Ain't No Stopping Us Monitoring Now

TL;DR

This paper explores the concept of monitorability in runtime verification, demonstrating how non-monitorable properties can still be partially verified, with theoretical insights and application to Linear Temporal Logic.

Contribution

It provides a semantic-level analysis of monitorability and introduces methods for partial verification of non-monitorable properties, especially in LTL.

Findings

Non-monitorable properties can be partially verified.

Theoretical framework for monitorability at a semantic level.

Application of theory to Linear Temporal Logic.

Abstract

Not all properties are monitorable. This is a well-known fact, and it means there exist properties that cannot be fully verified at runtime. However, given a non-monitorable property, a monitor can still be synthesised, but it could end up in a state where no verdict will ever be concluded on the satisfaction (resp., violation) of the property. For this reason, non-monitorable properties are usually discarded. In this paper, we carry out an in-depth analysis on monitorability, and how non-monitorable properties can still be partially verified. We present our theoretical results at a semantic level, without focusing on a specific formalism. Then, we show how our theory can be applied to achieve partial runtime verification of Linear Temporal Logic (LTL).