Publications

See an updated list of publications in my Google scholar page. But here you can find a categorized list of them.

Alignment

• SEAL: Safety-enhanced Aligned LLM Fine-tuning via Bilevel Data Selection
  Han Shen, Pin-Yu Chen, Payel Das, Tianyi Chen
  ICLR 2025. [arxiv]

• Fundamental Safety-Capability Trade-offs in Fine-tuning Large Language Models
  Pin-Yu Chen*, Han Shen*, Payel Das, Tianyi Chen
  *equal contribution, preprint. [arxiv]

• Mitigating Forgetting in LLM Supervised Fine-Tuning and Preference Learning
  Heshan Fernando*, Han Shen*, Parikshit Ram, Yi Zhou, Horst Samulowitz, Nathalie Baracaldo, Tianyi Chen
  *equal contribution, preprint. [arxiv]

Optimization

• On Penalty-based Bilevel Gradient Descent Method
  Han Shen, Quan Xiao, Tianyi Chen
  ICML 2023, extended work in Mathematical Programming. [arxiv].

• Mitigating Gradient Bias in Multi-objective Learning: A Provably Convergent Approach
  Heshan D. Fernando, Han Shen, Miao Liu, Subhajit Chaudhury, Keerthiram Murugesan, Tianyi Chen
  ICLR 2023 (oral). [arxiv]

• Joint Unsupervised and Supervised Training for Automatic Speech Recognition via Bilevel Optimization
  A.F.M. Saif, Xiaodong Cui, Han Shen, Songtao Lu, Brian Kingsbury, Tianyi Chen
  ICASSP 2024.

• A Method For Bilevel Optimization With Convex Lower-level Problem
  Han Shen, Santiago Paternain, Gaowen Liu, Ramana Kompella, Tianyi Chen
  ICASSP 2024.

• Alternating projected SGD for equality-constrained bilevel optimization
  Quan Xiao, Han Shen, Wotao Yin, Tianyi Chen
  AISTATS 2023. [arxiv]

• A Single-timescale Analysis for Stochastic Approximation with Multiple Coupled Sequences
  Han Shen, Tianyi Chen
  NeurIPS 2022 (oral). [arxiv]

Reinforcement Learning

• On Entropy Control in LLM-RL Algorithms
  Han Shen
  ICLR 2026 [arxiv].

• Principled Penalty-based Methods for Bilevel Reinforcement Learning and RLHF
  Han Shen, Zhuoran Yang, Tianyi Chen
  ICML 2024, extended work in JMLR [arxiv].

• Towards Understanding Asynchronous Advantage Actor-critic: Convergence and Linear Speedup
  Han Shen, Kaiqing Zhang, Mingyi Hong, Tianyi Chen
  IEEE Transactions on Signal Processing. [arxiv]

• Adaptive Temporal Difference Learning with Linear Function Approximation
  Tao Sun, Han Shen, Tianyi Chen, Dongsheng Li
  TPAMI. [arxiv]

• Byzantine-resilient Decentralized Policy Evaluation with Linear Function Approximation
  Zhaoxian Wu, Han Shen, Tianyi Chen, Qing Ling
  IEEE Transactions on Signal Processing. [arxiv]

• Distributed Offline Policy Optimization Over Batch Data
  Han Shen, Songtao Lu, Xiaodong Cui, Tianyi Chen
  AISTATS 2022. [paper]