Re: labelled property graphs vs -star extension of RDFn vs -star extension of named graphs

> On 8. Dec 2023, at 15:18, Peter F. Patel-Schneider <pfpschneider@gmail.com> wrote:
> 
> At the teleconference yesterday I mentioned that there could be user-visible differences between different views of how to proceed, even when there is some consensus that different views are essentially the same.
> 
> Here is one example of a user-visible divergence.  Consider the following input, written in the community group syntax.
> 
> :liz :spouse :dick {| :start 1964; :end 1974 |} .
> :liz :spouse :dick {| :start 1975; :end 1976 |} .
> 
> In the community graph version of RDF-star this results in one asserted triple with subject :liz that is the subject of four triples.  In SPARQL-star, the BGP
> 
> :liz :spouse :dick {| :start 1964; :end 1976 |} .
> 
> would match against a graph constructed from this input.
> 
> In labelled property graphs this would appear to result in two asserted triples with subject :liz, each with two property-value pairs.  The above BGP would not match.
> 
> So there is a decided visible difference between the community graph version of RDF-star and labelled property graphs.

Yes. I believe a proposal has somewhere, somewhen (by me) been made that the shorthand syntax be extended by an identifier, e.g.

    :liz :spouse :dick { id:1 | :start 1964; :end 1974 |} .
    :liz :spouse :dick { id:2 | :start 1975; :end 1976 |} .

which would map to 

    id:1 rdfx:occurrenceOf << :liz :spouse :dick >> ;
         :start 1964; :end 1974 .

    id:2 rdfx:occurrenceOf << :liz :spouse :dick >> ;
         :start 1975; :end 1976 .

> If I am correct in reading the (sparse) information available about RDFn, a -star extension of RDFn would conform to the community group reading.  

My reading is that two occurrences get two different identifiers. The identifiers are not a function of the triple alone. Anyway, even if it isn’t yet it seems that that would be easy to add.

> So there would be noticeable differences between an extended RDFn and labelled property graphs.
> 
> I am not aware of any proposal for using named graphs that says what the above would result in there, so it is unclear which side a named graphs version of -star would fit into.

The nested named graph proposal is very definite about this, and it is clearly in the multi-edge camp

Thomas

> peter
>

Received on Friday, 8 December 2023 14:48:25 UTC