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Xiaojun Xu

14 accepted papers

2026

Any-Depth Alignment: Unlocking Innate Safety Alignment of LLMs to Any-Depth

ICLR 2026poster

Large Language Models (LLMs) exhibit strong but shallow alignment: they directly refuse harmful queries when a refusal is expected at the very start of an assistant turn, yet this protection collapses once a harmful continuation is underway (either through the adversarial attacks or via harmful assi…

Cited by 0SourceScholar
2025

BRiTE: Bootstrapping Reinforced Thinking Process to Enhance Language Model Reasoning

ICML 2025poster

Large Language Models (LLMs) have demonstrated remarkable capabilities in complex reasoning tasks, yet generating reliable reasoning processes remains a significant challenge. We present a unified probabilistic framework that formalizes LLM reasoning through a novel graphical model incorporating lat…

Cited by 1SourcePDFScholar
2025

Robust Multi-bit Text Watermark with LLM-based Paraphrasers

ICML 2025poster

We propose an imperceptible multi-bit text watermark embedded by paraphrasing with LLMs. We fine-tune a pair of LLM paraphrasers that are designed to behave differently so that their paraphrasing difference reflected in the text semantics can be identified by a trained decoder. To embed our multi-bi…

2025

Toward Optimal LLM Alignments Using Two-Player Games

EMNLP 2025

Alignment of large language models (LLM) is a process that ensures the model’s responses to user prompts align with human intentions and social values. This optimization typically relies on pre-collected prompts. The collection of these prompts often either requires careful human interventions or pr

2024

Effective and Efficient Federated Tree Learning on Hybrid Data

ICLR 2024poster

Federated learning has emerged as a promising distributed learning paradigm that facilitates collaborative learning among multiple parties without transferring raw data. However, most existing federated learning studies focus on either horizontal or vertical data settings, where the data of differen…

Cited by 5SourcePDFScholar
2022

Adversarially Robust Models may not Transfer Better: Sufficient Conditions for Domain Transferability from the View of Regularization

ICML 2022spotlight

Machine learning (ML) robustness and domain generalization are fundamentally correlated: they essentially concern data distribution shifts under adversarial and natural settings, respectively. On one hand, recent studies show that more robust (adversarially trained) models are more generalizable. On…

Cited by 13SourcePDFScholar
2022

On the Certified Robustness for Ensemble Models and Beyond

ICLR 2022poster

Recent studies show that deep neural networks (DNN) are vulnerable to adversarial examples, which aim to mislead DNNs by adding perturbations with small magnitude. To defend against such attacks, both empirical and theoretical defense approaches have been extensively studied for a single ML model. I…

Cited by 60SourcePDFScholar
2021

Nonlinear Projection Based Gradient Estimation for Query Efficient Blackbox Attacks

AISTATS 2021poster

Gradient estimation and vector space projection have been studied as two distinct topics. We aim to bridge the gap between the two by investigating how to efficiently estimate gradient based on a projected low-dimensional space. We first provide lower and upper bounds for gradient estimation under b…

2021

TRS: Transferability Reduced Ensemble via Promoting Gradient Diversity and Model Smoothness

NeurIPS 2021poster

Adversarial Transferability is an intriguing property - adversarial perturbation crafted against one model is also effective against another model, while these models are from different model families or training processes. To better protect ML systems against adversarial attacks, several questions…

Cited by 77SourcePDFScholar
2018

Fooling Vision and Language Models Despite Localization and Attention Mechanism

CVPR 2018poster

Adversarial attacks are known to succeed on classifiers, but it has been an open question whether more complex vision systems are vulnerable. In this paper, we study adversarial examples for vision and language models, which incorporate natural language understanding and complex structures such as a…