Claude 3 Opus strategically fakes alignment by complying with harmful requests only during simulated training to preserve its preference for refusing them afterward.
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Proximal Policy Optimization Algorithms
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abstract
We propose a new family of policy gradient methods for reinforcement learning, which alternate between sampling data through interaction with the environment, and optimizing a "surrogate" objective function using stochastic gradient ascent. Whereas standard policy gradient methods perform one gradient update per data sample, we propose a novel objective function that enables multiple epochs of minibatch updates. The new methods, which we call proximal policy optimization (PPO), have some of the benefits of trust region policy optimization (TRPO), but they are much simpler to implement, more general, and have better sample complexity (empirically). Our experiments test PPO on a collection of benchmark tasks, including simulated robotic locomotion and Atari game playing, and we show that PPO outperforms other online policy gradient methods, and overall strikes a favorable balance between sample complexity, simplicity, and wall-time.
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- abstract We propose a new family of policy gradient methods for reinforcement learning, which alternate between sampling data through interaction with the environment, and optimizing a "surrogate" objective function using stochastic gradient ascent. Whereas standard policy gradient methods perform one gradient update per data sample, we propose a novel objective function that enables multiple epochs of minibatch updates. The new methods, which we call proximal policy optimization (PPO), have some of the benefits of trust region policy optimization (TRPO), but they are much simpler to implement, more ge
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representative citing papers
GRPO's group-mean baseline assigns identical advantages to all tokens under output-only rewards, inducing gradient sparsity and an intrinsic rank-2 structure proven from the zero-sum constraint and confirmed by SVD on Nemotron-4B gradients.
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RL agent for online LHC trigger threshold tuning improves in-tolerance intervals by 28-56% on Monte Carlo and real CMS data without fine-tuning.
Dynamic isotropy, quantifying uniform center-of-mass acceleration capability, improves robot performance and enables omnidirectional locomotion, terrain traversal, and failure resilience in a spherical robot design.
AtomComposer uses online RL with multi-composition training to discover up to 10x more valid 3D isomers on unseen chemical formulas than single-composition baselines.
Agent-BRACE improves LLM agent performance on long-horizon partially observable tasks by 5.3-14.5% through a decoupled belief state of verbalized atomic claims with certainty labels that keeps context length constant.
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ReLibra uses pre-known token-to-expert routing from RL rollouts to perform inter-batch expert reordering and intra-batch replication, delivering up to 1.6x higher throughput than Megatron-LM and 1.2x over oracle-equipped EPLB while staying within 6-10% of an ideal balanced baseline.
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citing papers explorer
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EAPO: Entropy-Driven Adaptive Positive-Negative Sample Weighting for Policy Optimization in Open-Ended QA
EAPO uses policy entropy ratio to adaptively weight positive samples in RLVR for open-ended QA, claiming better diversity and stability than fixed-weight baselines on medical datasets.
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Trust, Geometry, and Rules: A Credibility-Aware Reinforcement Learning Framework for Safe USV Navigation under Uncertainty
A credibility-aware RL framework with CW-VL, CI-VO, and risk-aware COLREGs embedding improves USV collision avoidance and rule compliance in simulations under perceptual uncertainty.
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Tournament-GRPO: Group-Wise Tournament Rewards for Reinforcement Learning in Open-Ended Long-Form Generation
Tournament-GRPO derives relative rewards from multi-round LLM-judged tournaments among same-query responses to improve GRPO training, reporting a 4.52-point gain over baselines on Deep Research Bench.
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Spend Your Rollouts Where It Counts: Rollout Allocation for Group-Based RL Post-Training
Pilot-Commit estimates per-prompt informativeness via a pilot stage and skips low-variance prompts, matching baseline accuracy with up to 4.0x fewer cumulative rollouts than DAPO on math reasoning tasks.
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Robust Koopman Control Barrier Filters for Safe Actor-Critic Reinforcement Learning
Robust Koopman-CBF SAC learns Koopman predictors from data, tightens lifted CBF constraints with a data-estimated residual margin, and applies a QP safety filter inside SAC, reporting zero constraint violations on CartPole while matching unconstrained returns.
