Dynamic Causality in Event Structures

Event Structures (ESs) address the representation of direct relationshipsbetween individual events, usually capturing the notions of causality and conflict. Up tonow, such relationships have been static, i.e. they cannot change during a system run.Thus, the common ESs only model a static view on systems. We make causality dynamicby allowing causal dependencies between some events to be changed by occurrences ofother events. We first model and study the case in which events may entail the removalof causal dependencies, then we consider the addition of causal dependencies, and finallywe combine both approaches in the so-called Dynamic Causality ESs. For all three newlydefined types of ESs, we study their expressive power in comparison to the well-knownPrime ESs, Dual ESs, Extended Bundle ESs, and ESs for Resolvable Conflicts. Interestingly,Dynamic Causality ESs subsume Extended Bundle ESs and Dual ESs but are incomparablewith ESs for Resolvable Conflicts.