  Policy enforcers are sophisticated runtime components that can prevent
failures by enforcing the correct behavior of the software. While a single
enforcer can be easily designed focusing only on the behavior of the
application that must be monitored, the effect of multiple enforcers that
enforce different policies might be hard to predict. So far, mechanisms to
resolve interferences between enforcers have been based on priority mechanisms
and heuristics. Although these methods provide a mechanism to take decisions
when multiple enforcers try to affect the execution at a same time, they do not
guarantee the lack of interference on the global behavior of the system. In
this paper we present a verification strategy that can be exploited to discover
interferences between sets of enforcers and thus safely identify a-priori the
enforcers that can co-exist at run-time. In our evaluation, we experimented our
verification method with several policy enforcers for Android and discovered
some incompatibilities.
