A Representation of DI

Abstract

We know from the previous chapter that dl-domains can be represented as stable event structures. It may have been observed by the reader that there is some similarity between event structures and information systems. The difference is, however, perhaps bigger than the similarity after a second thought. For an information system, for example, if X ⊢ a and X ⊢ a’ then a and a’ must be consistent while for an event structure, we cannot say anything about the consistency of two events e, e’ enabled by the same set of events. This reflects the fact that for information systems h stands for logical entailment between propositions whereas in the case of event structures it expresses sufficient conditions for an event to occur due to the previous occurrences of other events. Thus information systems capture the logical relations between facts about a computation while event structures capture their temporal relationship.