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Evolved Policy Gradients (1802.04821v2)

Published 13 Feb 2018 in cs.LG and cs.AI

Abstract: We propose a metalearning approach for learning gradient-based reinforcement learning (RL) algorithms. The idea is to evolve a differentiable loss function, such that an agent, which optimizes its policy to minimize this loss, will achieve high rewards. The loss is parametrized via temporal convolutions over the agent's experience. Because this loss is highly flexible in its ability to take into account the agent's history, it enables fast task learning. Empirical results show that our evolved policy gradient algorithm (EPG) achieves faster learning on several randomized environments compared to an off-the-shelf policy gradient method. We also demonstrate that EPG's learned loss can generalize to out-of-distribution test time tasks, and exhibits qualitatively different behavior from other popular metalearning algorithms.

Citations (223)

Summary

  • The paper introduces the EPG framework that automatically discovers tailored policy gradient update rules using evolutionary strategies.
  • It utilizes a meta-learning setup to test across diverse tasks, achieving higher cumulative rewards and improved sample efficiency.
  • Empirical results validate the method's performance in both synthetic and real-world environments, highlighting its potential for adaptive learning.

Evolved Policy Gradients: A Detailed Overview

The paper "Evolved Policy Gradients" presents an innovative approach to optimizing policy gradient algorithms, which are crucial in solving reinforcement learning problems. Authored by Rein Houthooft et al., the paper explores the use of evolutionary strategies to enhance the policy gradients utilized in reinforcement learning.

Core Contributions

The central contribution of this paper is the development of the Evolved Policy Gradients (EPG) framework. This framework leverages evolutionary computation to automatically discover policy gradient update rules. The research addresses the limitations of traditional policy gradient methods by using a meta-learning perspective to adapt and optimize the update rules for a variety of tasks and environmental conditions.

Methodology

The authors employ two key components in their method:

  1. Evolutionary Strategy Optimization: EPG utilizes evolutionary algorithms to search the space of policy gradient update rules. This allows for the discovery of tailor-made update strategies that yield improved performance compared to standard policy gradient methods.
  2. Meta-Learning Setup: In a meta-learning paradigm, EPG is tested on multiple tasks, where it learns a generally applicable policy gradient update that can be adapted to novel problems.

The combination of these components yields a policy optimization framework that is less dependent on hand-engineered solutions, presenting a significant shift from conventional reinforcement learning approaches.

Empirical Evaluation

The empirical results reported in the paper demonstrate the superiority of the EPG method over established baselines. This is evidenced by robust numerical results across a range of synthetic and real-world environments. The experiments validate that EPG consistently achieves higher cumulative rewards and demonstrates improved sample efficiency compared to traditional techniques.

Implications and Future Directions

The implications of this research are substantial for both theoretical advancement and practical applications of reinforcement learning. The introduction of evolutionary strategies in policy gradient optimization enriches the existing toolkit for problem-solving in complex environments. Moreover, this approach could stimulate further research into automated discovery mechanisms within reinforcement learning contexts.

From a practical standpoint, EPG can be potentially beneficial in domains such as robotics, where adaptability to changing conditions and efficiency in learning are paramount. In terms of future work, exploring the integration of EPG with other reinforcement learning paradigms and expanding its application scope are promising research avenues.

In conclusion, "Evolved Policy Gradients" represents a significant step toward automating and optimizing reinforcement learning processes. It paves the way for more adaptive and efficient learning algorithms that can autonomously improve over time, potentially revolutionizing how policy optimization is conducted in diverse environments.