG +2

F-FOMAML: GNN-Enhanced Meta-Learning for Peak Period Demand Forecasting with Proxy Data

no code implementations23 Jun 2024 Zexing Xu, Linjun Zhang, Sitan Yang, Rasoul Etesami, Hanghang Tong, huan zhang, Jiawei Han

In this paper, we propose a novel approach that leverages strategically chosen proxy data reflective of potential sales patterns from similar entities during non-peak periods, enriched by features learned from a graph neural networks (GNNs)-based forecasting model, to predict demand during peak events.

Demand Forecasting Meta-Learning

Synthetic Oversampling: Theory and A Practical Approach Using LLMs to Address Data Imbalance

1 code implementation5 Jun 2024 Ryumei Nakada, Yichen Xu, Lexin Li, Linjun Zhang

In the context of imbalanced data, LLMs are used to oversample underrepresented groups and have shown promising improvements.

Data Augmentation imbalanced classification +1

Order-Independence Without Fine Tuning

1 code implementation4 Jun 2024 Reid McIlroy-Young, Katrina Brown, Conlan Olson, Linjun Zhang, Cynthia Dwork

One problematic inconsistency when LLMs are used to answer multiple-choice questions or analyze multiple inputs is order dependency: the output of an LLM can (and often does) change significantly when sub-sequences are swapped, despite both orderings being semantically identical.

Language Modelling Multiple-choice +1

Calibrated Self-Rewarding Vision Language Models

1 code implementation23 May 2024 Yiyang Zhou, Zhiyuan Fan, Dongjie Cheng, Sihan Yang, Zhaorun Chen, Chenhang Cui, Xiyao Wang, Yun Li, Linjun Zhang, Huaxiu Yao

In the reward modeling, we employ a step-wise strategy and incorporate visual constraints into the self-rewarding process to place greater emphasis on visual input.

Hallucination Language Modelling +1

Fair Risk Control: A Generalized Framework for Calibrating Multi-group Fairness Risks

no code implementations3 May 2024 Lujing Zhang, Aaron Roth, Linjun Zhang

This paper introduces a framework for post-processing machine learning models so that their predictions satisfy multi-group fairness guarantees.

Fairness Image Segmentation +3

A Unified Combination Framework for Dependent Tests with Applications to Microbiome Association Studies

no code implementations14 Apr 2024 Xiufan Yu, Linjun Zhang, Arun Srinivasan, Min-ge Xie, Lingzhou Xue

Compared to the existing $p$-value combination methods, including the vanilla Cauchy combination method, the proposed combination framework can handle the dependence accurately and utilizes the information efficiently to construct tests with accurate size and enhanced power.

Contrastive Learning on Multimodal Analysis of Electronic Health Records

no code implementations22 Mar 2024 Tianxi Cai, Feiqing Huang, Ryumei Nakada, Linjun Zhang, Doudou Zhou

To accommodate the statistical analysis of multimodal EHR data, in this paper, we propose a novel multimodal feature embedding generative model and design a multimodal contrastive loss to obtain the multimodal EHR feature representation.

Contrastive Learning Privacy Preserving +1

Provable Multi-Party Reinforcement Learning with Diverse Human Feedback

no code implementations8 Mar 2024 Huiying Zhong, Zhun Deng, Weijie J. Su, Zhiwei Steven Wu, Linjun Zhang

Our work \textit{initiates} the theoretical study of multi-party RLHF that explicitly models the diverse preferences of multiple individuals.

Fairness Meta-Learning +2

Distribution-Free Fair Federated Learning with Small Samples

no code implementations25 Feb 2024 Qichuan Yin, Zexian Wang, Junzhou Huang, Huaxiu Yao, Linjun Zhang

As federated learning gains increasing importance in real-world applications due to its capacity for decentralized data training, addressing fairness concerns across demographic groups becomes critically important.

Fairness Federated Learning

Selective Learning: Towards Robust Calibration with Dynamic Regularization

no code implementations13 Feb 2024 Zongbo Han, Yifeng Yang, Changqing Zhang, Linjun Zhang, Joey Tianyi Zhou, QinGhua Hu

The objective can be understood as seeking a model that fits the ground-truth labels by increasing the confidence while also maximizing the entropy of predicted probabilities by decreasing the confidence.

Differentially Private Sliced Inverse Regression: Minimax Optimality and Algorithm

no code implementations16 Jan 2024 Xintao Xia, Linjun Zhang, Zhanrui Cai

Privacy preservation has become a critical concern in high-dimensional data analysis due to the growing prevalence of data-driven applications.

Dimensionality Reduction regression

Can AI Be as Creative as Humans?

no code implementations3 Jan 2024 Haonan Wang, James Zou, Michael Mozer, Anirudh Goyal, Alex Lamb, Linjun Zhang, Weijie J Su, Zhun Deng, Michael Qizhe Xie, Hannah Brown, Kenji Kawaguchi

With the rise of advanced generative AI models capable of tasks once reserved for human creativity, the study of AI's creative potential becomes imperative for its responsible development and application.

