- From: Pierre-Antoine Champin <pierre-antoine.champin@ercim.eu>
- Date: Wed, 10 Mar 2021 09:50:26 +0100
- To: "public-rdf-star@w3.org" <public-rdf-star@w3.org>
- Message-ID: <7fe51d48-1925-747c-99b1-b9ca74581474@ercim.eu>
Update on this new semantics proposal: I re-introduced one hidden IRI, for the same reason as before (RDF-star systems should not be required to "compile" descriptions of embedded triples into proper embeded triples). Unlike its predecessors, however, that IRI /can/ hide from SPARQL (see issue #101 <https://github.com/w3c/rdf-star/issues/101>) because it is not entailed by the embedded triple. pa On 05/03/2021 19:02, Pierre-Antoine Champin wrote: > > I forgot to put the link to the preview, for those not quite familiar > with our github: > > https://pr-preview.s3.amazonaws.com/w3c/rdf-star/pull/127.html#rdf-star-semantics > > On 05/03/2021 19:00, Pierre-Antoine Champin wrote: >> >> Hi all, >> >> I just pushed a pull-request adapting the semantics: >> >> https://github.com/w3c/rdf-star/pull/127 >> >> I believe it has some advantages over the current version: >> >> * it does not rely anymore on "hidden" predicates (see issue #101 >> <https://github.com/w3c/rdf-star/issues/101>) >> * it does not have the "merging" issue warned about in ยง6.3.1 >> <https://w3c.github.io/rdf-star/cg-spec/2021-02-18.html#combining-rdf-star-graphs> >> * I think that it allows us to align SPARQL query semantics with >> simple entailment (as newly defined) >> * I think that it allows the Interpolation Lemma >> <https://www.w3.org/TR/rdf11-mt/#dfn-interpolation> to extend to >> RDF-star >> >> (I didn't formally prove the last two items, hence "I think"...) >> >> The trick is that we do not map anymore RDF-star graphs to a single, >> semantically equivalent RDF graph. >> Instead, we map it to a pair of RDF graphs, which can be thought of >> as a "lower and upper bound" of the RDF-star graph, in terms of >> entailment. The semantics of the RDF-star graph is defined through >> the semantics of its "bounds", reusing RDF semantics as is (as we >> currently do). >> >> In this new semantics, a strict RDF-star graph (i.e. one that >> contains embedded triples) has no exactly equivalent RDF graph, so it >> still can not be conveyed exactly using RDF syntaxes (but we do not >> rely anymore on hidden predicates for that). However, either of the >> two "bounds" can be used to approximate the RDF-star graph in legacy >> RDF. The "lower bound" will produce correct but incomplete >> inferences. The "upper bound" will produce complete inferences, with >> a few spurious (but generally harmless) ones. >> >> I am curious to get some feedback on this. >> >>
Received on Wednesday, 10 March 2021 08:50:31 UTC