From Trainee to Trainer: LLM-Designed Training Environment for RL with Multi-Agent Reasoning
Abstract: Reinforcement learning pipelines for LLM training often rely on manually redesigned environments between stages, requiring practitioners to heuristically infer which configuration will best improve the current policy. To automate this process, we propose the LLM-as-Environment-Engineer framework in which the current policy model analyzes failure trajectories together with contextual information and proposes modifications to the next-stage training environment configuration. We also introduce MAPF-FrozenLake, a controllable testbed whose generator exposes multi-dimensional environment configurations, making it suitable for studying and benchmarking environment redesign. On this testbed, we condition the environment engineer on structured summaries of policy behavior, failure cases, and environment statistics, from which it produces the configuration for the next training stage. With Qwen3-4B as the backbone, our framework achieves the strongest aggregate performance on our benchmarks, outperforming larger proprietary LLMs (e.g., GPT, Gemini) and fixed-environment training baselines. We further analyze which forms of context are most effective, finding that successful environment updates rely on failure evidence and preserve configurations that already work. Interestingly, the current RL checkpoint serves as a better environment engineer than the original base model, suggesting that policy learning improves the model's ability to diagnose its remaining weaknesses.
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Overview
This paper asks a simple question with a big twist: what if a learning model could act like its own coach? Instead of humans constantly tweaking the training setup, the model reviews where it fails, then redesigns the next “practice environment” to fix those weaknesses. The authors build a system that lets a LLM do exactly that and test it in a controlled puzzle world.
The main questions
- Can a LLM analyze its own mistakes and then redesign the training environment so it learns better next time?
- What information does the model need to make good decisions about the next training round?
- Is a trained model better at this “environment engineering” than the original, untrained model?
- Does smart redesign mean “make it harder,” or does it mean “target what’s actually missing”?
How they tested the idea
A quick refresher: the task world
The team uses a puzzle called Multi-Agent Path Finding (MAPF). Imagine a grid with several colored agents (little characters), each trying to reach a matching colored goal. There are “holes” (blocked cells) you must avoid, and agents aren’t allowed to bump into each other or swap places. Sometimes you need to “wait” a turn to avoid a collision.
They introduce a controllable world called MAPF-FrozenLake. A generator makes many puzzle instances by turning a few “knobs”:
- data ratio: how many puzzles of each grid size (3×3 up to 10×10) to include
- hole ratio: how many blocked cells to place (how cluttered the map is)
- wait ratio: how often puzzles require a “wait” action to resolve conflicts
By adjusting these knobs, you can decide what kind of practice the model gets next round.
The “environment engineer” loop
Think of the model as both player and coach:
- Train: The model practices on puzzles created from the current configuration.
- Evaluate: Check how well it did and where it failed (for each grid size and failure type).
- Design: The model reads a structured report of its own performance and proposes a new configuration for the generator (how many of each puzzle size, how cluttered, how many “wait” cases, etc.) for the next training round.
This repeats for several rounds, so the practice set evolves based on evidence rather than guesswork.
What information the model looks at
The “coach” LLM reads:
- A failure breakdown (what went wrong and on which sizes: parsing errors, illegal moves, collisions, going out of bounds, not reaching goals).
- A short training history (what changed before and what happened).
- A few guidelines and minimal training details (e.g., which round we’re in). The authors tested different combinations to see what helps most.
How learning and scoring worked (in everyday terms)
The model learns by trial and error (this is reinforcement learning). It’s rewarded for giving:
- Correct solutions (paths that are parsable, legal, reach goals, avoid holes, stay on the grid, and don’t collide).
- Concise answers (not overly long or chatty).
Early on, the system cares more about keeping answers short; as the model learns to be brief, the reward shifts to emphasize correctness even more.
They use a compact open model, Qwen3-4B, as the “player,” and compare against bigger commercial LLMs (like GPT and Gemini) acting as environment designers.
