W3C

– DRAFT –
RDF-star Semantics TF

07 June 2024

Attendees

Present
AndyS, enrico, gkellogg, niklasl, pchampin, pfps, Souri, TallTed, tl
Regrets
-
Chair
?chair?
Scribe
?scribe?

Meeting minutes

<niklasl> Are we clear about when we talk about bnode symbols in a graph and when we talk about bnode labels in an RDF source?

<niklasl> CDT: https://awslabs.github.io/SPARQL-CDTs/spec/latest.html

<Souri> Are the two references to _:b1 in the following example denote the same bnode? ==> _:b1 :p1 :o1 . :r1 rdf:annotationOf <<(' _:b1 :p2 :o2 ')>> .

<niklasl> We don't know yet. If completely opaque; then no.

<pchampin> _:b :smurfs :t.

<pchampin> _:c :smurfs :t.

<pchampin> :t rdf:annotationOf <<' :alice :likes _:b '>>.

<AndyS> Add _:c rdfs:label "fred" .

<niklasl> :t ex:ref _:b . # ?

<enrico> I agree that the current semantics of opaque triple terms leads to this confusion.

<enrico> So, we should conclude that we need that bnodes are transparent within opaque triple terms

<niklasl> +1 to TallTed!

<enrico> +1 to TallTed!

<Souri> Would this set of annotations constitute a two-edge multi-edge (set of two parallel edges)? => :r1 rdf:annotationOf <<' _:b1 :p :o '>> . :r2 rdf:annotationOf <<' _:b1 :p :o '>> .

<AndyS> Yes (I hope!) - old speak "two occurrences, two uses of the concept of the triple _:b1 :p :o."

<Souri> I hope so too because that is the only way we can have multi-edge where parallel edges can use blank node(s) as subject and/or object.

<niklasl> ... require triple literals, when fully written out, to use skolemized forms?

<TallTed> quoting is different from paraphrasing

<pchampin> but then if they used bnodes, you can't possibly use the same "word" that they used

<Souri> Just to confirm: Can this be used to represent a path from alice to bob with annotated edges? => :r1 rdf:annotationOf <<' :alice :knows _:b '>> . :r2 rdf:annotationOf <<' _:b :knows :bob '>> . :r1 :linkNum 1 ; :cost 100 . :r2 :linkNum 2 ; :cost 200 .

<AndyS> souri - not quite sure what your asking here - add yourself to queue??

<pfps> When did opaque triple terms even get into the "requirements"?

<TallTed> Need to be explicit about what is meant by "opaque triple term" if we're going to talk about whether they're a requirement.

<AndyS> Hard opaque and soft opaque

<tl> @pfps to provide a not-many-to-many option to AWS

<pchampin> @pfps and https://github.com/w3c/rdf-ucr/wiki/Describing-a-Union-of-Changes-to-a-Named-Graph IMO

<AndyS> Need to be careful about numbers of UCs because we have also said "requirement X is equivalent UC Y" and not gone further.

<niklasl> +1 to not solve philosophical permathreads

<Zakim> TallTed, you wanted to remind that we haven't really built Use Cases & Requirements, so we still cannot evaluate well whether any proposal satisfies more or fewer requirements (and which differ) than any other proposal

<AndyS> Yes to -- "quote what they said" and "talk about what they said"

<tl> +1 to graphs...

<Souri> Just to confirm: Can this be used to represent a path from alice to bob with annotated edges? => :r1 rdf:annotationOf <<' :alice :knows _:b '>> . :r2 rdf:annotationOf <<' _:b :knows :bob '>> . :r1 :linkNum 1 ; :cost 100 . :r2 :linkNum 2 ; :cost 200 .

<pfps> https://github.com/w3c/rdf-ucr/wiki/Summary was generated quite some ago but has not been discussed by the WG.

<AndyS> One triple at a time - isn't this because semantics/entailment in RDF works on triples?

<TallTed> _:b cannot be *understood* to denote the same node in both quoted triples, *however* just as any two blanknode references *could* denote the same node, those *could* denote the same

<tl> @AndyS it's possible to define that an annotation on a graph annotates each triple in the graph (forEach). that IMO solves that issue

<niklasl> But with these opaque, the fact that _:b owl:sameAs _:b .doesn't help, nor anything else?

<AndyS> Yes it can depending on the design. Parser wise it is the same object -- this is "below" denotation. The abstract graph has one bnode term.

<AndyS> ... then there is interpretation.

<AndyS> <<??>> :addToGraph "Tuesday" . <<??>> :factHappened "1850"^^gYear .

<pfps> In opaque contexts, one could arrange things so that the denotation of IRIs, literals, and blank nodes are themselves.

<enrico> pfps: yes, that' would be my "standard name assumption" I mention before.

<niklasl> https://github.com/w3c/rdf-star-wg/wiki/Proposal:-Triple-Tokens-Entailing-Reified-Statements#compatibility-with-existing-use-cases

<pfps> In some sense, this is the natural denotation in opaque contexts. But there is a lot of philosophical discussion on exactly what is the meaning of identifiers in various opqaquey contexts.

<AndyS> Niklasl - I 'm confused by your wiki page that says its a proposal yet you said it's an exploration.

<niklasl> AndyS - It's a proposal, based on Enrico's proposed baseline. But I'm not sure it works (it has issues).

<Souri> Thinking from a user point of view, my feeling is that a type of opacity that allows sharing of terms among opaque triple-terms would be useful, and simpler to understand, in practice. (The opacity of course has to still have many-to-one restriction by not allowing RDF entailment based on an opaque triple-term.)

<AndyS> https://www.w3.org/2002/09/wbs/139681/2024-07-baseline/

Minutes manually created (not a transcript), formatted by scribe.perl version 221 (Fri Jul 21 14:01:30 2023 UTC).

Diagnostics

Succeeded: s|agenda: https://www.w3.org/events/meetings/6d0cd306-0be8-4267-865a-6272cc8d9da4/20230526T100000/||

Succeeded: s/agenda: clear//

Succeeded: s/_c :smurfs :t./_:c :smurfs :t./

Succeeded: s/arrange things so that the denotion/arrange things so that the denotation/

Succeeded: s|pfps - s/the **denotion** of IRIs, literals, and blank nodes are themselves/the **denotation** of IRIs, literals, and blank nodes are themselves/ ?||

Succeeded: s/TallTed - yes//

Active on IRC: AndyS, enrico, gkellogg, niklasl, pchampin, pfps, Souri, TallTed, tl