- From: Andy Seaborne <andy@apache.org>
- Date: Thu, 9 Dec 2021 12:50:08 +0000
- To: Pierre-Antoine Champin <pierre-antoine.champin@ercim.eu>, public-rdf-star@w3.org
On 09/12/2021 11:32, Pierre-Antoine Champin wrote: > > On 09/12/2021 12:23, Andy Seaborne wrote: >> >> >> On 08/12/2021 08:07, Pierre-Antoine Champin wrote: >>> >>> On 07/12/2021 22:25, Peter Patel-Schneider wrote: >>>> On Tue, 2021-12-07 at 14:52 +0100, Pierre-Antoine Champin wrote: >>>>> In LPGs as well, there is a point were modelling marriages or pipes >>>>> as edges will hit a wall. More specifically, if you want to relate >>>>> them to other *nodes* of the graph (link a marriage to its location, >>>>> link a pipe to its manufacturer), you also need to reifiy them as >>>>> nodes. >>>> I see some formulations of property graphs where edges can only be >>>> related to values, but is that really the case for all property graphs? >>> >>> I have never seen an explicit definition of "Property Graphs" where >>> this was not the case (but I have not seen them all, of course). >>> >>> I also have the feeling that allowing nodes as property values would >>> pervert the idea of PGs, where the distinction between the internal >>> structure of nodes (properties) and relation with other nodes (edges) >>> is considered an important feature. >> >> >> Looking at some of the JSON serializations at property graphs - they >> don't allow for edges to be nodes. >> >> There are two styles: >> >> * Nodes have integer ids, and edges are represented by start-end id >> pairs and a label. >> >> * Edges have ids but the numbering of nodes and edges starts >> separately at 0 so there are different numbering spaces. >> >> Both cases mean only attributes on edges. > > The way I read Peter's question was : are there PG implementation in > which properties (I assume that's what you mean by "attributes") have > nodes as their value? >>>> where edges can only be related to values I haven't found any serializations that put nodes or edge ids in the data model. The serializations have values that are strings and numbers (JSON-centric). Nothing else. Which formalizations have a type system for values? Andy > >> >> Andy >> >>> >>>> (Well, if you think of Wikibase as a property graph formulation then >>>> there is at least one counterexample.) >>> >>> It never occurred to me to put Wikibase in the "Property Graph" >>> family. I see some similarities, but also many differences. In >>> particular, the distinction I mentioned above (between "properties" >>> and "edges" of a node, in PG parlance) does not exist in Wikibase, >>> where there all represented as "statements" (except for labels and >>> descriptions... but I hope you see my point). >>> >>> pa >>> >>>> >>>> peter >>>> >>>> >>
Received on Thursday, 9 December 2021 12:50:23 UTC