What they found
- The self-engineering framework wins. The small Qwen3-4B, when trained and allowed to redesign its own training environment, achieved the best overall results on harder tests (with 3, 4, and 5 agents), beating larger proprietary models and a strong fixed-environment baseline. In plain terms: a smaller model with smart practice planning outperformed bigger models.
- Improvements were clear and consistent. Compared to the best commercial baseline, the system raised accuracy by about 5–6 percentage points and improved “best-quality” (optimal) solutions by about 2–3 points. Compared to using a single random training setup, the gains ranged roughly +4 to +11 points in accuracy and +2 to +6 in optimality, depending on the test.
- Smarter, not just harder. The model didn’t just crank up difficulty. It used failure evidence to:
- Keep settings that already worked (don’t “fix” what isn’t broken).
- Increase challenge where the model was ready for it.
- Reduce focus on puzzles that were so hard they weren’t teaching anything yet (e.g., down-weighting the largest grids when they stopped providing useful learning signal).
- The trained model is a better coach than the untrained one. The current “checkpoint” (a saved version of the model mid-training) made better environment decisions than the original base model. Training made it more self-aware about its weaknesses, so it could target the right practice.
- Less is more for context. Giving the designer too many low-level RL details was distracting. Simple “bookkeeping” (what round we’re in, how many epochs) plus solid, factual failure reports worked best.
Why this is important: It shows that targeted practice, guided by real mistakes, helps the model learn faster and generalize better, even to puzzles with more agents than it saw during training.
Why it matters and what’s next
If models can become their own environment designers, humans won’t need to handcraft training curricula as much. This could:
- Make training more efficient and less labor-intensive.
- Lead to systems that continually improve by choosing practice that addresses their current weaknesses.
- Help smaller, cheaper models close the gap with (or even beat) larger ones by training smarter.
Limitations and future steps:
- The study focuses on one controlled puzzle world. It’s a great testbed, but we don’t yet know how well the approach transfers to very different tasks (like robots, web agents, or open-ended games).
- The model can tune the generator’s settings but can’t invent entirely new game mechanics yet.
- Exploring other learning setups (beyond this specific reinforcement learning pipeline) could broaden impact.
In short: this paper shows a practical way for an AI to become both the trainee and the trainer—learning from its mistakes and redesigning its own practice to improve faster and smarter.
Knowledge Gaps
Knowledge gaps, limitations, and open questions
The paper leaves the following issues unresolved; each item is framed to suggest concrete next steps for future work.
- External validity: Does the framework transfer beyond MAPF-FrozenLake to domains with different dynamics (e.g., continuous control, stochastic environments, web tasks, robotics) and distinct failure taxonomies?
- Generator dependence: How well do results generalize across different MAPF generators (e.g., maze-based, random obstacle fields, different solvers than CBS) and under distribution shifts in obstacle/topology statistics?
- Structural environment changes: The engineer can only tune per-size ratios and two difficulty knobs (hole_ratio, wait_ratio); how to extend to structural generator edits (new mechanics, action sets, topology classes) and search or learn over the space of generator architectures?
- Agent-count scaling: Training uses only 2-agent data; what are the benefits/risks of also training on mixed agent counts, and what schedules best promote scaling to 5+ or 10+ agents?
- Long-horizon stability: The study runs three rounds with a fixed budget; do curricula oscillate or converge under many more iterations, larger budgets, or adaptive stopping criteria?
- Fixed validation overfitting: Using a fixed 2-agent validation set across rounds risks the engineer overfitting its redesigns to that set; would rolling or cross-validated validation reduce this risk?
- Sample efficiency: How much does environment engineering reduce samples-to-target compared to fixed curricula, and how do learning curves differ across settings?
- Statistical robustness: Results are reported for single runs; what is the variance across seeds, and are improvements statistically significant with confidence intervals?
