Re: Well-formedness for option 3

Dear Enrico,

Thanks for your responses and the examples!

Is it correct to say that all of these example rely on referential
transparency of triple terms or is the intention behind these examples
not related to referential transparency?

And another question: Is it correct to say that my Property 2 and the
idea of referential transparency of triple terms exclude one another?

Thanks,
Olaf


On Wed, 2024-02-28 at 10:12 +0000, Franconi Enrico wrote:
> Really I meant:
> << :b1 | :enrico :born-in :rome >> :on-date 1962 .
> << :b1 | :enrico :born-on 1962 >> :location :rome .
>
> On 28 Feb 2024, at 11:00, Franconi Enrico <franconi@inf.unibz.it>
> wrote:
>
> Even better:
> << :b1 | :enrico :born-in :rome >> :on-date 1962 .
> << :b1 | :enrico :born-on 1964 >> :location :rome .
>
> —e.
>
> > On 28 Feb 2024, at 10:31, Franconi Enrico <franconi@inf.unibz.it>
> > wrote:
> >
> > A better example, to avoid the temptation to believe that you may
> > need owl:same-as:
> > << :w3 | :bill-clinton :related-to :hillary-rodham >> :starts 1975
> > .
> > << :w3 | :1st-female-NY-senator :wife :42nd-potus >> :starts 1975 .
> > Note that :related-to and :wife denote distinct properties.
> > —e.
> >
> > > On 28 Feb 2024, at 10:27, Franconi Enrico <franconi@inf.unibz.it>
> > > wrote:
> > >
> > > Indeed your property 2 is highly controversial and I have
> > > rejected it with all may energy in several past messages.
> > > An example:
> > > << :w3 | :bill-clinton :related-to :hillary-rodham >> :starts
> > > 1975 .
> > > << :w3 | :42nd-potus :husband :1st-female-NY-senator >> :starts
> > > 1975 .
> > > cheers
> > > —e.
> > >
> > > > On 28 Feb 2024, at 10:23, Olaf Hartig <olaf.hartig@liu.se>
> > > > wrote:
> > > >
> > > > Thanks for the pointer Enrico! I was assuming that this
> > > > document
> > > > defines only the semantics but I see now that you define a
> > > > notion
> > > > of reification well-formed graphs at the end of this document.
> > > >
> > > > I notice that this notion covers Property 1 of my definition
> > > > (in the
> > > > email below), but not Property 2.
> > > >
> > > > -Olaf
> > > >
> > > >
> > > > On Wed, 2024-02-28 at 09:09 +0000, Franconi Enrico wrote:
> > > > > As mentioned several times, you can find the current proposed
> > > > > formalisation of option 3 here:
> > > > > https://github.com/w3c/rdf-star-wg/wiki/RDF%E2%80%90star-semantics%3A-option-3

