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RDF-star specification
https://w3c.github.io/rdf-star/
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alternative semantic characterisations for RDF* #95

Open pfps opened 3 years ago

pfps commented 3 years ago

There are several resent proposals for semantics.

The proposals can be found in 1/ https://github.com/w3c/rdf-star/pull/81 2/ https://github.com/w3c/rdf-star/pull/88 3/ https://lists.w3.org/Archives/Public/public-rdf-star/2021Jan/0057.html 4/ https://lists.w3.org/Archives/Public/public-rdf-star/2021Jan/0059.html 5/ https://lists.w3.org/Archives/Public/public-rdf-star/2021Feb/0038.html and 6/ https://github.com/w3c/rdf-star/pull/127

All proposals create RDF graphs and the semantics of RDF* is defined as a semantics for these RDF graphs.

The differences between them lie in four areas: A) RDF graphs as an abstract syntax B) hidden vocabulary for RDF reification C) special datatype(s) for embedded triples D) extended semantics for RDF* reification vocabulary

First, there is whether there is the notion of an RDF graph. RDF surface syntax can be expressed by parsing RDF surface syntax into RDF graphs and then transforming these RDF graphs into RDF graphs. Alternatively, RDF surface syntax can be expressed by parsing surface syntax directly into RDF graphs.

Second, there is whether the vocabulary used to reify embedded triples is hidden or not. If so, then RDF* embedded triples cannot be constructed by means other than embedded triple syntax. If not, then regular RDF constructs (almost certainly reification) can be used to get the same effect as embedded triples.

Third, there is whether one or more special datatypes are needed for the subject, predicate, or object of embedded triples.

Fourth, there is whether the semantics of RDF* needs an extension of RDF semantics on the resultant RDF graphs (aside from the semantics of any new datatypes).

Here is a table of my understanding of how the proposals stand on the above differences.

Characteristic 1/ #81 2/ #88 3/ link 4/ link 5/ link 6/ #127
A) RDF* graphs YES YES YES YES NO YES
B) hidden vocabulary YES YES NO NO NO YES(1)
C) special datatype(s) YES NO YES NO NO NO
D) extended semantics YES NO NO NO NO NO

(1) #127 reuses and extends the standard reification vocabulary, but uses a hidden type for embedded triples

edited on 2021-03-10 by @pchampin add PR #127

pchampin commented 3 years ago

See also #101 regarding the consequences of B) hidden vocabulary