2026· Annual Meeting of the Association for Computational Linguistics· pp. 41764-41799· 0 citations· 36 references
Computer Science
TL;DR
CERL (Condition-node Expert-regularized Reinforcement Learning), a framework that leverages expert-regularized reinforcement learning to preserve semantic faithfulness, while employing a factorized policy that aggregates sequential condition-node decisions into a single decision unit to alleviate credit assignment challenges is introduced.
Abstract
Behavior trees provide a transparent and modular structure for encoding expert-designed policies, enabling interpretable decision-making in complex tasks. Yet, applying behavior trees to high-dimensional perceptual inputs such as images or language is challenging as defining symbolic predicates over raw perceptual data is non-trivial. While state-of-the-art large multimodal models (such as vision-language models) can overcome this issue by utilizing natural language queries over perceptual inputs, they incur high computational cost, making them unsuitable for many applications. Imitation learning offers a way to distill these expert models into compact models, though it requires extensive supervision. In contrast, reinforcement learning reduces the need for costly supervision but risks misalignment of condition nodes with their intended semantics as well as poor credit assignment. To address these challenges, we introduce CERL (Condition-node Expert-regularized Reinforcement Learning), a framework that leverages expert-regularized reinforcement learning to preserve semantic faithfulness, while employing a factorized policy that aggregates sequential condition-node decisions into a single decision unit to alleviate credit assignment challenges. Experiments across seven tasks from the GymCards, FrozenLake, and BabyAIText suites demonstrate that our framework outperforms pure imitation learning or reinforcement learning baselines, retains strong agreement with expert decisions, and achieves substantial gains in inference speed and model size over expert models. Our implementation is available in https://github.com/HyosikMoon/CERL .
This work introduces StructReward, a compute-efficient framework that provides dense reinforcement signals through structured step-level reward alignment and substantially reduces the computational overhead of multimodal reinforcement learning.
Designing effective reward functions remains a major bottleneck in Reinforcement Learning (RL). Recent work uses large foundation Vision-Language Models (VLMs) as reward models, computing text-observation similarity to bypass manual reward engineering. Although promising, these rewards are often noisy and unreliable, limiting their direct utility during deployment. We present Structure-Aware Fine-Tuning (SAFT), a simple, self-supervised method that refines these imperfect reward signals online without access to ground-truth supervision. SAFT leverages intrinsic structural priors to regularize the VLM's latent space via LoRA adapters. We rigorously evaluate SAFT across a spectrum of base model capabilities to demonstrate its versatility. Our results show that SAFT consistently denoises the reward landscape, yielding faster policy convergence and substantially improved alignment (EPIC distance) relative to the underlying base model, suggesting that failures can often be attributed to structural brittleness rather than semantic misunderstanding. By replacing extensive human preference annotation with structural inductive biases inherent to the task, SAFT offers a scalable path for stabilizing text-conditioned RL and underscores the broader value of incorporating task structure as a general inductive bias.
Pyrros Koussios, Chenhao Li, Xin Chen et al.· 0 citations
This work proposes $O^2-CritiCuRL, a novel curriculum reinforcement learning framework that introduces critical-step awareness through an iterative offline-online paradigm, and employs a progressive step-level reinforcement learning strategy, where truncated chains guide the model to infer missing steps and refine its reasoning.
Wendi Deng, Hang Du, Guoshun Nan et al.· arXiv.org· 0 citations
Post-training VLA policies typically rely on supervised fine-tuning with costly expert demonstrations or reinforcement learning with expensive and potentially unstable real-world exploration. World models offer a promising alternative by evaluating candidate behaviors through imagined futures, yet effective post-training requires more than accurate prediction: imagination must be scheduled where it is useful, bounded within reliable horizons, and translated into trustworthy policy supervision. In robotic manipulation, the value of imagination varies substantially across execution stages, while extended rollouts can accumulate prediction errors and introduce unreliable learning signals. We introduce WISE (World-model-guided Imagination Scheduling for Efficient Post-training of Vision-Language-Action Models), a unified framework that coordinates when and how world-model imagination is used during policy refinement. WISE selectively invokes imagination at interaction-relevant states, performs bounded multi-view rollouts, evaluates candidate futures using progress and completion signals, and uses their relative outcomes to refine actions generated from real interaction contexts. Extensive experiments with both $\pi_0$ and $\pi_{0.5}$ demonstrate consistent improvements across diverse manipulation tasks while reducing GPU computation time by approximately 80% compared with full imagination. Real-world evaluations further show substantial gains in robustness and generalization under diverse real-world distribution shifts.
Chen-Hao Zhang, Han-Yu Zhao, Hang Cheng et al.· 0 citations
This paper explores post-training reinforcement learning (RL), specifically GRPO, to directly align autoregressive perception models with their evaluation metrics, and designs an RL framework that addresses perception-specific challenges: reward design for set-structured outputs and multi-head sampling control.
Sofian Chaybouti, Yasser Dahou, N. Huynh et al.· 0 citations
Deep neural networks often suffer significant accuracy degradation when exposed to real-world image corruptions and distribution shifts. To overcome the limitations of fixed, input-agnostic test-time augmentation (TTA), an adaptive framework is proposed that learns per-sample transformations via reinforcement learning. Augmentation selection is cast as a Markov decision process and proximal policy optimization (PPO) agents are trained to choose sample-specific transforms under a composite reward combining classifier confidence gains with a self-consistency KL-divergence penalty on the model's own softmax outputs, thereby preserving overall belief stability. On clean CIFAR-10 (1 000 samples), the adaptive ensemble raises accuracy from 88.5% (baseline) and 87.3% (static TTA) to 90.0% (+1.5 pp). On CIFAR-10-C (15 corruptions × 5 severities; 1 000 images per condition), pooled top-1 accuracy improves from 75.7% (baseline) and 74.3% (static TTA) to 76.4% (+0.7 pp), and exceeds a TENT entropy-minimization baseline (75.9%) while operating in a strictly label-free regime that updates no model weights. Per-corruption gains are consistently positive across noise, blur, weather, and compression distortions, with the adaptive policy outperforming TENT on texture and compression corruptions where input-space transforms are most effective. These findings demonstrate that learned, per-sample augmentation policies improve robustness and reliability of deep vision models under diverse image conditions, against a strong baseline classifier.
T. Mittal, A. Dubey, Dharmender Saini et al.· Scientific Reports· 0 citations
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