> > > > > cheers
> > > > > —e.
> > > > >
> > > > > > On 28 Feb 2024, at 10:03, Olaf Hartig <olaf.hartig@liu.se>
> > > > > > wrote:
> > > > > >
> > > > > > Dear all,
> > > > > >
> > > > > > Do we have an email or a document with a definition of
> > > > > > well-
> > > > > > formedness
> > > > > > in the context of option 3? I couldn't find any, but
> > > > > > perhaps I
> > > > > > overlooked something.
> > > > > >
> > > > > > The words “well-formed” and “well-formedness” were
> > > > > > mentioned in
> > > > > > recent
> > > > > > calls that took place after the call in which we came to
> > > > > > the
> > > > > > consensus
> > > > > > to focus on option 3. So, I assume that group members have
> > > > > > an
> > > > > > understanding what the notion of well-formedness for option
> > > > > > 3
> > > > > > means.
> > > > > > Yet, I couldn’t find any form of definition for it. The
> > > > > > only
> > > > > > definition
> > > > > > that I found is the one of a “reification well-formed RDF
> > > > > > graph” by
> > > > > > Peter [1], but that one is focused on options 1 and 2, and
> > > > > > not
> > > > > > directly
> > > > > > applicable to option 3.
> > > > > >
> > > > > > So, what is your understanding of a well-formed RDF graph
> > > > > > in the
> > > > > > context of option 3?
> > > > > >
> > > > > > Mine is as follows: An RDF graph is well formed iff it has
> > > > > > all of
> > > > > > the
> > > > > > following properties.
> > > > > >
> > > > > > - Property 0: None of the triples in the graph has a triple
> > > > > > term
> > > > > > [2] as
> > > > > > its subject.
> > > > > > (In my reading of option 3, triple terms in the subject are
> > > > > > already
> > > > > > ruled out by the abstract syntax itself, which makes
> > > > > > mentioning
> > > > > > this
> > > > > > property here obsolete. Yet, I still mention it for the
> > > > > > moment
> > > > > > because
> > > > > > some group members seem to argue for an abstract syntax in
> > > > > > which
> > > > > > triple
> > > > > > terms may be used in the subject position.)
> > > > > >
> > > > > > - Property 1: For every triple in the graph that has a
> > > > > > triple term
> > > > > > as
> > > > > > its object, the predicate of this triple must be
> > > > > > rdf:nameOf.
> > > > > > (I understand that the name of this predicate IRI is still
> > > > > > under
> > > > > > discussion.)
> > > > > >
> > > > > > - Property 2: For every pair of triples in the graph, if
> > > > > > both
> > > > > > triples
> > > > > > have a triple term as their object (and, thus, have
> > > > > > rdf:nameOf as
> > > > > > their
> > > > > > predicate, as per the previous point above) and these two
> > > > > > triple
> > > > > > terms
> > > > > > are different from one another, then the two triples must
> > > > > > not have
> > > > > > the
> > > > > > same subject.
> > > > > >
> > > > > > I assume that Property 2 might be controversial. It has the
> > > > > > disadvantage that merging two well-formed graphs may result
> > > > > > in a
> > > > > > graph
> > > > > > that is not well formed according to the notion of well-
> > > > > > formedness
> > > > > > with
> > > > > > Property 2 included. However, well-formedness without
> > > > > > Property 2
> > > > > > makes
> > > > > > implementations that focus on efficient support for well-
> > > > > > formed
> > > > > > graphs
> > > > > > significantly harder; I mean, without Property 2, such
> > > > > > implementations
> > > > > > cannot employ data structures (e.g., indexes) that assume
> > > > > > that the
> > > > > > subjects of rdf:nameOf triples functionally determine the
> > > > > > triple
> > > > > > terms.
> > > > > > Notice also that Property 2 is essentially the option-3
> > > > > > variant of
> > > > > > Peter’s aforementioned notion of a “reification well-formed
> > > > > > RDF
> > > > > > graph”
> > > > > > for options 1 and 2.
> > > > > >
> > > > > > An idea to eliminate the aforementioned disadvantage of
> > > > > > including
> > > > > > Property 2 is to allow only blank nodes in the subject of
> > > > > > rdf:nameOf
> > > > > > triples, but that’s probably not very desirable either
> > > > > > because it
> > > > > > would
> > > > > > mean that “occurrences” cannot be named by an IRI. Still, I
> > > > > > thought
> > > > > > I
> > > > > > should mention this idea as a possible option to address
> > > > > > the
> > > > > > undesirable effect on graph merging that Property 2 would
> > > > > > imply.
> > > > > >
> > > > > > Best,
> > > > > > Olaf
> > > > > >
> > > > > > [1]
> > > > > > https://github.com/w3c/rdf-star-wg/blob/main/docs/sugar-proposal.md#criticisms-and-responses

> > > > > >
> > > > > > [2]
> > > > > > https://pr-preview.s3.amazonaws.com/w3c/rdf-concepts/pull/78.html#dfn-triple-term

> > > > > >
> > > > >
> > > > >
> > >
> >
>
>

Received on Wednesday, 28 February 2024 13:47:43 UTC