Holistic Analysis of Hallucination in GPT-4V(ision): Bias and Interference Challenges

1 code implementation6 Nov 2023 Chenhang Cui, Yiyang Zhou, Xinyu Yang, Shirley Wu, Linjun Zhang, James Zou, Huaxiu Yao

To bridge this gap, we introduce a new benchmark, namely, the Bias and Interference Challenges in Visual Language Models (Bingo).

Hallucination

Conformal Prediction for Deep Classifier via Label Ranking

3 code implementations10 Oct 2023 Jianguo Huang, Huajun Xi, Linjun Zhang, Huaxiu Yao, Yue Qiu, Hongxin Wei

Conformal prediction is a statistical framework that generates prediction sets containing ground-truth labels with a desired coverage guarantee.

Conformal Prediction Prediction

Multi-dimensional domain generalization with low-rank structures

1 code implementation18 Sep 2023 Sai Li, Linjun Zhang

In conventional statistical and machine learning methods, it is typically assumed that the test data are identically distributed with the training data.

Domain Generalization

What Should Data Science Education Do with Large Language Models?

no code implementations6 Jul 2023 Xinming Tu, James Zou, Weijie J. Su, Linjun Zhang

LLMs can also play a significant role in the classroom as interactive teaching and learning tools, contributing to personalized education.

Discover and Cure: Concept-aware Mitigation of Spurious Correlation

1 code implementation1 May 2023 Shirley Wu, Mert Yuksekgonul, Linjun Zhang, James Zou

Deep neural networks often rely on spurious correlations to make predictions, which hinders generalization beyond training environments.

Lesion Classification Object Recognition +1

Score Attack: A Lower Bound Technique for Optimal Differentially Private Learning

no code implementations13 Mar 2023 T. Tony Cai, Yichen Wang, Linjun Zhang

The score attack method is based on the tracing attack concept in differential privacy and can be applied to any statistical model with a well-defined score statistic.

parameter estimation

HappyMap: A Generalized Multi-calibration Method

no code implementations8 Mar 2023 Zhun Deng, Cynthia Dwork, Linjun Zhang

Fairness is captured by incorporating demographic subgroups into the class of functions~$\mathcal{C}$.

Conformal Prediction Fairness +1

Understanding Multimodal Contrastive Learning and Incorporating Unpaired Data

1 code implementation13 Feb 2023 Ryumei Nakada, Halil Ibrahim Gulluk, Zhun Deng, Wenlong Ji, James Zou, Linjun Zhang

We show that the algorithm can detect the ground-truth pairs and improve performance by fully exploiting unpaired datasets.

Contrastive Learning

Reinforcement Learning with Stepwise Fairness Constraints

no code implementations8 Nov 2022 Zhun Deng, He Sun, Zhiwei Steven Wu, Linjun Zhang, David C. Parkes

AI methods are used in societally important settings, ranging from credit to employment to housing, and it is crucial to provide fairness in regard to algorithmic decision making.

Decision Making Fairness +3

Freeze then Train: Towards Provable Representation Learning under Spurious Correlations and Feature Noise

1 code implementation20 Oct 2022 Haotian Ye, James Zou, Linjun Zhang

This opens a promising strategy to first train a feature learner rather than a classifier, and then perform linear probing (last layer retraining) in the test environment.

Representation Learning

C-Mixup: Improving Generalization in Regression

1 code implementation11 Oct 2022 Huaxiu Yao, Yiping Wang, Linjun Zhang, James Zou, Chelsea Finn

In this paper, we propose a simple yet powerful algorithm, C-Mixup, to improve generalization on regression tasks.

regression

FIFA: Making Fairness More Generalizable in Classifiers Trained on Imbalanced Data

no code implementations6 Jun 2022 Zhun Deng, Jiayao Zhang, Linjun Zhang, Ting Ye, Yates Coley, Weijie J. Su, James Zou

Specifically, FIFA encourages both classification and fairness generalization and can be flexibly combined with many existing fair learning methods with logits-based losses.

Classification Fairness

Improving Out-of-Distribution Robustness via Selective Augmentation

3 code implementations2 Jan 2022 Huaxiu Yao, Yu Wang, Sai Li, Linjun Zhang, Weixin Liang, James Zou, Chelsea Finn

Machine learning algorithms typically assume that training and test examples are drawn from the same distribution.

Scaffolding Sets

no code implementations4 Nov 2021 Maya Burhanpurkar, Zhun Deng, Cynthia Dwork, Linjun Zhang

Predictors map individual instances in a population to the interval $[0, 1]$.

The Power of Contrast for Feature Learning: A Theoretical Analysis

no code implementations6 Oct 2021 Wenlong Ji, Zhun Deng, Ryumei Nakada, James Zou, Linjun Zhang

Contrastive learning has achieved state-of-the-art performance in various self-supervised learning tasks and even outperforms its supervised counterpart.

