Training methods
arxiv arXiv cs.AI · 8d ago

Learning Fair Pareto-Optimal Policies in Multi-Objective Reinforcement Learning

The paper introduces a framework for multi-policy multi-objective reinforcement learning that learns a set of Pareto-optimal policies ensuring fairness across diverse user preferences. It proves fair policies remain within the convex coverage set for concave welfare functions like GGF and proposes three algorithms that incorporate non-stationary and stochastic policies to adapt to historical inequities. Empirical results show these methods effectively learn fair policies across multiple domains.

arxiv arXiv cs.AI · 9d ago

Meta-Knowledge Reutilization in Reinforcement Learning

A new framework learns task-level knowledge on a simplified agent and transfers it to heterogeneous agents. It uses Bayesian non-parametric priors and a high-level policy to generate task guidance, with a semantic-magnitude interface and temporal adaptor to align meta-knowledge with embodiment-specific controllers. Experiments show 94.75% to 99.79% reduction in final-step tracking error and comparable performance using 23.8% of the interaction data of state-of-the-art methods.

arxiv arXiv cs.AI · 9d ago

Kolmogorov Regression for Robust Diffusion Policies

A backward Kolmogorov equation lifts diffusion policies to a Cameron-Martin space, replacing stochastic score matching with a deterministic PDE. This approach achieves convergence bounds tied to kernel effective rank, improved trajectory regularity, and a failure detector without rewards, showing 17% higher reward and 67.6% reduced drift on PushT, and 28.4% lower RMSE with perfect bottleneck detection on a manufacturing line. Hamilton-Jacobi theory reduces deadlock events by 96% in simulations.

arxiv arXiv cs.CL · 9d ago

Expressivity Analysis of Hierarchical Modelling in Deep Transformers

This paper analyzes deep transformer expressiveness using bounded-depth grammars. It constructs transformers with positional attention where model depth scales linearly with grammar depth, and neuron count grows quadratically with production rules. The results support the linear representation hypothesis by showing these models can encode abstract grammatical states in low-dimensional, linearly separable subspaces.

arxiv arXiv cs.CL · 9d ago

LLM-Designed Training Environment for RL with Multi-Agent Reasoning

The LLM-as-Environment-Engineer framework uses LLMs to automatically redesign training environments in reinforcement learning by analyzing failure trajectories and contextual data. On the MAPF-FrozenLake testbed, it outperforms larger proprietary LLMs and fixed-environment baselines, with Qwen3-4B achieving the strongest aggregate performance. Analysis shows that failure evidence and preserved working configurations are key, and the current RL checkpoint performs better than the base model as an environment engineer.

arxiv arXiv cs.CL · 9d ago

Dynamic Rollout Editing Reduces Overthinking in RL-Trained Reasoning Models

Dynamic Rollout Editing (DRE) addresses overthinking in RL-trained reasoning models by modifying successful trajectories post-answer emergence. DRE preserves the correct reasoning prefix while editing unnecessary continuation, weakening the credit assigned to redundant thinking without penalizing valid reasoning. Experiments across diverse tasks demonstrate its effectiveness in reducing overthinking.

arxiv arXiv cs.CL · 10d ago

Contrastive-Difference CKA Reveals Concept-Specific Alignment Across LLM Architectures

A training-free diagnostic, contrastive-difference CKA (CKA_Delta), identifies concept-specific structural alignment across language model architectures. It detects geometric convergence and functional transfer across six concept domains, including non-instructional tasks, with significant discrimination where standard CKA fails. Results suggest universality may strengthen with model scale, though further validation is needed.