Pure-Past Action Masking

Giovanni Varricchione*, Natasha Alechina, Mehdi Dastani, Giuseppe De Giacomo, Brian Logan, Giuseppe Perelli

*Corresponding author for this work

Research output: Contribution to journalConference articleAcademicpeer-review

Abstract

We present Pure-Past Action Masking (PPAM), a lightweight approach to action masking for safe reinforcement learning. In PPAM, actions are disallowed (“masked”) according to specifications expressed in Pure-Past Linear Temporal Logic (PPLTL). PPAM can enforce non-Markovian constraints, i.e., constraints based on the history of the system, rather than just the current state of the (possibly hidden) MDP. The features used in the safety constraint need not be the same as those used by the learning agent, allowing a clear separation of concerns between the safety constraints and reward specifications of the (learning) agent. We prove formally that an agent trained with PPAM can learn any optimal policy that satisfies the safety constraints, and that they are as expressive as shields, another approach to enforce non-Markovian constraints in RL. Finally, we provide empirical results showing how PPAM can guarantee constraint satisfaction in practice.
Original languageEnglish
Pages (from-to)21646-21655
Number of pages10
JournalProceedings of the AAAI Conference on Artificial Intelligence
Volume38
Issue number19
DOIs
Publication statusPublished - 24 Mar 2024

Bibliographical note

Publisher Copyright:
Copyright © 2024, Association for the Advancement of Artificial Intelligence (www.aaai.org). All rights reserved.

Funding

This work was supported by PNRR MUR project PE0000013-FAIR, partially supported by ERC Advanced Grant WhiteMech (No. 834228), EU ICT-48 2020 project TAILOR (No. 952215), the ONRG project N62909-22-1-2005, the InDAM-GNCS project \u201CStrategic Reasoning in Mechanism Design\u201D, and the project OCENW.M.21.377 funded by the Dutch Research Council (NWO). For the purpose of open access, the authors have applied a Creative Commons Attribution (CC BY) licence to any Author Accepted Manuscript version arising from this submission.

FundersFunder number
Nederlandse Organisatie voor Wetenschappelijk Onderzoek
PNRRPE0000013-FAIR
European Research Council834228
EU ICT-48 2020952215, N62909-22-1-2005

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