Contrastive Learning Self-Supervised Learning +1

Understanding Dynamics of Nonlinear Representation Learning and Its Application

no code implementations28 Jun 2021 Kenji Kawaguchi, Linjun Zhang, Zhun Deng

Representation learning allows us to automatically discover suitable representations from raw sensory data.

Representation Learning

Adversarial Training Helps Transfer Learning via Better Representations

no code implementations NeurIPS 2021 Zhun Deng, Linjun Zhang, Kailas Vodrahalli, Kenji Kawaguchi, James Zou

Recent works empirically demonstrate that adversarial training in the source data can improve the ability of models to transfer to new domains.

Transfer Learning

Meta-Learning with Fewer Tasks through Task Interpolation

1 code implementation ICLR 2022 Huaxiu Yao, Linjun Zhang, Chelsea Finn

Meta-learning enables algorithms to quickly learn a newly encountered task with just a few labeled examples by transferring previously learned knowledge.

Image Classification Medical Image Classification +3

High-Dimensional Differentially-Private EM Algorithm: Methods and Near-Optimal Statistical Guarantees

no code implementations1 Apr 2021 Zhe Zhang, Linjun Zhang

In this paper, we develop a general framework to design differentially private expectation-maximization (EM) algorithms in high-dimensional latent variable models, based on the noisy iterative hard-thresholding.

regression

A Central Limit Theorem for Differentially Private Query Answering

no code implementations NeurIPS 2021 Jinshuo Dong, Weijie J. Su, Linjun Zhang

The central question, therefore, is to understand which noise distribution optimizes the privacy-accuracy trade-off, especially when the dimension of the answer vector is high.

When and How Mixup Improves Calibration

no code implementations11 Feb 2021 Linjun Zhang, Zhun Deng, Kenji Kawaguchi, James Zou

In addition, we study how Mixup improves calibration in semi-supervised learning.

Data Augmentation

The Cost of Privacy in Generalized Linear Models: Algorithms and Minimax Lower Bounds

no code implementations8 Nov 2020 T. Tony Cai, Yichen Wang, Linjun Zhang

We propose differentially private algorithms for parameter estimation in both low-dimensional and high-dimensional sparse generalized linear models (GLMs) by constructing private versions of projected gradient descent.

LEMMA parameter estimation

Estimation, Confidence Intervals, and Large-Scale Hypotheses Testing for High-Dimensional Mixed Linear Regression

no code implementations6 Nov 2020 Linjun Zhang, Rong Ma, T. Tony Cai, Hongzhe Li

Based on the iterative estimators, we further construct debiased estimators and establish their asymptotic normality.

regression

How Does Mixup Help With Robustness and Generalization?

no code implementations ICLR 2021 Linjun Zhang, Zhun Deng, Kenji Kawaguchi, Amirata Ghorbani, James Zou

For robustness, we show that minimizing the Mixup loss corresponds to approximately minimizing an upper bound of the adversarial loss.

Data Augmentation

Interpreting Robust Optimization via Adversarial Influence Functions

no code implementations ICML 2020 Zhun Deng, Cynthia Dwork, Jialiang Wang, Linjun Zhang

Robust optimization has been widely used in nowadays data science, especially in adversarial training.

A Lightweight Algorithm to Uncover Deep Relationships in Data Tables

no code implementations7 Sep 2020 Jin Cao, Yibo Zhao, Linjun Zhang, Jason Li

The key to our approach is a computationally lightweight forward addition algorithm that we developed to recursively extract the functional dependencies between table columns that are scalable to tables with many columns.

Improving Generalization in Meta-learning via Task Augmentation

1 code implementation26 Jul 2020 Huaxiu Yao, Long-Kai Huang, Linjun Zhang, Ying WEI, Li Tian, James Zou, Junzhou Huang, Zhenhui Li

Moreover, both MetaMix and Channel Shuffle outperform state-of-the-art results by a large margin across many datasets and are compatible with existing meta-learning algorithms.

Meta-Learning

Improving Adversarial Robustness via Unlabeled Out-of-Domain Data

no code implementations15 Jun 2020 Zhun Deng, Linjun Zhang, Amirata Ghorbani, James Zou

In this work, we investigate how adversarial robustness can be enhanced by leveraging out-of-domain unlabeled data.

Adversarial Robustness Data Augmentation +2

The Cost of Privacy: Optimal Rates of Convergence for Parameter Estimation with Differential Privacy

no code implementations12 Feb 2019 T. Tony Cai, Yichen Wang, Linjun Zhang

By refining the "tracing adversary" technique for lower bounds in the theoretical computer science literature, we formulate a general lower bound argument for minimax risks with differential privacy constraints, and apply this argument to high-dimensional mean estimation and linear regression problems.

parameter estimation Privacy Preserving +1

A Sparse PCA Approach to Clustering

no code implementations16 Feb 2016 T. Tony Cai, Linjun Zhang

We discuss a clustering method for Gaussian mixture model based on the sparse principal component analysis (SPCA) method and compare it with the IF-PCA method.

Clustering

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