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Re: RDF* semantics

From: Olaf Hartig <olaf.hartig@liu.se>
Date: Fri, 30 Aug 2019 15:36:26 +0000
To: "public-rdf-star@w3.org" <public-rdf-star@w3.org>
CC: Kingsley Idehen <kidehen@openlinksw.com>
Message-ID: <3241268.QXmiY4GA1b@porty3>
Kingsley,

I notice that the following line in your example document is commented (also 
in the correction that you sent later).

# Alice:  :claims  <http://example.org/Bob> .

Is this line commented intentionally?

Also, in the line you are using the IRI <http://example.org/Bob>, whereas in 
the rest of the document you are using the IRI <http://example.org/Bob#>. 
These are two different IRIs. Was this your intention? If yes, what's the 
reason?

Note that the last five lines part of your document (the part that uses RDF 
reification) can be written more concisely in Turtle* as follows (assuming RDF* 
is used in SA mode):

Alice:  :describes << Bob: foaf:age "23"^^xsd:integer >> .

Thanks,
Olaf


On fredag 30 augusti 2019 kl. 09:57:29 CEST Kingsley Idehen wrote:
> On 8/30/19 8:04 AM, Olaf Hartig wrote:
> > Thomas,
> > 
> > Just to add to Pierre-Antoine's response, perhaps it is necessary to
> > emphasize that you should not get hung up on the fact that the example
> > uses blank nodes. That's also secondary to the point I am trying to
> > make. So, instead of using blank nodes, we may present the example data
> > with two IRIs that denote Alice and Bob, respectively. For instance, if
> > we replace _:b1 by IRI http://example.org/Alice and _:b2 by IRI
> > http://example.org/Bob, then we have the following snippet of Turtle
> > (prefix declarations omitted).
> > 
> > <http://example.org/Alice>  rdf:type  foaf:Person .
> > <http://example.org/Alice>  foaf:name  "Alice" .
> > <http://example.org/Alice>  :claims  <http://example.org/Bob> .
> > <http://example.org/Bob>  rdf:type  foaf:Person .
> > <http://example.org/Bob>  foaf:name  "Bob" .
> > <http://example.org/Bob>  foaf:age "23"^^xsd:integer .
> > 
> > Perhaps now it becomes more apparent that, according to this data,
> > person Alice claims the person Bob (who is of age 23). This is different
> > than saying that person Alice makes the following claim: the thing
> > denoted by IRI is a person named Bob who is of age 23.
> > 
> > Best,
> > Olaf
> 
> Hi Olaf,
> 
> I think your example above needs a little more context i.e., clarity of
> the relationship type (i.e., :claims in this example) that connects
> Alice and Bob. Here's how I would add the missing context using
> RDF-Turtle notation.
> 
> 
> Fundamentally, the claims (in the form of a collection of RDF
> statements) made by Alice are conveyed in a Document.
> 
> ## Turtle Start ##
> 
> @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
> @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
> @prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
> @prefix foaf: <http://xmlns.com/foaf/0.1/> .
> @prefix Alice: <http://example.org/Alice#>.
> @prefix Bob: <http://example.org/Bob#> .
> @prefix : <#> .
> 
> <> a foaf:Document .
> <> foaf:name "Document about Alice"@en .
> <> foaf:primaryTopic Alice: .
> 
> 
> Alice:  rdf:type  foaf:Person .
> Alice:  foaf:name  "Alice" .
> 
> # Alice:  :claims  <http://example.org/Bob> .
> 
> Bob:  rdf:type  foaf:Person .
> Bob:  foaf:name  "Bob" .
> Bob:  foaf:age "23"^^xsd:integer .
> 
> # Context clarity regarding :describes relation
> 
> :describes a rdf:Property .
> :describes rdfs:domain foaf:Person .
> :describes rdfs:range rdf:Statement .
> 
> Alice:  :describes  [ a rdf:Statement;
>                         rdf:subject Bob: ;
>                         rdf:predicate foaf:age ;
>                         rdf:object "23"^^xsd:integer
>                     ] .
> 
> ## Turtle End ##
> 
> Links:
> 
> [1]
> https://kingsley.idehen.net/public_home/kidehen/Public/Linked%20Data%20Docu

> ments/Tutorials/label-property-graph-stuff/alice-describes-bob.txt -- Text
> document that nanotation-friendly (i.e., processed by our OSDS Browser
> Extension for visualization effect)
> 
> [2]
> https://kingsley.idehen.net/public_home/kidehen/Public/Linked%20Data%20Docu

> ments/Tutorials/label-property-graph-stuff/alice-describes-bob.ttl --
> RDF-Turtle Document


Received on Friday, 30 August 2019 15:36:54 UTC

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