  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. We study the
enforceability of Hennessy-Milner Logic with Recursion (muHML) with respect to
suppression enforcement. We develop an operational framework for enforcement
which we then use to formalise when a monitor enforces a muHML property. We
also show that the safety syntactic fragment of the logic, sHML, is enforceable
by providing an automated synthesis function that generates correct suppression
monitors from sHML formulas.
