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Leheng Sheng

12 accepted papers

2026

AlphaAlign: Incentivizing Safety Alignment with Extremely Simplified Reinforcement Learning

ICLR 2026poster

Large language models (LLMs), despite possessing latent safety understanding from their vast pretraining data, remain vulnerable to generating harmful content and exhibit issues such as over-refusal and utility degradation after safety alignment. Current safety alignment methods often result in supe…

Cited by 0SourceScholar
2026

AlphaSteer: Learning Refusal Steering with Principled Null-Space Constraint

ICLR 2026poster

As LLMs are increasingly deployed in real-world applications, ensuring their ability to refuse malicious prompts, especially jailbreak attacks, is essential for safe and reliable use. Recently, activation steering has emerged as an effective approach for enhancing LLM safety by adding a refusal dire…

Cited by 0SourcecodeScholar
2026

Internalizing Safety Understanding in Large Reasoning Models via Verification

ICML 2026poster

While explicit Chain-of-Thought (CoT) empowers large reasoning models (LRMs), it enables the generation of riskier final answers. Current alignment paradigms primarily rely on externally enforced compliance, optimizing models to detect malicious prompts rather than evaluating the safety of their own…

Cited by 0SourceScholar
2026

Reasoning Can Be Restored by Correcting a Few Decision Tokens

ICML 2026poster

Large reasoning models (LRMs) substantially outperform their base LLM counterparts on challenging reasoning benchmarks, yet it remains poorly understood where base models go wrong during token-by-token generation and how to narrow this gap efficiently. We study the base–reasoning gap by quantifying …

Cited by 0SourceScholar
2026

When to Memorize and When to Stop: Gated Recurrent Memory for Long-Context Reasoning

ICML 2026poster

While reasoning over long context is crucial for various real-world applications, it remains challenging for large language models (LLMs) as they suffer from performance degradation as the context length grows. Recent work MemAgent has tried to tackle this by processing context chunk-by-chunk in an …

Cited by 0SourceScholar
2025

AgentRecBench: Benchmarking LLM Agent-based Personalized Recommender Systems

NeurIPS 2025spotlight

The emergence of agentic recommender systems powered by Large Language Models (LLMs) represents a paradigm shift in personalized recommendations, leveraging LLMs’ advanced reasoning and role-playing capabilities to enable autonomous, adaptive decision-making. Unlike traditional recommendation approa…

Cited by 0SourcecodeScholar
2025

Language Representations Can be What Recommenders Need: Findings and Potentials

ICLR 2025oral

Recent studies empirically indicate that language models (LMs) encode rich world knowledge beyond mere semantics, attracting significant attention across various fields. However, in the recommendation domain, it remains uncertain whether LMs implicitly encode user preference information. Contrary to…

2025

On Reasoning Strength Planning in Large Reasoning Models

NeurIPS 2025poster

Recent studies empirically reveal that large reasoning models (LRMs) can automatically allocate more reasoning strengths (\ie the number of reasoning tokens) for harder problems, exhibiting difficulty-awareness for better task performance. While this automatic reasoning strength allocation phenomeno…

Cited by 0SourcecodeScholar
2024

Customizing Language Models with Instance-wise LoRA for Sequential Recommendation

NeurIPS 2024poster

Sequential recommendation systems predict the next interaction item based on users' past interactions, aligning recommendations with individual preferences. Leveraging the strengths of Large Language Models (LLMs) in knowledge comprehension and reasoning, recent approaches are eager to apply LLMs t…

2024

On Softmax Direct Preference Optimization for Recommendation

NeurIPS 2024poster

Recommender systems aim to predict personalized rankings based on user preference data. With the rise of Language Models (LMs), LM-based recommenders have been widely explored due to their extensive world knowledge and powerful reasoning abilities. Most of the LM-based recommenders convert historica…

2023

Brainnetformer: Decoding Brain Cognitive States with Spatial-Temporal Cross Attention

ICASSP 2023accepted

Learning about the cognitive state of the brain has always been a popular topic. Based on the fact that fluctuations of brain signals and functional connectome (FC) relate to specific human behaviors, deep learning based methods have shown promising results on the prediction of such behaviors by ana…

Cited by 0SourceScholar
2023

Empowering Collaborative Filtering with Principled Adversarial Contrastive Loss

NeurIPS 2023poster

Contrastive Learning (CL) has achieved impressive performance in self-supervised learning tasks, showing superior generalization ability. Inspired by the success, adopting CL into collaborative filtering (CF) is prevailing in semi-supervised topK recommendations. The basic idea is to routinely condu…