| Summary: | Event Structures (ESs) address the representation of direct relationships
between individual events, usually capturing the notions of causality and
conflict. Up to now, 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 dynamic by allowing causal dependencies between some
events to be changed by occurrences of other events. We first model and study
the case in which events may entail the removal of causal dependencies, then we
consider the addition of causal dependencies, and finally we combine both
approaches in the so-called Dynamic Causality ESs. For all three newly defined
types of ESs, we study their expressive power in comparison to the well-known
Prime ESs, Dual ESs, Extended Bundle ESs, and ESs for Resolvable Conflicts.
Interestingly, Dynamic Causality ESs subsume Extended Bundle ESs and Dual ESs
but are incomparable with ESs for Resolvable Conflicts.
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