- Engineer identity and scaling: When does the “current checkpoint as engineer” stop paying off—does a separate, possibly larger or ensemble engineer outperform self-engineering, and how does this scale with learner capability?
- Baseline fairness: Proprietary LLMs are used as engineers, not learners; do conclusions hold under cross-combinations (e.g., large LLM learner + small engineer, or vice versa) to disentangle learner vs. engineer contributions?
- RL algorithm generality: The pipeline centers on GRPO with a particular reward; how do results change with PPO/TRPO/A2C, actor–critic with value baselines, or policy-gradient variants with different KL penalties?
- Reward-shaping sensitivity: The accuracy reward’s , adaptive weight schedule, and length penalties are fixed; what is the sensitivity to these choices, and do alternative shaping schemes alter engineer decisions?
- Joint reward–environment design: The engineer cannot modify the reward; does jointly adapting reward and environment (with constraints) outperform environment-only updates, and how to prevent reward hacking in that setting?
- Feedback modalities: The engineer uses failure counts and simple aggregates; do richer signals (advantage/value estimates, uncertainty, value disagreement, entropy maps, gradient norms, trajectory attribution) improve redesign quality?
- Noisy/partial logging: How robust is redesign to missing, delayed, or corrupted failure statistics? What denoising or Bayesian inference over failure rates is needed to maintain reliable decisions?
- Causal attribution: Which specific configuration edits cause which performance deltas? Controlled interventions and counterfactual analyses are needed to isolate edit→effect relationships per map size and failure mode.
- Diversity vs. difficulty: The framework focuses on valid/optimal rates; how to ensure training-distribution diversity (e.g., conflict patterns, path overlaps, start–goal distances) rather than drifting toward narrow difficulty bands?
- Degenerate/easy distributions: Although reward hacking is constrained, the engineer could still over-concentrate on overly easy regimes; what safeguards (e.g., minimum-entropy constraints or diversity budgets) prevent collapse?
- Prompt sensitivity: Redesign quality may depend on prompt phrasing and reasoning style; how do chain-of-thought, tool use (e.g., small calculators/solvers), or prompt tuning affect outcomes?
- Continual/online adaptation: The paper uses staged rounds; can the engineer operate in a streaming or online manner (e.g., per-batch updates), and what stabilization (e.g., trust regions) are needed?
- Multi-objective trade-offs: Valid/optimal rates are treated as primary; how to incorporate auxiliary objectives (e.g., robustness, inference latency, interpretability) into the redesign decision?
- Compute–benefit trade-off: What is the net gain per GPU-hour of environment engineering versus carefully tuned static curricula or simpler heuristics?
- Failure modes of the framework: Under what conditions does redesign hurt performance (e.g., catastrophic forgetting of small maps, over-editing)? Can automatic “do no harm” constraints or rollback mechanisms mitigate this?
- Theory and guarantees: The framework lacks a bilevel or meta-RL formalization; what are the objective, stability conditions, and (if any) regret/convergence guarantees for policy-conditioned environment design?
- Robust generalization tests: Evaluation focuses on valid/optimal rates within the MAPF-FrozenLake family; can the learned policy transfer to out-of-family tasks (e.g., different grid aspect ratios, non-Manhattan moves, dynamic obstacles)?
- Monitoring and diagnostics: Beyond valid/optimal, which additional diagnostics (e.g., distributions of conflicts resolved, wait usage, path suboptimality histograms) best guide redesign and detect overfitting or collapse?
Practical Applications
Practical Applications of “LLM-as-Environment-Engineer” and MAPF-FrozenLake
The paper introduces a closed-loop framework where the current RL-trained LLM diagnoses its own failure patterns and redesigns the next-stage training environment by editing a parameterized generator. It also provides MAPF-FrozenLake, a controllable, multi-parameter benchmark to study environment redesign. Below are actionable, real-world applications derived from the framework’s findings, methods, and innovations.
