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Re: RDF-star vs Wikidata for modelling Richard Burton

From: Pierre-Antoine Champin <pierre-antoine.champin@ercim.eu>
Date: Thu, 9 Dec 2021 12:32:01 +0100
Message-ID: <f84a4af8-0a85-9f87-5d39-a316f371ea0a@ercim.eu>
To: Andy Seaborne <andy@apache.org>, public-rdf-star@w3.org

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?

>
>     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 11:32:04 UTC

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