Re: Well-formedness for option 3

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‐star-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 10:12:33 UTC