Immediate Applications
- Adaptive curriculum and environment design for RL pipelines
- Sector: software/AI tooling, robotics, games
- Tools/products/workflows:
- Plug-in “Environment Engineer” module for RL frameworks (e.g., Ray RLlib, Gymnasium/PettingZoo, VERL, vLLM) that:
- 1) parses structured failure logs,
- 2) proposes generator config updates (e.g., task mix, difficulty knobs),
- 3) enforces constraints and regenerates training batches.
- Dashboard for “TRAIN → EVAL → DESIGN” loops with history, per-failure breakdowns, and round-aware bookkeeping.
- Assumptions/dependencies: availability of a parameterized environment generator (with exposed knobs like size/difficulty/interaction density), structured failure taxonomies, and stable validation sets to avoid overfitting.
- Targeted scenario generation for autonomous systems testing (simulation)
- Sector: automotive/AVs, drones, warehouse robotics
- Tools/products/workflows:
- Integrate with CARLA, AirSim, LGSVL, Isaac Sim or similar to adjust distributions over scenario parameters (e.g., traffic density, pedestrian behavior, weather, obstacle layouts) based on disengagement/failure logs.
- “Weakness-focused” scenario packs for regression testing and pre-deployment stress tests.
- Assumptions/dependencies: simulators must support programmatic control of scenario parameters; reliable mapping from real-world failures to simulator knobs; guardrails to prevent collapsing learning signal by oversampling unlearnable cases.
- Failure-driven software testing and fuzzing
- Sector: software engineering/DevOps
- Tools/products/workflows:
- LLM-driven configuration of property-based test generators (e.g., Hypothesis) or fuzzers (e.g., AFL/LibFuzzer) to rebalance inputs toward recent failure-inducing patterns while preserving coverage of previously stable areas.
- CI/CD integration that ingests test failures and automatically edits test distributions for the next run.
- Assumptions/dependencies: test generators must be parameterizable; failure signals (e.g., stack traces, assertions) must be consistently categorized; separation of test-set tuning vs. acceptance criteria to avoid overfitting.
- Adaptive content and curriculum generation in education
- Sector: education/edtech
- Tools/products/workflows:
- Parameterized problem generators for math/logic/programming that shift ratios across topic areas, difficulty bands, and error-prone skills based on per-learner failure analysis.
- “Round-aware” tutoring systems that preserve mastered skills while increasing exposure to near-frontier tasks.
- Assumptions/dependencies: validated item banks or controllable generators with clear parameters; privacy-preserving logging of learner errors; pedagogical oversight to avoid counterproductive difficulty spikes.
- Game AI training and balancing
- Sector: gaming
- Tools/products/workflows:
- Use the framework to tune bot-training curricula in RTS/strategy games by adjusting map complexity, resource distribution, and multi-agent conflict frequency based on failure traces.
- Ops tooling to preserve configurations that already yield healthy learning signals while selectively targeting weak tactics.
- Assumptions/dependencies: game engines or ML-Agents-like toolkits must expose scenario parameters; reliable evaluation metrics (validity/optimality analogs) for bot performance.
- Research benchmarking for environment redesign
- Sector: academia
- Tools/products/workflows:
- Immediate use of MAPF-FrozenLake (GitHub/Hugging Face provided) to benchmark environment-redesign algorithms and study how evidence-driven updates outperform naïve difficulty scaling.
- Comparative studies of context modules (failure breakdown, history, training details) on other multi-agent environments (e.g., PettingZoo MPE).
- Assumptions/dependencies: compute budget for iterative RL; adoption of standardized logging and evaluation metrics.
- Financial stress testing for RL-based trading or decision agents (offline)
- Sector: finance
- Tools/products/workflows:
- Configure simulated market environments (volatility regimes, event shocks, liquidity constraints) based on backtest failure analysis; concentrate next rounds on near-frontier stressors.
- Ops dashboards that show how environment distribution shifts impact drawdowns, risk metrics, and policy robustness.
