Re: The way forward

None of this changes the fundamental reading of multiplicity in RDF.  Nothing 
in SPARQL implies that multiplicity in RDF is to be treated in a collective or 
set-based fashion, just as the Python built-in ability to construct a list or 
dictionary from arguments to a function call does not imply that the arguments 
are a list or dictionary.

peter


On 5/2/24 18:47, Thompson, Bryan wrote:
> Any query language will read a lot more into it.  Run "SELECT ?spouse WHERE { 
> :Liz :spouse ?spouse }".  You get back a solution multi-set of bindings for 
> ?spouse.  Add GROUP BY with CONCAT and you can get an xsd:string of those 
> values combined.   If you use FOLD (from work on composite data types), you 
> will get back a list.
> 
> 
> You might be saying that the RDF MT does not say anything more about it, but 
> databases do quite a bit with RDF data that they match in queries.  The 
> "interpretation" is then specified by the SPARQL specification.
> 
> 
> Bryan
> 
> ------------------------------------------------------------------------------
> *From:* Peter F. Patel-Schneider <pfpschneider@gmail.com>
> *Sent:* Thursday, May 2, 2024 6:50:08 AM
> *To:* Thompson, Bryan; Niklas Lindström
> *Cc:* 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 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 
> <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 
> <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 
> <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 23:11:54 UTC