Abstract: Advances in Reinforcement Learning (RL) have successfully tackled sample efficiency and overestimation bias. However, these methods often fall short of scalable performance. On the other hand, genetic methods provide scalability but depict hyperparameter sensitivity to evolutionary operations. We present the Evolution-based Soft Actor-Critic (ESAC), a scalable RL algorithm. Our contributions are threefold; ESAC (1) abstracts exploration from exploitation by combining Evolution Strategies (ES) with Soft Actor-Critic (SAC), (2) provides dominant skill transfer between offsprings by making use of soft winner selections and genetic crossovers in hindsight and (3) improves hyperparameter sensitivity in evolutions using Automatic Mutation Tuning (AMT). AMT gradually replaces the entropy framework of SAC allowing the population to succeed at the task while acting as randomly as possible, without making use of backpropagation updates. On a range of challenging robot control tasks consisting of high-dimensional action spaces and sparse rewards, ESAC demonstrates improved performance and sample efficiency in comparison to the Maximum Entropy framework. ESAC demonstrates scalability comparable to ES on the basis of hardware resources and algorithm overhead. A complete implementation of ESAC with notes on reproducibility and videos can be found at the project website https://karush17.github.io/esac-web/.

Keywords: ESAC, mutation, AMT, policy

Abstract: Multi-Agent Reinforcement Learning (MARL) has demonstrated significant success in training decentralised policies in a centralised manner by making use of value factorization methods. However, addressing surprise across spurious states and approximation bias remain open problems for multi-agent settings. We introduce the Energy-based MIXer (EMIX), an algorithm which minimizes surprise utilizing the energy across agents. Our contributions are threefold; (1) EMIX introduces a novel surprise minimization technique across multiple agents in the case of multi-agent partially-observable settings. (2) EMIX highlights the first practical use of energy functions in MARL (to our knowledge) with theoretical guarantees and experiment validations of the energy operator. Lastly, (3) EMIX presents a novel technique for addressing overestimation bias across agents in MARL. When evaluated on a range of challenging StarCraft II micromanagement scenarios, EMIX demonstrates consistent state-of-the-art performance for multiagent surprise minimization. Moreover, our ablation study highlights the necessity of the energy-based scheme and the need for elimination of overestimation bias in MARL. Our implementation of EMIX, videos of agents and blog are available in the supplementary material.