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Re: RDF* semantics

From: Kingsley Idehen <kidehen@openlinksw.com>
Date: Sat, 17 Aug 2019 14:44:40 -0400
To: public-rdf-star@w3.org
Message-ID: <de0daa78-6220-2c55-b23a-72445be4a908@openlinksw.com>
On 8/17/19 12:19 PM, Martynas Jusevičius wrote:
> Kingsley,
>
> don't you mean
>
> [ a foaf:Person; foaf:name "Alice"] :claims { [a foaf:Person;
> foaf:name "Bob"; foaf:age "23"^^xsd:integer] . } .
>
> Note the graph designation.


Not as presented syntactically as that isn't RDF-Turtle notation.

Here's are document URL that includes content representing what Olaf and
I are discussing, using RDF-Turtle notation or Nanotation (i.e,
"text/plain" file that's readable as is or via our OSDS Browser
Extension
<https://chrome.google.com/webstore/detail/openlink-structured-data/egdaiaihbdoiibopledjahjaihbmjhdj?hl=en#this>for
visualization):

My original statements in documents without reification :

1. 
https://kingsley.idehen.net/public_home/kidehen/Public/Linked%20Data%20Documents/Tutorials/label-property-graph-stuff/alice-claims-about-bob.txt
-- RDF-Turtle Nanotation in plain text (i.e., "text/plain" content-type)

2.
https://kingsley.idehen.net/public_home/kidehen/Public/Linked%20Data%20Documents/Tutorials/label-property-graph-stuff/alice-claims-about-bob.ttl
-- RDF-Turtle (i.e., "text/turtle" content-type)


Documents comprising reified statements (as per what Olaf is speaking
about primarily) using terms from the RDF Vocabulary
<http://www.w3.org/1999/02/22-rdf-syntax-ns#>:

1.
https://kingsley.idehen.net/public_home/kidehen/Public/Linked%20Data%20Documents/Tutorials/label-property-graph-stuff/alice-claims-about-bob-reified.txt
-- RDF-Turtle Nanotation in plain text (i.e., "text/plain" content-type)

2.
https://kingsley.idehen.net/public_home/kidehen/Public/Linked%20Data%20Documents/Tutorials/label-property-graph-stuff/alice-claims-about-bob-reified.ttl
-- RDF-Turtle Nanotation in plain text (i.e., "text/plain" content-type)


As I see it, the issue we are debating is primarily about reification
and syntax sugar for articulation convenience i.e., does this actually
constitute what's denoted as RDF* Semantics (for which I am currently
unconvinced, bearing in mind what exists regarding the roles of RDF
[DDL] and SPARQL [DML] which offers Named Graphs as a solution).