- Assumptions/dependencies: high-fidelity market simulators with configurable regimes; clear failure taxonomies (e.g., stop-loss breaches, tail-risk events); governance to prevent overfitting to bespoke simulators.
- Logistics and operations optimization simulators
- Sector: supply chain/industrial operations
- Tools/products/workflows:
- Digital twins or job-shop simulators that adjust job arrival processes, resource constraints, and congestion parameters in response to RL agent failures (deadlocks, tardiness).
- “Environment Engineer” service that suggests training mixes to grow performance near the current competence frontier.
- Assumptions/dependencies: parameterizable simulators/digital twins; unambiguous failure labels (e.g., missed deadlines, constraint violations); safety constraints to avoid unrealistic training distributions.
- Cybersecurity cyber ranges
- Sector: cybersecurity
- Tools/products/workflows:
- Adjust attack mixes, lateral movement patterns, and timing distributions based on detection/prevention failures to form the next training batch for detection agents or SOC playbooks.
- Coupling with adversarial ML toolkits and emulated enterprise setups (e.g., CALDERA).
- Assumptions/dependencies: programmatically configurable cyber ranges; reliable mapping between observed misses and scenario knobs; red-team oversight.
- Regulatory sandboxes and audit testbeds for AI agents
- Sector: policy/regulation
- Tools/products/workflows:
- Closed-loop scenario libraries for regulatory sandboxes that respond to observed system failures with targeted next-stage tests, while preserving established “healthy” scenarios.
- Compliance reporting that logs every redesign step and its basis in failure evidence.
- Assumptions/dependencies: agreed-upon failure taxonomies; fixed hold-out evaluations to prevent gaming; transparency and traceability requirements.
Long-Term Applications
- Self-improving foundation model training pipelines (cross-domain)
- Sector: AI infrastructure/ML platforms
- Tools/products/workflows:
- “EnvironmentOps” platforms where LLMs curate and reweight synthetic data sources and task generators across modalities (code, text, reasoning, planning), guided by structured failure breakdowns.
- Mixture-of-tasks schedulers that preserve proven distributions and focus on near-frontier gaps, reducing manual curriculum design at scale.
- Assumptions/dependencies: robust, parameterized data/task generators across domains; strong governance (eval/train separation, anti-reward-hacking measures); scalable logging.
- High-fidelity AV/robotics safety qualification with adaptive scenario libraries
- Sector: automotive, robotics
- Tools/products/workflows:
- End-to-end pipelines that translate fleet/disengagement logs into validated, parameterized scenario families for both training and formal safety tests, automatically adjusting distributions to probe weaknesses without losing learnability.
- Standardized “failure-aware” scenario catalogs used across vendors and regulators.
- Assumptions/dependencies: validated simulators and scenario taxonomies; standards to keep evaluation independent of training; legal/ethical frameworks for sharing failure-derived scenarios.
- Online adaptation for real-world robotic fleets via digital twins
- Sector: warehousing, manufacturing, service robotics
- Tools/products/workflows:
- Closed-loop digital twins where the environment engineer updates simulation curricula from live performance logs, then selectively transfers policies or fine-tuning to the fleet.
- Frontier-aware scheduling of on-robot exploration with strict safety guards.
- Assumptions/dependencies: high-fidelity digital twins; safe sim-to-real transfer protocols; robust safety envelopes to prevent risky on-device exploration.
- Healthcare training and decision-support simulation
- Sector: healthcare/medical education
- Tools/products/workflows:
- Patient-scenario generators that adapt case mixes (comorbidities, demographics, rare conditions) based on model or trainee failures; next-round curricula target diagnostic blind spots without overwhelming.
- For AI-CDS systems, build controlled “training distributions” that pressure-test failure patterns before any clinical deployment.
- Assumptions/dependencies: clinically validated simulators and item banks; IRB/ethics oversight; conservative boundaries that separate evaluation from training; risk management for rare events.
