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Cen Chen

43 accepted papers

2026

ARGUS: Defending Against Multimodal Indirect Prompt Injection via Steering Instruction-Following Behavior

CVPR 2026

Multimodal Large Language Models (MLLMs) are increasingly vulnerable to multimodal Indirect Prompt Injection (IPI) attacks, which embed malicious instructions in images, videos, or audio to hijack model behavior. Existing defenses, designed primarily for text-only LLMs, are unsuitable for countering

Cited by 0SourcecodeScholar
2026

Are Global Dependencies Necessary? Scalable Time Series Forecasting via Local Cross-Variate Modeling

ICLR 2026poster

Effectively modeling cross-variate dependencies is a central, yet challenging, task in multivariate time series forecasting. While attention-based methods have advanced the state-of-the-art by capturing global cross-variate dependencies, their quadratic complexity with respect to the number of varia…

Cited by 0SourceScholar
2026

AttriCtrl: A Generalizable Framework for Controlling Semantic Attribute Intensity in Diffusion Models

ICLR 2026poster

Diffusion models have recently become the dominant paradigm for image generation, yet existing systems struggle to interpret and follow numeric instructions for adjusting semantic attributes. In real-world creative scenarios, especially when precise control over aesthetic attributes is required, cu…

Cited by 0SourceScholar
2026

FILTER: A Framework for Defending Against Backdoor Attacks in Vertical Federated Learning

AAAI 2026technical

Vertical Federated Learning (VFL) is a distributed machine learning paradigm in which participants train models with vertically partitioned data. Many previous studies have identified backdoor vulnerabilities in VFL systems. However, limited effort has been devoted to developing defenses against suc

Cited by 0SourcePDFScholar
2026

NDAD: Negative-Direction Aware Decoding for Large Language Models via Controllable Hallucination Signal Injection

ICLR 2026poster

Large language models (LLMs) have recently achieved impressive progress in knowledge-intensive and reasoning tasks. However, their tendency to produce fabricated or factually inconsistent content remains a fundamental challenge to their practical deployment. To address this issue, we propose Negativ…

Cited by 0SourceScholar
2026

PlugGuard: A Streaming Safeguard for Large Models via Latent Dynamics-Guided Risk Detection

ICML 2026poster

Large models (LMs) are powerful content generators, yet their open‑ended nature can also introduce potential risks, such as generating harmful or biased content. Existing guardrails mostly perform post-hoc detection that may expose unsafe content before it is caught, and the latency constraints furt…

Cited by 0SourceScholar
2026

RCP-Merging: Merging Long Chain-of-Thought Models with Domain-Specific Models by Considering Reasoning Capability as Prior

AAAI 2026technical

Large Language Models (LLMs) with long chain-of-thought (CoT) capability, termed Reasoning Models, demonstrate superior intricate problem-solving abilities through multi-step long CoT reasoning. To create a dual-capability model with long CoT capability and domain-specific knowledge without substant

Cited by 0SourcePDFScholar
2026

Spectral Evolution Search: Efficient Inference-Time Scaling for Reward-Aligned Image Generation

ICML 2026poster

Inference-time scaling offers a versatile paradigm for aligning visual generative models with downstream objectives without parameter updates. However, existing approaches that optimize the high-dimensional initial noise suffer from severe inefficiency, as many search directions exert negligible inf…

Cited by 0SourceScholar
2025

Bad-PFL: Exploiting Backdoor Attacks against Personalized Federated Learning

ICLR 2025poster

Data heterogeneity and backdoor attacks rank among the most significant challenges facing federated learning (FL). For data heterogeneity, personalized federated learning (PFL) enables each client to maintain a private personalized model to cater to client-specific knowledge. Meanwhile, vanilla FL h…

Cited by 1SourcePDFScholar
2025

Comprehensive Assessment and Analysis for NSFW Content Erasure in Text-to-Image Diffusion models

NeurIPS 2025poster

Text-to-image diffusion models have gained widespread application across various domains, demonstrating remarkable creative potential. However, the strong generalization capabilities of diffusion models can inadvertently lead to the generation of not-safe-for-work (NSFW) content, posing significant…