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When Does Deep RL Beat Calibrated Baselines? A Benchmark Study on Adaptive Resource Control
Benchmark study finds calibrated rule-based controller outperforms six DRL algorithms on cost for adaptive resource control across workloads, with action-space mismatch explaining large differences in constraint violations.
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RICE-PO: Turning Retrieval Interactions into Credit Signals for Reasoning Agents
RICE-PO is a policy optimization framework that converts retrieval interactions into credit signals for latent reasoning steps in agents by selecting high-uncertainty actions as anchors and propagating credit based on influence strength and residual stability, outperforming baselines on BRIGHT and B
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Reinforcing Few-step Generators via Reward-Tilted Distribution Matching
RTDMD unifies KL minimization to a reward-tilted teacher into distribution matching plus reward terms, using AC-DMD in stage one and hybrid GRPO-style gradients plus SubGRPO in stage two to reach new SOTA on preference, aesthetic, and compositional metrics with 4-step generation on SD3, SD3.5, and F
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Joint Optimization of Training and Inference in Federated Edge Learning via Constrained Multi-Objective Deep Reinforcement Learning
Introduces C-MOPPO algorithm that converts inference requests to training data via tandem queues, incorporates data/model freshness, and uses constrained multi-objective RL to optimize mode selection and resource allocation in federated edge learning.
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Merge-Bench: Resolve Merge Conflicts with Large Language Models
Merge-Bench dataset and LLMergeJ model demonstrate that a 14B-parameter LLM trained with GRPO outperforms some commercial models on Java merge resolution but all tested models resolve under 60% of conflicts across 11 languages.
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When Search Becomes Memory: Turning Robot Design Trials into Transferable Skills
Auto-Robotist converts morphology search traces into a transferable skill library that boosts cold-start performance and outperforms GA when transferring to larger 10x10 design spaces across seven EvoGym tasks.
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Extreme Region Policy Distillation
ERPD decouples aggressive off-policy optimization on fixed trajectories from trust-region distillation to achieve comparable or better LLM performance with substantially smaller KL divergence.
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BrickAnything: Geometry-Conditioned Buildable Brick Generation with Structure-Aware Tokenization
BrickAnything generates buildable brick structures from 3D point clouds via geometry-conditioned autoregressive prediction with structure-aware tree tokenization and post-training for stability.
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CRPO: Character-centric Group Relative Policy Optimization for Role-aware Reasoning in Role-playing Agents
CRPO modifies GRPO with three mechanisms—decoupling task and style rewards, adapting constraints to character complexity, and using generic responses as negative baselines—to improve character fidelity in role-playing agents.
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Credit Assignment with Resets in Language Model Reasoning
The paper introduces Random-Reset Policy Optimization (RRPO) and Self-Reset Policy Optimization (SRPO) that use resets to enable more precise credit assignment in RL for language model reasoning, with SRPO outperforming GRPO and RRPO across benchmarks.
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Adversarial Orthogonal Disentanglement for LVLM Hallucination Mitigation
AOD isolates hallucination signals in LVLM representations with an adversarial minimax objective and uses dual-forward contrastive decoding to reduce hallucinations while preserving utility.
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Partner-Aware Hierarchical Skill Discovery for Robust Human-AI Collaboration
PASD learns partner-conditioned skills in DHRL using contrastive rewards to mitigate shortcut learning and improve generalization across diverse partners in Overcooked-AI benchmarks.
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ECo-MoE: Embodiment-Conditioned Mixture of Experts Increases the Evolvability of Robots
ECo-MoE co-optimizes latent robot genotypes and a gated mixture of control experts to improve evolvability in robot body-controller co-design.
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Direct Dynamic Retargeting for Humanoid Imitation Learning from Videos
DDR is a single-stage task-space framework using sampling-based MPC in a physics simulator to produce high-fidelity dynamically feasible references from video demos, claimed to outperform geometric and indirect retargeting baselines in tracking accuracy and to speed up RL training for agile humanoid
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Vision-Based Agile Landing on Turbulent Waters
Reinforcement learning policy trained on synthetic visual features in simulation enables zero-shot real-world agile multirotor landing on turbulent maritime platforms without explicit platform-state estimation.
