- From: Jeen Broekstra <jb@metaphacts.com>
- Date: Wed, 3 Mar 2021 10:21:03 +1100
- Cc: public-rdf-star@w3.org
- Message-ID: <CAD8Bno9FjjO_m8Kc-T=iJq4TBeFFNULxPKq8E9=aVOUsE9GZCQ@mail.gmail.com>
On Wed, 3 Mar 2021 at 08:57, James Anderson <anderson.james.1955@gmail.com> wrote: > > > On 2021-03-02, at 21:34:20, Gregg Kellogg <gregg@greggkellogg.net> > wrote: > > > >> On Mar 2, 2021, at 12:09 PM, James Anderson < > anderson.james.1955@gmail.com> wrote: > >> > >> good evening; > >> > >>> On 2021-03-02, at 18:56:40, Olaf Hartig <olaf.hartig@liu.se> wrote: > >>> > >>> ... > >>> > >>> The changes are in Section 4.2 (SPARQL-star Grammar) and in the new > Section > >>> 4.4 (Function Definitions). > >>> > >>> As agreed during our telco last Friday, I will leave this PR open for > three > >>> days so that your can take a look at it and raise concerns (if any). > Unless > >>> anyone brings forward reasons that this PR should not be merged, I > will merge > >>> it on Friday afternoon (CET). > >> > >> i raise the concern, that the approach needs to comprehend quads before > it will be usable. > > > > I think this comment is more general than the specific functions added. > It would be useful to have some examples that use various combinations of > embedded triples, annotations, and these functions within named graphs. > > it would also be useful to know the consequences for paragraph 15.1 and > section 17 of the sparql recommendation. > In the interest of saving everybody's time trying to puzzle out what these sections are about and how it relates to the topic under discussion, I have done some homework. I'll ignore the earlier remark about quads because I have no clue what is intended there or how it fits in with the topic under discussion (the new functions). Section 15.1 is about establishing a partial ordering of RDF values for the purpose of executing an ORDER BY clause. See https://www.w3.org/TR/sparql11-query/#solutionModifiers <https://www.w3.org/TR/sparql11-query/#solutionModifiers> . Although it has no direct bearing on the introduction of these new functions, there is a valid point here that we'll need to establish how RDF-star triples fit into that partial ordering. For what it's worth, RDF4J has extended the partial ordering by adding RDF-star triples at the end (behind RDF literals), and by comparing two RDF-star triples by first comparing subject, then predicate, then object to establish order. Section 17 is about expressions and value testing. See https://www.w3.org/TR/sparql11-query/#expressions. What I'm *guessing *mr. Anderson is referring to as needing examination is the notion of RDFterm-equality (see https://www.w3.org/TR/sparql11-query/#func-RDFterm-equal). In particular, it will need extending to explicitly state that two terms are considered RDFterm-equal if they are both RDF-star triples and those triples are equivalent under our predefined notion of equivalence (which I assume would be most simply expressed in terms of each of its constuent parts being RDFterm-equal, cf. https://w3c.github.io/rdf-star/cg-spec/2021-02-18.html#dfn-rdf-star-terms). Regards, Jeen -- Dr Jeen Broekstra (he, him) *principal software engineer* jb@metaphacts.com www.metaphacts.com [image: htps://www.metaphacts.com/] <https://www.metaphacts.com/>
Received on Tuesday, 2 March 2021 23:21:28 UTC