Cited by 0SourceScholar
2025

Enhancing Portfolio Optimization via Heuristic-Guided Inverse Reinforcement Learning with Multi-Objective Reward and Graph-based Policy Learning

IJCAI 2025

Portfolio optimization encounters persistent challenges in adapting to dynamic markets due to static assumptions and high-dimensional decision spaces. Although reinforcement learning (RL) has emerged as a potential solution, conventional reward engineering often fails to capture complex market dynam

2025

ExVideo: Extending Video Diffusion Models via Parameter-Efficient Post-Tuning

IJCAI 2025

Recently, advancements in video synthesis have attracted significant attention. Video synthesis models have demonstrated the practical applicability of diffusion models in creating dynamic visual content. Despite these advancements, the extension of video lengths remains constrained by computational

2025

FastBlend: Enhancing Video Stylization Consistency via Model-Free Patch Blending

IJCAI 2025

With the emergence of diffusion models and the rapid development of image processing, generating artistic images in style transfer tasks has become effortless. However, these impressive image processing approaches face consistency issues in video processing due to the independent processing of each

2025

GSDNet: Revisiting Incomplete Multimodality-Diffusion Emotion Recognition from the Perspective of Graph Spectrum

IJCAI 2025

Multimodal Emotion Recognition (MER) combines technologies from multiple fields (e.g., computer vision, natural language processing, and audio signal processing), aiming to infer an individual's emotional state by analyzing information from different sources (i.e., video, audio, and text). Compared

Cited by 0SourcePDFScholar
2025

GenderAlign: An Alignment Dataset for Mitigating Gender Bias in Large Language Models

ACL 2025long

Large Language Models (LLMs) are prone to generating content that exhibits gender biases, raising significant ethical concerns. Alignment, the process of fine-tuning LLMs to better align with desired behaviors, is recognized as an effective approach to mitigate gender biases. Although proprietary LL…

2025

Growth Inhibitors for Suppressing Inappropriate Image Concepts in Diffusion Models

ICLR 2025poster

Despite their remarkable image generation capabilities, text-to-image diffusion models inadvertently learn inappropriate concepts from vast and unfiltered training data, which leads to various ethical and business risks. Specifically, model-generated images may exhibit not safe for work (NSFW) conte…

Cited by 2SourcePDFScholar
2025

L3A: Label-Augmented Analytic Adaptation for Multi-Label Class Incremental Learning

ICML 2025poster

Class-incremental learning (CIL) enables models to learn new classes continually without forgetting previously acquired knowledge. Multi-label CIL (MLCIL) extends CIL to a real-world scenario where each sample may belong to multiple classes, introducing several challenges: label absence, which leads…

2025

LSSF: Safety Alignment for Large Language Models through Low-Rank Safety Subspace Fusion

ACL 2025long

The safety mechanisms of large language models (LLMs) exhibit notable fragility, as even fine-tuning on datasets without harmful content may still undermine their safety capabilities. Meanwhile, existing safety alignment methods predominantly rely on the fine-tuning process, which inadvertently lead…

2025

PrivacyRestore: Privacy-Preserving Inference in Large Language Models via Privacy Removal and Restoration

ACL 2025long

The widespread usage of online Large Language Models (LLMs) inference services has raised significant privacy concerns about the potential exposure of private information in user inputs. Existing privacy protection methods for LLMs suffer from either insufficient privacy protection with performance…

Cited by 0SourcePDFScholar
2025

RewardDS: Privacy-Preserving Fine-Tuning for Large Language Models via Reward Driven Data Synthesis

EMNLP 2025

The success of large language models (LLMs) has attracted many individuals to fine-tune them for domain-specific tasks by uploading their data. However, in sensitive areas like healthcare and finance, privacy concerns often arise. One promising solution is to generate synthetic data with Differentia

2025

SEA: Low-Resource Safety Alignment for Multimodal Large Language Models via Synthetic Embeddings

ACL 2025long

Multimodal Large Language Models (MLLMs) have serious security vulnerabilities. While safety alignment using multimodal datasets consisting of text and data of additional modalities can effectively enhance MLLM’s security, it is costly to construct these datasets. Existing low-resource security alig…