Kingsley


>
> On Wed, Aug 14, 2019 at 5:02 PM Kingsley Idehen <kidehen@openlinksw.com> wrote:
>> On 8/8/19 6:13 AM, Olaf Hartig wrote:
>>> On Wed, 2019-08-07 at 12:04 -0400, Kingsley Idehen wrote:
>>>> [...]
>>>>>> 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] .
>>>>>>
>>>> [...]
>>>>
>>>> It states that a Person named "Alice" :claims a Person named "Bob" has
>>>> age 23 expressed as in integer.
>>> I disagree. It states that a Person named "Alice" :claims something and
>>> this something is of rdf:type foaf:Person. So, what she is claiming is a
>>> person rather than being about a person.
>>
>> I hope you are not interpreting :clams somewhat whimsically, since I
>> didn't actually assert that the rdfs:range of :claims is an
>> rdf:Statement instance in my original example sentence. I could have
>> written my example as follows, to be more precise:
>>
>> @prefix : <#> .
>>
>> :claims a rdf:Property ;
>>         rdfs:range owl:Thing .
>>
>> [ a foaf:Person; foaf:name "Alice"] :claims [a foaf:Person; foaf:name
>> "Bob"; foaf:age "23"^^xsd:integer] .
>>
>>
>> If on the other hand I had stated:
>>
>> @prefix : <#> .
>>
>> :claims a rdf:Property ;
>>         rdfs:range owl:Thing .
>>
>> [ a foaf:Person; foaf:name "Alice"] :claims [a foaf:Person; foaf:name
>> "Bob"; foaf:age "23"^^xsd:integer] .
>>
>>
>> Then I would be articulating what you assumed, and my sentence would then be incorrect :)
>>
>> BTW -- I can also do all of this in a document (as per SPARQL Named
>> Graphs) and just pepper the document with additional metadata for
>> provenance purposes. Basically, why aren't  SPARQL Named Graphs a viable
>> solution to this problem i.e., RDF stays as is for data definition while
>> languages such as SPARQL handle operations on RDF structured data?
>>
>>
>>>> [...]
>>>>> I guess what you actually wanted to write was something
>>>>> like the following:
>>>>>
>>>>> [ a foaf:Person; foaf:name "Alice"]
>>>>>            :claims [ a rdf:Statement ;
>>>>>                      rdf:subject   :Bob ;
>>>>>                      rdf:predicate foaf:age ;
>>>>>                      rdf:object    "23"^^xsd:integer ] .
>>>> No, that is just a reified version of my initial statement.
>>> Are you saying that you consider the set of triples serialized as this
>>> piece of Turtle to be semantically equivalent to the set of triples
>>> serialized in the piece of Turtle above?
>>
>> Of course not.
>>
>>
>> Kingsley
>>
>>>> [...]
>>>>> By the definition of the RDF* data model, every RDF graph is an RDF*
>>>>> graph. Additionally, by the definition of the RDF*-to-RDF mapping, every
>>>>> RDF* graph can be viewed as an RDF graph.
>>>> Sorta, but this is serious work to be done explaining all of this in a
>>>> manner that prevents the confusion I fear.
>>> Point taken.
>>>
>>> Olaf
>>>
>>>
>>>
>> --
>> Regards,
>>
>> Kingsley Idehen
>> Founder & CEO
>> OpenLink Software
>> Home Page: http://www.openlinksw.com
>> Community Support: https://community.openlinksw.com
>> Weblogs (Blogs):
>> Company Blog: https://medium.com/openlink-software-blog
>> Virtuoso Blog: https://medium.com/virtuoso-blog
>> Data Access Drivers Blog: https://medium.com/openlink-odbc-jdbc-ado-net-data-access-drivers
>>
>> Personal Weblogs (Blogs):
>> Medium Blog: https://medium.com/@kidehen
>> Legacy Blogs: http://www.openlinksw.com/blog/~kidehen/
>>               http://kidehen.blogspot.com
>>
>> Profile Pages:
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>>
>> Web Identities (WebID):
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>>         : http://id.myopenlink.net/DAV/home/KingsleyUyiIdehen/Public/kingsley.ttl#this
>>
>>
>

-- 
Regards,

Kingsley Idehen	      
Founder & CEO 
OpenLink Software   
Home Page: http://www.openlinksw.com
Community Support: https://community.openlinksw.com
Weblogs (Blogs):
Company Blog: https://medium.com/openlink-software-blog
Virtuoso Blog: https://medium.com/virtuoso-blog
Data Access Drivers Blog: https://medium.com/openlink-odbc-jdbc-ado-net-data-access-drivers

Personal Weblogs (Blogs):
Medium Blog: https://medium.com/@kidehen
Legacy Blogs: http://www.openlinksw.com/blog/~kidehen/
              http://kidehen.blogspot.com

Profile Pages:
Pinterest: https://www.pinterest.com/kidehen/
Quora: https://www.quora.com/profile/Kingsley-Uyi-Idehen
Twitter: https://twitter.com/kidehen
Google+: https://plus.google.com/+KingsleyIdehen/about
LinkedIn: http://www.linkedin.com/in/kidehen

Web Identities (WebID):
Personal: http://kingsley.idehen.net/public_home/kidehen/profile.ttl#i
        : http://id.myopenlink.net/DAV/home/KingsleyUyiIdehen/Public/kingsley.ttl#this




Received on Saturday, 17 August 2019 18:45:08 UTC

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