Taming Multi-Agent Reinforcement Learning with Estimator Variance Reduction
Bibliographic record
Abstract
Multi-agent reinforcement learning (MARL) enables systems of autonomous agents to solve complex tasks from jointly gathered experiences of the environment. Many MARL algorithms perform centralised training (CT), often in a simulated environment, where at each time-step the critic makes use of a single sample of the agents' joint-action for training. Yet, as agents update their policies during training, these single samples may poorly represent the agents' joint-policy leading to high variance gradient estimates that hinder learning. In this paper, we examine the effect on MARL estimators of allowing the number of joint-action samples taken at each time-step to be greater than 1 in training. Our theoretical analysis shows that even modestly increasing the number of joint-action samples shown to the critic leads to TD updates that closely approximate the true expected value under the current joint-policy. In particular, we prove this reduces variance in value estimates similar to that of decentralised training while maintaining the learning benefits of CT. We describe how such a protocol can be seamlessly realised by sharing policy parameters between the agents during training and apply the technique to induce lower variance in estimates in MARL methods within a general apparatus which we call Performance Enhancing Reinforcement Learning Apparatus (PERLA). Lastly, we demonstrate PERLA's performance improvements and estimator variance reduction capabilities in a range of environments including Multi-agent Mujoco, and StarCraft II.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.005 | 0.019 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".