Multi-objective reinforcement learning (MORL) aims to optimize policies in the presence of conflicting objectives, where linear scalarization is commonly used to reduce vector-valued returns into scalar signals. While effective for certain preferences, this approach cannot capture fairness-oriented goals such as Nash social welfare or max-min fairness, which require nonlinear and non-additive trade-offs. Although several online algorithms have been proposed for specific fairness objectives, a unified approach for optimizing nonlinear welfare criteria in the offline setting-where learning must proceed from a fixed dataset-remains unexplored. In this work, we present FairDICE, the first offline MORL framework that directly optimizes nonlinear welfare objective. FairDICE leverages distribution correction estimation to jointly account for welfare maximization and distributional regularization, enabling stable and sample-efficient learning without requiring explicit preference weights or exhaustive weight search. Across multiple offline benchmarks, FairDICE demonstrates strong fairness-aware performance compared to existing baselines.
PyCFRL: A Python library for counterfactually fair offline reinforcement learning via sequential data preprocessing
Department of Statistics, University of Michigan, USA（统计学系，密歇根大学）；Department of Biostatistics, University of Michigan, USA（生物统计学系，密歇根大学）；Department of Statistics, London School of Economics, UK（统计学系，伦敦经济学院）；Department of Health Behavior and Health Equity, School of Public Health, University of Michigan, USA（健康行为与健康公平系，公共卫生学院，密歇根大学）
Hybrid Adaptive Conformal Offline Reinforcement Learning for Fair Population Health Management
Waymark, San Francisco, CA, USA（Waymark）；San Francisco General Hospital, University of California San Francisco, San Francisco, CA, USA（旧金山通用医院，加州大学旧金山分校）；University of California San Francisco, San Francisco, CA, USA（加州大学旧金山分校）；University of Pennsylvania, Philadelphia, PA, USA（宾夕法尼亚大学）
SIGMA: Symmetry-aware, Intelligent, Geometric, Multi-faced Adaptive Traffic Control for Reliable Intelligent Transportation Systems
Indian Statistical Institute（印度统计研究所）；Sorbonne University Abu Dhabi（阿布扎比索邦大学）；Sorbonne Center for Artificial Intelligence（索邦人工智能中心）；SQC & OR（统计质量控制与运筹学研究室）
