Re: The way forward

Hm...

In my intuition not every set of statements is a graph. An RDF standard reification quad is a set of 4 statements, but is it a graph? Rather not, at least not without a further act of 'demarcation', e.g. by putting it in its own RDF 1.1 named graph or Turtle file etc

An RDF 1.2 reifier reifies one or more triple terms.
Is a triple term a statement? Rather not, since it is not asserted.
Therefore the reifier only refers to the description of such a (set of) statements(s), where said description is given by triple term(s).

The connection between such a reification and actually asserted statements in a graph that fit that description is brittle, and might be purely coincidental. E.g. one might describe/reify and annotate such statements without any intent of actually asserting them, and yet the same graph might contain those very statements and there's no way to tell without explicit annotations on the reification (e.g. saying that the reification is supposed to be asserted, maybe driving respective materialization). 

Thomas


P.s.: the fact that the reifier construct doesn't refer to any particular asserted statement IMO constitutes a much wider gap between RDF and LPG than the x-to-many issue. 




Am 26. April 2024 09:26:45 MESZ schrieb "Niklas Lindström" <lindstream@gmail.com>:
>Bryan,
>
>1.How come, given this:
>
>    <e1> rdf:reifies <<( <s1> :p1 <o1> )>> .
>    <e1> rdf:reifies <<( <s2> :p2 <o2> )>> .
>
>you say that we're making statements about a graph, whereas with:
>
>    <e1> rdf:reifies <<( <s1> :p1 <o1> )>> .
>
>we are not? With your notion. how would you make statements about a
>graph of only one triple?
>
>Also, would you say that here:
>
>    <john> foaf:knows <jane> .
>    <john> foaf:knows <mary> .
>
>we are making statements about the set of <jane> and <mary>? Does
><john> know that set? Does the set contain two persons, or two IRIs?
>
>I suspect that in the sentence "making statements about a graph" there
>is an unwitting change of context, from the domain of discourse to its
>representation (which are not necessarily different, but quite often).
>
>2. I'm not entirely sure what you mean by "making statements about
>statements". From [1]: "Asserting an RDF triple says that some
>relationship, indicated by the predicate, holds between the resources
>denoted by the subject and object. This statement corresponding to an
>RDF triple is known as an RDF statement." But then you talk about
>triples, and graphs, i.e. sets of triples. Do you consistently refer
>to the triple (the encoding) or the statement denoted by the triple
>(the expression)? I would say we're making statements about
>statements, by asserting triples where the object is another triple.
>Many-to-one or many-to-many does not change that.
>
>See also [2]: "An RDF triple encodes a statement—a simple logical
>expression, or claim about the world. An RDF graph is the conjunction
>(logical AND) of its triples."
>
>Aside: Considering [3]: "An RDF graph is a set of RDF triples", I
>don't think this working group is in agreement on whether a graph is
>EXACTLY a set of triples (i.e. by definition, these two names denote
>the same mathematical concept), or if a graph is a set of triples, but
>not all sets of triples are graphs. (And here I do not mean "named
>graphs" at all, which is a pair of a name (IRI or bnode) and this
>graph notion. Of course, I do not know if that's supposed to mean all
>such pairs; but that's hopefully beside the point...)
>
>We may want to address these matters in today's semantics meeting.
>
>Best regards,
>Niklas
>
>[1]: <https://www.w3.org/TR/rdf12-concepts/#resources-and-statements>
>[2]: <https://www.w3.org/TR/rdf12-concepts/#entailment>
>[3]: <https://www.w3.org/TR/rdf12-concepts/#section-rdf-graph>
>
>
>
>On Fri, Apr 26, 2024 at 1:07 AM Thompson, Bryan <bryant@amazon.com> wrote:
>>
>> I do not believe that you answered my question Peter.   What do you want to call that set of Subject Predicate Object tuples?  At any rate, I will call it a graph and your proposal is making statements about those sets.  E.g., Statements about Graphs.
>>
>>
>> Bryan
>>
>> ________________________________
>> From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
>> Sent: Thursday, April 25, 2024 4:04:46 PM
>> To: public-rdf-star-wg@w3.org
>> Subject: RE: [EXTERNAL] The way forward
>>
>> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe.
>>
>>
>>
>> This is a fundamental misconception.  Consider complex numbers.  They are an
>> ordered pair of real numbers, but there is no way that every ordered pair of
>> real numbers has to be considered a complex number.  Similarly a set of RDF
>> triples, let alone several RDF triples not collected into a set, is not
>> necessarily an RDF graph.
>>
>> peter
>>
>>
>> On 4/25/24 13:48, Thompson, Bryan wrote:
>> > What do you call a set of S, P, O tuples?  I call it a Graph.  Your proposal is to reify such sets.  Hence, Statements about Graphs.
>> >
>> > Bryan
>>
>