On first-order runtime enforcement of branching-time properties

Abstract

Runtime enforcement is a dynamic analysis technique that uses monitors to enforce the behaviour specified by some correctness property on an executing system. The enforceability of a logic captures the extent to which the properties expressible via the logic can be enforced at runtime for a specified operational model of enforcing monitors. We study the enforceability of branching-time, first-order properties expressed in the Hennessy–Milner Logic with Recursion (\(\mu \) HML) with respect to monitors that can enforce behaviour involving events that carry data. To this end, we develop an operational framework for first-order enforcement via suppressions, insertions and replacements. We then use this model to formalise the meaning of enforcing a branching-time property. We also show that a safety syntactic fragment of the logic is enforceable within this framework by providing an automated synthesis function that generates correct suppression monitors from any formula taken from this logical fragment.