Querying nested graphs

At ISWC we - James (Anderson, from Datagraph/Dydra), Olaf and me - had a discussion about query semantics of the nested graph approach and Olaf was kind enough to provide a formalization as a means to better understand where the approach is headed  towards. That is not to be misinterpreted as him endorsing the nested graph proposal. 

His formalization is very succinct and provides a good basis for further discussion. He illustrates a problem with basic graph patterns being returned multiple times when they occur in inner nested graphs (once for each nesting graph). We have some ideas about how to extend the formalization to manage this issue, but before going into further detail I’m attaching here Olaf’s formalization for the WG to check out.

Best,
Thomas