Learning Verified Monitors for Hidden Markov Models

Fuente: arXiv
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Main Authors: van der Maas, Luko, Junges, Sebastian
Format: Preprint
Published: 2025
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author van der Maas, Luko
Junges, Sebastian
author_facet van der Maas, Luko
Junges, Sebastian
contents Runtime monitors assess whether a system is in an unsafe state based on a stream of observations. We study the problem where the system is subject to probabilistic uncertainty and described by a hidden Markov model. A stream of observations is then unsafe if the probability of being in an unsafe state is above a threshold. A correct monitor recognizes the set of unsafe observations. The key contribution of this paper is the first correct-by-construction synthesis method for such monitors, represented as finite automata. The contribution combines four ingredients: First, we establish the coNP-hardness of checking whether an automaton is a correct monitor, i.e., a monitor without misclassifications. Second, we provide a reduction that reformulates the search for misclassifications into a standard probabilistic system synthesis problem. Third, we integrate the verification routine into an active automata learning routine to synthesize correct monitors. Fourth, we provide a prototypical implementation that shows the feasibility and limitations of the approach on a series of benchmarks.
format Preprint
id arxiv_https___arxiv_org_abs_2504_05963
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Learning Verified Monitors for Hidden Markov Models
van der Maas, Luko
Junges, Sebastian
Formal Languages and Automata Theory
Logic in Computer Science
Runtime monitors assess whether a system is in an unsafe state based on a stream of observations. We study the problem where the system is subject to probabilistic uncertainty and described by a hidden Markov model. A stream of observations is then unsafe if the probability of being in an unsafe state is above a threshold. A correct monitor recognizes the set of unsafe observations. The key contribution of this paper is the first correct-by-construction synthesis method for such monitors, represented as finite automata. The contribution combines four ingredients: First, we establish the coNP-hardness of checking whether an automaton is a correct monitor, i.e., a monitor without misclassifications. Second, we provide a reduction that reformulates the search for misclassifications into a standard probabilistic system synthesis problem. Third, we integrate the verification routine into an active automata learning routine to synthesize correct monitors. Fourth, we provide a prototypical implementation that shows the feasibility and limitations of the approach on a series of benchmarks.
title Learning Verified Monitors for Hidden Markov Models
topic Formal Languages and Automata Theory
Logic in Computer Science
url https://arxiv.org/abs/2504.05963