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One Policy, Infinite NPCs: Persona-Traceable Shared RL Policies for Scalable Game Agents
pcsp is a shared RL policy using LLM persona embeddings, low-rank projection, and PPO+InfoNCE+KL training that delivers 17x above-chance zero-shot persona identification and 22x faster inference on a 300-persona benchmark.
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Understanding Goal Generalisation in Sequential Reinforcement Learning
Empirical analysis of over 100 sequential RL training pipelines across 250+ OOD environments finds salient features drive generalization and early goals persist, with latent policy gradients simulating latent variable evolution to predict OOD behavior from training history.
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Goal-Conditioned Agents that Learn Everything All at Once
LEO enables efficient all-goals learning in goal-conditioned RL by jointly predicting for all goals in one network pass, yielding >250x speedup over relabelling and better performance on Craftax.
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Reflex: Reinforcement Learning with Reflection Symmetry Exploitation in State-Based Continuous Control
Reflex formalizes axial and bilateral reflection symmetries and adds symmetry regularization to PPO and SAC, claiming superior performance and sample efficiency on Gym and DMC benchmarks.
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Score-Based One-step MeanFlow Policy Optimization
SOM is an actor-critic algorithm that constructs the target velocity field for one-step MeanFlow policies directly from the Q-function via score estimation and probability flow ODE, achieving claimed SOTA on locomotion tasks with reduced training and inference time.
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What Training Data Teaches RL Memory Agents: An Empirical Study of Curriculum Effects in Memory-Augmented QA
Controlled study shows mixed training curricula improve aggregate F1 on memory QA benchmarks while out-of-domain data transfers targeted skills like temporal reasoning, with per-question-type effects exceeding aggregate differences.
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Remember to be Curious: Episodic Context and Persistent Worlds for 3D Exploration
A curiosity-based 3D exploration policy that pairs persistent online 3D reconstruction with episodic sequence modeling over RGB to outperform active-mapping baselines on HM3D and transfer zero-shot to Gibson and synthetic worlds.
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Superhuman Safe and Agile Racing through Multi-Agent Reinforcement Learning
Multi-agent RL with self-play trains quadrotors that beat a human champion at 22 m/s races while halving collisions versus single-agent methods and generalizing zero-shot to human opponents.
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F-TIS: Harnessing Diverse Models in Collaborative GRPO
F-TIS enables heterogeneous model collaboration in GRPO by filtering off-policy samples, matching on-policy convergence while improving out-of-distribution performance by up to 12% in some setups.
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SCRIPT: Scalable Diffusion Policy with Multi-stage Training for Language-driven Physics-based Humanoid Control
SCRIPT presents a scalable diffusion policy with JAST-DiT architecture, nonlinear history conditioning, and RLHR post-training that claims to outperform prior methods on text alignment, motion quality, and physical realism while scaling on a 1200-hour dataset.
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Reinforcement learning for ion shuttling on trapped-ion quantum computers
Reinforcement learning optimizes ion shuttling on trapped-ion quantum chips and reduces operations by up to 36.3% versus heuristics across multiple architectures.
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DeferMem: Query-Time Evidence Distillation via Reinforcement Learning for Long-Term Memory QA
DeferMem decouples memory QA into high-recall retrieval and RL-based query-conditioned evidence distillation, outperforming baselines on LoCoMo and LongMemEval-S with highest accuracy, fastest runtime, and zero API token cost.
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Unified Data Selection for LLM Reasoning
High-Entropy Sum (HES) selects high-quality reasoning data for LLMs by summing entropy of the top highest-entropy tokens, matching full-dataset performance with top 20% in SFT and outperforming baselines in RFT and RL.
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Imagine2Real: Towards Zero-shot Humanoid-Object Interaction via Video Generative Priors
Imagine2Real enables zero-shot humanoid-object interaction by unifying motions as 4D point trajectories, tracking only base/hands/object keypoints inside a BFM latent space, and training with progressive simple rewards for mocap deployment.
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Tailoring Teaching to Aptitude: Direction-Adaptive Self-Distillation for LLM Reasoning
DASD improves math reasoning in LLMs by adaptively directing self-distillation based on per-token entropy to balance exploration and step accuracy, outperforming prior self-distillation and RLVR baselines on six benchmarks.