- Energy grid and critical infrastructure control
- Sector: energy/utilities
- Tools/products/workflows:
- Grid-simulation curricula that increase exposure to contingencies (line trips, renewables intermittency, demand spikes) aligned to control-policy failures while avoiding signal collapse.
- Ops platforms that document environment redesign decisions for audit and reliability assurance.
- Assumptions/dependencies: high-fidelity simulators with controllable fault/event parameters; robust failure classification; coordination with reliability standards.
- National security and disaster-response planning
- Sector: public safety/defense
- Tools/products/workflows:
- Multi-agent coordination simulators (evacuation, resource allocation) that progressively target coordination failures; scenario distributions evolve to maintain learnability while probing weak strategies.
- “Evidence-driven” scenario curation for training and evaluation of planning agents.
- Assumptions/dependencies: domain-specific, parameterized simulators; ethical and legal review; strict separation of red-teaming data from deployment-critical evaluation.
- Standardization and policy frameworks for adaptive training distributions
- Sector: policy/regulation
- Tools/products/workflows:
- Standards for failure taxonomies, environment-parameter DSLs, and logs of redesign decisions to improve transparency and reproducibility.
- Certification regimes that mandate independent hold-out testbeds and traceable redesign justifications.
- Assumptions/dependencies: multi-stakeholder consensus on taxonomies and reproducibility; mechanisms to prevent overfitting to evaluation suites.
- Consumer-facing adaptive training experiences
- Sector: consumer apps/games/learning
- Tools/products/workflows:
- Long-term, general-purpose personal tutors or training companions that autonomously adjust task distributions across skills and contexts, preserving mastered areas and focusing on near-frontier challenges.
- Assumptions/dependencies: reliable, privacy-preserving telemetry; pedagogical and UX validation; safeguards against frustration from over-hard curricula.
Notes on feasibility and transfer
- The paper’s gains hinge on (a) controllable generators with exposed parameters, (b) structured, task-grounded failure breakdowns, and (c) stable, independent evaluation sets. In domains lacking these, benefits require building instrumentation, taxonomies, and parameterizable simulators first.
- Evidence-driven edits that preserve working configurations and avoid naïve difficulty monotonicity were key to observed improvements; deployments should monitor for overfitting, collapsed learning signals, and reward hacking.
- The benchmark trains on 2-agent and evaluates on 3–5-agent cases; domain transfers should validate generalization when training-evaluation gaps are larger or when failure signals are noisier.
Glossary
- Adaptive weights: A scheduling scheme that adjusts the relative importance of reward components over training. "Adaptive weights. The two weights are scheduled to shift emphasis from brevity to correctness as the model learns to produce concise outputs."
- AdamW: An optimizer that decouples weight decay from the gradient-based update for better regularization. "We optimize the actor with AdamW at a constant learning rate of 2×10-6"
- Actor: In policy gradient RL, the policy network that outputs actions; optimized directly from rewards. "the actor uses FSDP without offload but with gradient checkpointing."
- Closed-loop framework: A training setup where outputs of one stage inform the configuration of the next, forming a feedback loop. "we propose a closed-loop framework for policy-conditioned environment redesign, which we refer to as an LLM-as-Environment-Engineer."
- Competence frontier: The boundary of task difficulty where the current model begins to struggle but can still learn effectively. "concentrates budget just below the competence frontier"
- Conflict-Based Search: A classic algorithm for solving multi-agent path finding by resolving conflicts between agents’ paths. "We build a environment generator on top of the Conflict-Based Search algorithm."
- Curriculum learning: A strategy that orders or scales task difficulty to improve learning efficiency. "Curriculum learning improves training efficiency by controlling the difficulty or ordering of training experience"
- Data ratio: The share of training instances allocated to each map size in the generator configuration. "rs, the data ratio - the share of training instances sampled at size s"
- Edge conflict: In MAPF, a collision where two agents swap positions along an edge at the same time. "Conflict-free - no vertex or edge conflict;"
- EMA: Exponential Moving Average; a smoothed statistic over recent batches. "Let s denote the EMA of the short-response ratio (fraction of responses with { ≤ L1) across batches."
