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Re: RDF* semantics

From: Kingsley Idehen <kidehen@openlinksw.com>
Date: Wed, 7 Aug 2019 10:37:36 -0400
To: public-rdf-star@w3.org
Message-ID: <fa10d307-fb6d-3aa2-60d5-0c6a089659c1@openlinksw.com>
On 8/7/19 5:13 AM, Olaf Hartig wrote:
> Hi Kingsley,
> On Tue, 2019-08-06 at 12:16 -0400, Kingsley Idehen wrote:
>> On 8/6/19 11:12 AM, Olaf Hartig wrote:
>>> Hi Kingsley,
>>> On Mon, 2019-08-05 at 13:52 -0400, Kingsley Idehen wrote:
>>>> [...]
>>>> Under what circumstances in the real-world would the condition you model
>>>> arise i.e., propositions that don't manifest as part of documentation?
>>> For instance, we my want to capture that Alice told us that Bob's age is
>>> 23, even if we don't have a document from Alice with this
>>> statement/claim regarding Bob's age.
>> Through what medium did Alice make the aforementioned claim about Bob?
> As I wrote, she *told* us (during a conversation in a cafe, if you
> like).

But that's just another RDF sentence/statement constructed from blank
nodes (indefinite pronouns):

@prefix : <#> .

[ a foaf:Person; foaf:name "Alice"] :claims [a foaf:Person; foaf:name
"Bob"; foaf:age "23"^^xsd:integer] .

Thus, it still retains the fundamental subject, predicate, object
structure covered by terms in the RDF Vocabulary
<http://www.w3.org/1999/02/22-rdf-syntax-ns#> for describing the
components of an rdf:Statement.

I am delivering this communication via a document dispatched via email
(courtesy of smtp protocol). You may or may not agree with my
communication, but you can referred to said communication based on its
delivery medium.

I didn't just say something, I said it in an email document that has its
own provenance data (or metadata) etc..

>> How is provenance articulated in said medium?
> Similar to how you may have included provenance information in your
> example document, Alice's spoken sentences may have included hints about
> the provenance of her claim regarding Bob's age.
> However, I don't see why this is relevant in our context in which we aim
> to capture provenance of the claim regarding Bob's age in *another*
> medium, where the provenance of the claim is that we have heard it from
> Alice and the other medium is an RDF* graph (or a Turtle* serialization
> thereof, if you like).
>>  [...]
>>>> The triple:
>>>> @prefix : <#> .
>>>> :bob foaf:age "23"^^xsd:integer . 
>>>> Exists in a document identified by <> , so we a missing the following part
>>>> of reality (as I understand it):
>>>> @prefix : <#> . 
>>>> <> a foaf:Document .
>>>> <> :creator :i .
>>>> <> :createdOn "2019-08-05"^^xsd:date . 
>>>> <> foaf:primaryTopic :bob. 
>>>> :bob foaf:age "23"^^xsd:integer . 
>>>> Thus, it's the authoritative weight given to <>, by whoever, under whatever
>>>> situation and circumstance, that leads to acceptance or rejection of the
>>>> claims outlined e.g., those about the foaf:age of the entity identified
>>>> by :bob .
>>> I am not questioning that. Note, however, that your document is not
>>> making a statement/claim about the claim regarding Bob's age (other than
>>> asserting it, of course).
>> The document is the medium through which those claims are projected. Put
>> differently, it provides the surface for the claim represented as
>> sentences/statements.
> I have no problem with that. But again, while your example document
> contains the statement about Bob's age and some statement about itself
> (including provenance-related statements), it does not contain any
> statement about the statement about Bob's age.

It could, but it would simply be more verbose, which is what appears to
be the issue with reification as it currently exists. Not the semantics
of RDF per se.

>>> The purpose of RDF*, and of RDF reification,
>>> is to allow you to do so (within your document or within another of your
>>> documents).
>> I understand the RDF reification part since it allows one speak directly
>> about units of communication or "parts of speach" (subject, predicate,
>> and object components of RDF sentences/statements) using documentation,
>> just like anything else.
>> At this juncture, I see RDF* as being about an algorithm (delivered as
>> syntax sugar) for attempting to address the verbosity of  existing RDF
>> reification syntax rather than dealing with new RDF semantics.
> Fine with me. Under the perspective that considers RDF* purely as
> syntactic sugar, we have the existing RDF semantics and don't need
> anything new (except for a mapping that defines how the syntactic
> extension maps to standard RDF, but that we have).
> However, as an alternative to the syntactic-sugar perspective, another
> perspective is to consider RDF* to be based on its own abstract data
> model (which is an extension of the RDF data model).

An alternative abstract data model is certainly a cleaner approach, but
that isn't really RDF anymore. Thus, RDF* would lead to confusion, IMHO.

>  Then, as has been
> done for the RDF data model, we may define a semantics related to the
> RDF* data model. Pat's initial point was that such a semantics will help
> to provide some clarity (under this alternative perspective, I assume).

I'll let Pat speak for himself :)


> Olaf
>> Anyway, that's why "RDF* semantics" is confusing to me with regards to
>> its fundamental objective at this point in time.
>> Kingsley
>>> Best,
>>> Olaf
>>>> If we get the world we a modeling for clear, other bits of the problem
>>>> will become clearer.
>>>> Conclusion:
>>>> In my opinion, we need a complete example that's relatable to the world
>>>> that we are describing using RDF sentences :)


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Received on Wednesday, 7 August 2019 14:38:03 UTC

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