Re: The way forward

This appears to again be a fundamental misreading of what RDF is about.

The RDF graph
:Liz :spouse :Dick .
:Liz :spouse :Eddie .
does not say that the spouse of Liz is the collection (or set) of :Dick and 
:Eddie.  It instead says that a spouse of Liz is Dick and a spouse of Liz is 
Eddie.

Similarly, the RDF graph
:r rdf:reifies << :a :b :c >> .
:r rdf:reifies << :d :e :f >> .
does not say that :r reifies a collection (or set) of two quoted triples.  It 
instead that there are two quoted triples that :r reifies.
And so
<< :r | :a :b :c >> :x :y .
<< :r | :d :e :f >> :x :y .
should  not say that :r reifies a collection (or set) of two quoted triples or 
even an RDF graph.  Instead there are two quoted triples that :r reifies, and 
nothing else should be read into it.

peter


On 4/29/24 13:00, Thompson, Bryan wrote:
> Niklas,
> 
> 
> I am drawing a distinction between making statements about a specific 
> statement and making statements about a collection of statements.  I think it 
> is a mistake to consider the latter simple a more general version of the 
> former.  The ability to have metadata about a specific statement is the key 
> enabler (Statements about Statements) for edge properties (for RDF, leaving 
> LPG out of this), statement level provenance for RDF, etc.
> 
> 
> The ability to make statements about statement sets is different.  It does not 
> support this basic mechanism of describing a specific statement unless a 
> constraint is imposed such that the "Graph" is a single statement.
> 
> 
> I think that talking about this as Statements about Statements (SAS) vs 
> Statements about Graphs (SAG) highlights the difference.
> 
> 
> The risk here is that people see SAG as more general, but in fact it is unable 
> to support SAS without some constraint (e.g., a well-formedness constraint, a 
> profile, etc.).
> 
> 
> It was these SAS use cases that motivated RDR, RDF*, and the creating of this 
> working group.
> 
> 
> I am happy to see the WG support both, but let's not forget the motivating use 
> cases of SAS.
> 
> 
> Bryan
> 
> ------------------------------------------------------------------------------
> *From:* Niklas Lindström <lindstream@gmail.com>
> *Sent:* Friday, April 26, 2024 12:26:45 AM
> *To:* Thompson, Bryan
> *Cc:* Peter F. Patel-Schneider; 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.
> 
> 
> 
> 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 
> <https://www.w3.org/TR/rdf12-concepts/#resources-and-statements>>
> [2]: <https://www.w3.org/TR/rdf12-concepts/#entailment 
> <https://www.w3.org/TR/rdf12-concepts/#entailment>>
> [3]: <https://www.w3.org/TR/rdf12-concepts/#section-rdf-graph 
> <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
>>

Received on Thursday, 2 May 2024 13:50:13 UTC