2025

Semantic Shift Estimation via Dual-Projection and Classifier Reconstruction for Exemplar-Free Class-Incremental Learning

ICML 2025poster

Exemplar-Free Class-Incremental Learning (EFCIL) aims to sequentially learn from distinct categories without retaining exemplars but easily suffers from catastrophic forgetting of learned knowledge. While existing EFCIL methods leverage knowledge distillation to alleviate forgetting, they still face…

2025

TOTF: Missing-Aware Encoders for Clustering on Multi-View Incomplete Attributed Graphs

IJCAI 2025

As the network data in real life become multi-modal and multi-relational, multi-view attributed graphs have garnered significant attention. Numerous methods have achieved excellent performance in multi-view attributed graph clustering; however, they cannot efficiently handle incomplete attribute sce

Cited by 0SourcePDFScholar
2024

Approximate Kernel Density Estimation under Metric-based Local Differential Privacy

UAI 2024poster

Kernel Density Estimation (KDE) is a fundamental problem with broad machine learning applications. In this paper, we investigate the KDE problem under Local Differential Privacy (LDP), a setting in which users privatize data on their own devices before sending them to an untrusted server for analyti…

Cited by 0SourcePDFScholar
2024

ConsistentEE: A Consistent and Hardness-Guided Early Exiting Method for Accelerating Language Models Inference

AAAI 2024technical

Early Exiting is one of the most popular methods to achieve efficient inference. Current early exiting methods adopt the (weighted) sum of the cross entropy loss of all internal classifiers as the objective function during training, imposing all these classifiers to predict all instances correctly.…

2024

DS-AL: A Dual-Stream Analytic Learning for Exemplar-Free Class-Incremental Learning

AAAI 2024technical

Class-incremental learning (CIL) under an exemplar-free constraint has presented a significant challenge. Existing methods adhering to this constraint are prone to catastrophic forgetting, far more so than replay-based techniques that retain access to past samples. In this paper, to solve the exem…

2024

Diffutoon: High-Resolution Editable Toon Shading via Diffusion Models

IJCAI 2024poster

Toon shading is a type of non-photorealistic rendering task in animation. Its primary purpose is to render objects with a flat and stylized appearance. As diffusion models have ascended to the forefront of image synthesis, this paper delves into an innovative form of toon shading based on diffusion…

2024

F-OAL: Forward-only Online Analytic Learning with Fast Training and Low Memory Footprint in Class Incremental Learning

NeurIPS 2024poster

Online Class Incremental Learning (OCIL) aims to train models incrementally, where data arrive in mini-batches, and previous data are not accessible. A major challenge in OCIL is Catastrophic Forgetting, i.e., the loss of previously learned knowledge. Among existing baselines, replay-based methods s…

2024

GACL: Exemplar-Free Generalized Analytic Continual Learning

NeurIPS 2024poster

Class incremental learning (CIL) trains a network on sequential tasks with separated categories in each task but suffers from catastrophic forgetting, where models quickly lose previously learned knowledge when acquiring new tasks. The generalized CIL (GCIL) aims to address the CIL problem in a more…

2024

PAI-Diffusion: Constructing and Serving a Family of Open Chinese Diffusion Models for Text-to-image Synthesis on the Cloud

ACL 2024system demonstrations

Text-to-image synthesis for the Chinese language poses unique challenges due to its large vocabulary size, and intricate character relationships. While existing diffusion models have shown promise in generating images from textual descriptions, they often neglect domain-specific contexts and lack ro…

2024

TaiChi: Improving the Robustness of NLP Models by Seeking Common Ground While Reserving Differences

COLING 2024main

Recent studies have shown that Pre-trained Language Models (PLMs) are vulnerable to adversarial examples, crafted by introducing human-imperceptible perturbations to clean examples to deceive the models. This vulnerability stems from the divergence in the data distributions of clean and adversarial…

2024

Transferability Bound Theory: Exploring Relationship between Adversarial Transferability and Flatness

