- From: Franconi Enrico <franconi@inf.unibz.it>
- Date: Wed, 28 Feb 2024 17:56:06 +0000
- To: Olaf Hartig <olaf.hartig@liu.se>
- CC: "public-rdf-star-wg@w3.org" <public-rdf-star-wg@w3.org>
> On 28 Feb 2024, at 14:47, Olaf Hartig <olaf.hartig@liu.se> wrote: > 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? It is not related. Those examples are about the fact that distinct predications (independently on the transparency/opacity of their arguments) may induce the same event/situation. I guess that this may happen also in the case non-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? Please give me an example of your intuition, i can't understand why you are saying this. cheers —e. > > 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 17:56:13 UTC