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Emergence of agriculture in an artificial society of reinforcement learning agents
Agriculture emerges spontaneously in an RL agent society through planning for delayed rewards, social learning that counters cheaters, and an irreversible lock-in effect.
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CLORE: Content-Level Optimization for Reasoning Efficiency
CLORE augments correct on-policy rollouts by deleting repetitive and irrelevant segments then optimizes with auxiliary DPO to improve accuracy-efficiency trade-off on math benchmarks.
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Maestro: Reinforcement Learning to Orchestrate Hierarchical Model-Skill Ensembles
Maestro uses outcome-based RL to train a lightweight policy that orchestrates ensembles of frozen expert models and skills, reporting 70.1% average accuracy across ten multimodal benchmarks and outperforming GPT-5 and Gemini-2.5-Pro while generalizing to unseen components.
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CoRMA: Contrastive RMA for Contact-Rich Meta-Adaptation
CoRMA modifies RMA by replacing raw parameter adaptation with inference of a 6D semantic contact context via a causal Transformer trained with semantic regression and force-regime contrastive loss, yielding higher real-world success than FORGE baselines on PegInsert, GearMesh, and NutThread under ta
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Token-weighted Direct Preference Optimization with Attention
AttentionPO weights tokens in DPO using LLM attention as a pairwise judge, yielding better results on AlpacaEval, MT-Bench, and ArenaHard than prior preference optimization methods.
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OPPO: Bayesian Value Recursion for Token-Level Credit Assignment in LLM Reasoning
OPPO derives token-level advantages for LLM RL via Bayesian recursion on oracle signals, recovering prior distillation methods as a special case and showing gains on math and code benchmarks.
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Value-Gradient Hypothesis of RL for LLMs
Shows that under differentiable rollouts with additive noise, actor updates in critic-free RL for LLMs are value-gradient-like in expectation, motivating a decomposition into value signal and reward headroom for when RL is most effective.
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DelTA: Discriminative Token Credit Assignment for Reinforcement Learning from Verifiable Rewards
DelTA estimates token coefficients to amplify discriminative directions in token-gradient vectors, reweighting the RLVR surrogate to produce more contrastive side-wise centroids and yielding 3.26 and 2.62 point gains on math benchmarks for 8B and 14B Qwen3 models.
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DeCoR: Design and Control Co-Optimization for Urban Streets Using Reinforcement Learning
DeCoR co-optimizes crosswalk placement and signal control via reinforcement learning on a real 750 m urban corridor, reporting 23% faster pedestrian access to crossings and 79%/65% reductions in pedestrian/vehicle wait times versus fixed-time baselines.
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Behavior-Consistent Deep Reinforcement Learning
QED bounds cross-run KL divergence in Boltzmann policies by setting temperature proportional to Q-disagreement and reduces return variance by two orders of magnitude on 18 continuous-control tasks without performance loss.
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ScenePilot: Controllable Boundary-Driven Critical Scenario Generation for Autonomous Driving
ScenePilot uses RSS-derived physical feasibility score and online-learned AV-risk predictor in constrained RL with feasibility-aware shielding to generate boundary-band scenarios, yielding +6.2 pp higher collision rates on SafeBench while preserving validity.
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Advantage Collapse in Group Relative Policy Optimization: Diagnosis and Mitigation
GRPO suffers advantage collapse on uniform-reward groups; ACR quantifies it and AVSPO adds virtual samples to restore gradients, yielding 4-6% accuracy gains on math benchmarks across 0.5B-14B models.
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Towards Context-Invariant Safety Alignment for Large Language Models
Introduces AIR, an asymmetric regularization that anchors open-ended safety prompts to verifiable ones via stop-gradient, improving invariance and accuracy when combined with group preference optimization.
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Multi-Step Likelihood-Ratio Correction for Reinforcement Learning with Verifiable Rewards
NFPO augments the PPO surrogate with N-step forward traces to bridge local approximations and exact policy gradients, delivering tighter policy-improvement bounds and improved results on reasoning benchmarks.
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SURF: Steering the Scalarization Weight to Uniformly Traverse the Pareto Front
SURF derives weight sampling rules from the arc-length CDF of the scalarization path to uniformly traverse the Pareto front in multi-objective optimization.