NeurIPS 2024poster

A prevailing belief in attack and defense community is that the higher flatness of adversarial examples enables their better cross-model transferability, leading to a growing interest in employing sharpness-aware minimization and its variants. However, the theoretical relationship between the transf…

2023

A Customized Text Sanitization Mechanism with Differential Privacy

ACL 2023findings

As privacy issues are receiving increasing attention within the Natural Language Processing (NLP) community, numerous methods have been proposed to sanitize texts subject to differential privacy. However, the state-of-the-art text sanitization mechanisms based on a relaxed notion of metric local dif…

2023

CPCM: Contextual Point Cloud Modeling for Weakly-supervised Point Cloud Semantic Segmentation

ICCV 2023poster

We study the task of weakly-supervised point cloud semantic segmentation with sparse annotations (e.g., less than 0.1% points are labeled), aiming to reduce the expensive cost of dense annotations. Unfortunately, with extremely sparse annotated points, it is very difficult to extract both contextual…

Cited by 32PDFcodeScholar
2023

DocAsRef: An Empirical Study on Repurposing Reference-based Summary Quality Metrics as Reference-free Metrics

EMNLP 2023short findings

Automated summary quality assessment falls into two categories: reference-based and reference-free. Reference-based metrics, historically deemed more accurate due to the additional information provided by human-written references, are limited by their reliance on human input. In this paper, we hypot…

Cited by 0SourceScholar
2023

Learning Knowledge-Enhanced Contextual Language Representations for Domain Natural Language Understanding

EMNLP 2023long main

Knowledge-Enhanced Pre-trained Language Models (KEPLMs) improve the performance of various downstream NLP tasks by injecting knowledge facts from large-scale Knowledge Graphs (KGs). However, existing methods for pre-training KEPLMs with relational triples are difficult to be adapted to close domains…

Cited by 0SourceScholar
2023

Rapid Diffusion: Building Domain-Specific Text-to-Image Synthesizers with Fast Inference Speed

ACL 2023industry

Text-to-Image Synthesis (TIS) aims to generate images based on textual inputs. Recently, several large pre-trained diffusion models have been released to create high-quality images with pre-trained text encoders and diffusion-based image synthesizers. However, popular diffusion-based models from the…

2023

XtremeCLIP: Extremely Parameter-efficient Tuning for Low-resource Vision Language Understanding

ACL 2023findings

Recently, Contrastive Visual-Language Pre-training (CLIP) has demonstrated remarkable capability in various Visual Language Understanding (VLU) tasks. Yet, most CLIP-based methods require tasks-specific designs and sufficient training data. In this paper, we introduce a simple yet efficient paradigm…

2022

Combating False Sense of Security: Breaking the Defense of Adversarial Training Via Non-Gradient Adversarial Attack

ICASSP 2022accepted

Adversarial training is believed to be the most robust and effective defense method against adversarial attacks. Gradient-based adversarial attack methods are generally adopted to evaluate the effectiveness of adversarial training. However, in this paper, by diving into the existing adversarial atta…

Cited by 0SourceScholar
2022

SueNes: A Weakly Supervised Approach to Evaluating Single-Document Summarization via Negative Sampling

NAACL 2022long

Canonical automatic summary evaluation metrics, such as ROUGE, focus on lexical similarity which cannot well capture semantics nor linguistic quality and require a reference summary which is costly to obtain. Recently, there have been a growing number of efforts to alleviate either or both of the tw…

2021

Privacy-Preserving Optimal Insulin Dosing Decision

ICASSP 2021accepted

Precision diagnosis and treatment are blending outcomes of machine learning and the Internet of Medical Things (IoMT). In the diabetes treatment, a medical center acts as a medical service provider (MSP) with patients data from IoMT devices. The MSP calculates the accurate dosage by importing the he…

Cited by 0SourceScholar
2021

Reinforced History Backtracking for Conversational Question Answering

AAAI 2021technical

To model the context history in multi-turn conversations has become a critical step towards a better understanding of the user query in question answering systems. To utilize the context history, most existing studies treat the whole context as input, which will inevitably face the following two cha…