Semantics of an NIS
NIS contains several gestalts, and graphs of gestalts.
- Potentially, even cycles: Gestalt A is registered as a source in Gestalt B, and B is also registered as a source in A.
In the presence of cycles, what is the semantics of a gestalt table definition?
- Fixpoint semantics: Impractical, because definition of view as well as query evaluation is highly distributed.