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Scalable hierarchical evolution strategies

Hierarchical reinforcement learning (HRL) has been steadily growing in popularity for solving the hardest reinforcement learning problems. However, current HRL algorithms are relatively slow and brittle to hyperparameter changes. This paper offers a solution to these slow and brittle HRL algorithms,...

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Main Author: Abramowitz, Sasha
Other Authors: Nitschke, Geoff
Format: Thesis
Language:English
Published: Department of Computer Science 2023
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access_status_str Open Access
author Abramowitz, Sasha
author2 Nitschke, Geoff
author_browse Abramowitz, Sasha
Nitschke, Geoff
author_facet Nitschke, Geoff
Abramowitz, Sasha
author_sort Abramowitz, Sasha
collection Thesis
description Hierarchical reinforcement learning (HRL) has been steadily growing in popularity for solving the hardest reinforcement learning problems. However, current HRL algorithms are relatively slow and brittle to hyperparameter changes. This paper offers a solution to these slow and brittle HRL algorithms, by investigating a novel method combining Scalable Evolution Strategies (SES) and HRL. S-ES, named for its excellent scalability, was popularised by Open AI when they showed its performance to be comparable to state-of-the art policy gradient methods. However, S-ES has not been tested in conjunction with HRL methods, which empower temporal abstraction thus allowing agents to tackle more challenging problems. We introduce a novel method merging S-ES and HRL, which creates a highly scalable and fast (wall-clock time) algorithm. We demonstrate that S-ES needs no hyper-parameter tuning for the HRL tasks tested and is indifferent to delayed rewards. This results in a method that is significantly faster than gradient-based HRL methods while having competitive task performance. We extend this method using transfer learning with the aim of increasing task performance and novelty search with the goal of improving its exploration characteristics. The paper's main contribution is thus a novel evolutionary HRL method, namely Scalable Hierarchical Evolution Strategies, which yields greater learning speed and competitive task-performance compared to state-of-the-art gradient-based methods, across a range of tasks.
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license_str Not specified — see source repository
provenance_str_mv Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository
publishDate 2023
publishDateRange 2023
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spelling oai:open.uct.ac.za:11427/36999 Scalable hierarchical evolution strategies Abramowitz, Sasha Nitschke, Geoff Computer Science Hierarchical reinforcement learning (HRL) has been steadily growing in popularity for solving the hardest reinforcement learning problems. However, current HRL algorithms are relatively slow and brittle to hyperparameter changes. This paper offers a solution to these slow and brittle HRL algorithms, by investigating a novel method combining Scalable Evolution Strategies (SES) and HRL. S-ES, named for its excellent scalability, was popularised by Open AI when they showed its performance to be comparable to state-of-the art policy gradient methods. However, S-ES has not been tested in conjunction with HRL methods, which empower temporal abstraction thus allowing agents to tackle more challenging problems. We introduce a novel method merging S-ES and HRL, which creates a highly scalable and fast (wall-clock time) algorithm. We demonstrate that S-ES needs no hyper-parameter tuning for the HRL tasks tested and is indifferent to delayed rewards. This results in a method that is significantly faster than gradient-based HRL methods while having competitive task performance. We extend this method using transfer learning with the aim of increasing task performance and novelty search with the goal of improving its exploration characteristics. The paper's main contribution is thus a novel evolutionary HRL method, namely Scalable Hierarchical Evolution Strategies, which yields greater learning speed and competitive task-performance compared to state-of-the-art gradient-based methods, across a range of tasks. 2023-02-23T08:43:16Z 2023-02-23T08:43:16Z 2022 2023-02-20T12:09:06Z Master Thesis Masters MSc http://hdl.handle.net/11427/36999 eng application/pdf Department of Computer Science Faculty of Science
spellingShingle Computer Science
Abramowitz, Sasha
Scalable hierarchical evolution strategies
thesis_degree_str Master's
title Scalable hierarchical evolution strategies
title_full Scalable hierarchical evolution strategies
title_fullStr Scalable hierarchical evolution strategies
title_full_unstemmed Scalable hierarchical evolution strategies
title_short Scalable hierarchical evolution strategies
title_sort scalable hierarchical evolution strategies
topic Computer Science
url http://hdl.handle.net/11427/36999
work_keys_str_mv AT abramowitzsasha scalablehierarchicalevolutionstrategies