- Environment engineer: The model (or module) that proposes updates to the environment generator’s configuration based on training feedback. "we condition the environment engineer on structured summaries of policy behavior, failure cases, and environment statistics"
- Environment generator: A parameterized system that produces training instances according to a configuration. "Instead, it modifies the parameters of an environment generator, thereby reshaping the future distribution from which training instances will be sampled."
- Environment redesign: The process of modifying environment parameters to improve learning signals and outcomes. "making it suitable for studying and benchmarking environment redesign."
- FSDP: Fully Sharded Data Parallel; a distributed training technique that shards model parameters across devices. "is kept frozen with FSDP parameter offload; the actor uses FSDP without offload but with gradient checkpointing."
- Gradient checkpointing: A memory-saving technique that recomputes activations during backpropagation to reduce GPU memory usage. "the actor uses FSDP without offload but with gradient checkpointing."
- GRPO: A reinforcement learning algorithm used to optimize policies without a critic in this setup. "using GRPO with the adaptive-weight reward described in §3.1.2."
- Hole ratio: The fraction of grid cells turned into obstacles (holes) for a given map size. "the hole ratio - the fraction of cells turned into holes in maps of size s"
- KL penalty: A regularizer that penalizes divergence between the current policy and a reference policy to stabilize updates. "apply a low-variance KL penalty (B=10-3) directly in the actor loss"
- MAPF-FrozenLake: A controllable testbed combining Multi-Agent Path Finding with FrozenLake-style grid worlds for environment redesign studies. "we design MAPF-FrozenLake, a controllable Multi-Agent Path Finding version of FrozenLake"
- Manhattan distance: A distance metric on grids computed as the sum of absolute coordinate differences. "Legal-move - each step has Manhattan distance ≤ 1;"
- Multi-Agent Path Finding (MAPF): The problem of finding collision-free paths for multiple agents from start to goal on a grid. "a controllable Multi-Agent Path Finding version of FrozenLake"
- Optimal rate: The percentage of instances where the model finds an optimal solution, not just a valid one. "acc. is the valid rate (%) and opt . is the optimal rate (%);"
- Policy-conditioned environment redesign: Adjusting environment parameters based on the current policy’s observed failures and capabilities. "we propose a closed-loop framework for policy-conditioned environment redesign"
- Reference policy: A fixed policy snapshot used to measure divergence or anchor updates during training. "The reference policy is the policy at the start of each round and is kept frozen with FSDP parameter offload"
- Reward hacking: Exploiting the reward function in unintended ways that don’t reflect genuine task improvement. "supports training-aware environment design rather than reward hacking."
- Self-play: A training paradigm where agents learn by interacting with copies or versions of themselves (or other agents). "self-play and multi- agent training frameworks (Fang et al., 2025; Shi et al., 2025; Yuan et al., 2024) adapt the training signal"
- Valid rate: The percentage of instances where outputs meet all validity criteria (e.g., legal, conflict-free, goal-reaching). "acc. is the valid rate (%) and opt . is the optimal rate (%);"
- vLLM: A high-throughput inference engine used here to sample multiple trajectories from the current policy. "for every prompt we sample n=8 trajectories from the current actor with vLLM"
- Vertex conflict: In MAPF, a collision where two agents occupy the same cell at the same time. "Conflict-free - no vertex or edge conflict;"
- Wait action: A MAPF action where an agent stays in place for a time step to avoid conflicts. "a wait action is available for resolving conflicts."
- Wait ratio: The fraction of generated instances that require using at least one wait action to resolve conflicts. "the wait ratio - the fraction of generated instances at size s that require at least one wait action to resolve agent conflicts."
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