Reinforcement learning algorithms discover policies that maximize reward. However, these policies generally do not adhere to safety, leaving safety in reinforcement learning (and in artificial intelligence in general) an open research problem. Shield synthesis is a formal approach to synthesize a correct-by-construction reactive system called a shield that enforces safety properties of a running system while interfering with its operation as little as possible. A shield attached to a learning agent guarantees safety during learning and execution phases. In this paper we summarize three types of shields that are synthesized from different specification languages, and discuss their applicability to reinforcement learning. First, we discuss deterministic shields that enforce specifications expressed as linear temporal logic specifications. Second, we discuss the synthesis of probabilistic shields from specifications in probabilistic temporal logic. Third, we discuss how to synthesize timed shields from timed automata specifications. This paper summarizes the application areas, advantages, disadvantages and synthesis approaches for the three types of shields and gives an overview of experimental results.
|Title of host publication||Leveraging Applications of Formal Methods, Verification and Validation : Verification Principles - 9th International Symposium on Leveraging Applications of Formal Methods, ISoLA 2020, Proceedings|
|Editors||Tiziana Margaria, Bernhard Steffen|
|Number of pages||17|
|Publisher||Springer Science+Business Media|
|Publication status||Published - 2020|
|Event||9th International Symposium on Leveraging Applications of Formal Methods, Verification and Validation, ISoLA 2020 - Rhodes, Greece|
Duration: 20 Oct 2020 → 30 Oct 2020
|Conference||9th International Symposium on Leveraging Applications of Formal Methods, Verification and Validation, ISoLA 2020|
|Period||20/10/2020 → 30/10/2020|
|Series||Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)|
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