Dear All,
Obviously, there are two ways in RDF to express what the CRM regards as
an Appellation: Either using a URI, instance of E41, and then another
property specifying in whatever way the symbolic content (I am not
concerned with this here), *OR *using rdfs:label, which has exactly the
meaning of some forms of Appellation that can be expressed exhaustively
as literal.
Interesting enough, there seems to be no existing validation method,
that would exclude any instance of xsd Datatype to be used as range of
rdfs:label.
We have made therefor the following tests with Virtuoso, if P1 can have
two ranges, Literal and E41, and if SPARQL gives the expected answers,
it does:
*1.**Dualism of Appellations*
The purpose of this is to provide an *RDF based technical solution* for
representing and querying a property which can be at the same time Data
and Object type regardless of the fact that it violates the respective
constraints or rules.
Practically we can have three options of representing appellations. By
taking the example of Alexander the Great with supposed URI:
http://example.com/person/alexander_the_great we can do the following:
1)Use the “P1 is identified by” property and an instance of E41
Appellation class:
<http://example.com/person/alexander_the_great>
crm:P1_is_identified_by
<http://example.com/appellation/alexander_the_great> .
<http://example.com/appellation/alexander_the_great>
rdfs:label
"Alexander the Great" .
2)Use directly the rdfs:label:
<http://example.com/person/alexander_the_great>
rdfs:label
"Alexander the Great" .
3)Use the “P1 is identified by” property as a data property (violating
the rdfs definitions):
<http://example.com/person/alexander_the_great>
crm:P1_is_identified_by
"Alexander the Great" .
Based on these examples the following steps were followed to test the
practical application of such cases to a triple store. *Virtuoso triple
store* was used for the following examples.
1.The cidoc_crm.rdfs was altered to include the following:
<rdf:Property rdf:about="P1_is_identified_by">
<rdfs:label xml:lang="en">is identified by</rdfs:label>
<rdfs:domain rdf:resource="E1_CRM_Entity"/>
<rdfs:range rdf:resource="E41_Appellation"/>
</rdf:Property>
<rdf:Property rdf:about="P1_is_identified_by">
<rdfs:label xml:lang="en">is identified by</rdfs:label>
<rdfs:domain rdf:resource="E1_CRM_Entity"/>
<rdfs:range rdf:resource="http://www.w3.org/2000/01/rdf-schema#Literal"/>
</rdf:Property>
**
So,an is identified property was added to the initial schema but with
rdfs:Literal as a range.
2.The cidoc crm schema was uploaded in virtuoso and the following query
(give me the range of P1_is_identified_property) was executed to be sure
that the changes have been applied:
prefix crm: <http://www.cidoc-crm.org/cidoc-crm/>
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>
select * where { crm:P1_is_identified_by rdfs:range ?range}
*result: *
*range*
http://www.cidoc-crm.org/cidoc-crm/E41_Appellation
http://www.w3.org/2000/01/rdf-schema#Literal
So, it is confirmed that the two ranges have been added. I repeat at
this point that Virtuoso *does not apply* any semantic validation. The
purpose of this test is to prove that this exercise is possible even
though conceptually it may not be correct.
3.The ttl data that was presented previously has been added in virtuoso:
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix crm: <http://www.cidoc-crm.org/cidoc-crm/> .
<http://example.com/person/alexander_the_great>
crm:P1_is_identified_by
<http://example.com/appellation/alexander_the_great> .
<http://example.com/appellation/alexander_the_great>
rdfs:label "Alexander the Great" .
<http://example.com/person/alexander_the_great>
rdfs:label "Alexander the Great" .
<http://example.com/person/alexander_the_great>
crm:P1_is_identified_by "Alexander the Great" .
4.A query to return all the “identifiers” of alexander the great using
the is identified property was applied:
prefix crm: <http://www.cidoc-crm.org/cidoc-crm/>
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>
select * where
{ <http://example.com/person/alexander_the_great>crm:P1_is_identified_by
?identifier }
*result: *
*identifier*
http://example.com/appellation/alexander_the_great
Alexander the Great
So, it is obvious that with the same query both the literal and the uri
values are returned.
A version of the above query to return also the appellation’s label (but
not the uri) is the following:
prefix crm: <http://www.cidoc-crm.org/cidoc-crm/>
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>
select ?identifier
where {
{<http://example.com/person/alexander_the_great>crm:P1_is_identified_by
?identifier }
UNION
{<http://example.com/person/alexander_the_great>crm:P1_is_identified_by
?identifier_uri .
?identifier_urirdfs:label ?identifier }
FILTER (!isURI(?identifier))
}
*With the following result :*
*I**dentifier*
Alexander the Great
Alexander the Great
The next question is, if P1 can be declared superproperty of rdfs:label,
so that the query for P1 returns everything CRM regards as Appellation.
It works:
It was tested by altering the cidoc-crm rdfs file, importing it in
virtuoso and asking for the subproperties of rdfs:label as follows:
<rdf:Property rdf:about="P1_is_identified_by">
<rdfs:label xml:lang="en">is identified by</rdfs:label>
<rdfs:label xml:lang="ru">идентифицируется посредством</rdfs:label>
<rdfs:label xml:lang="fr">est identifiée par</rdfs:label>
<rdfs:label xml:lang="pt">é identificado por</rdfs:label>
<rdfs:domain rdf:resource="E1_CRM_Entity"/>
<rdfs:range rdf:resource="E41_Appellation"/>
*<rdfs:subPropertyOf
rdf:resource="http://www.w3.org/2000/01/rdf-schema#label"/>*
</rdf:Property>
Query (Give me all the subproperties of rdfs:label) :
select * where {
?p rdfs:subPropertyOf rdfs:label
}
Result from Virtuoso:
p:
http://www.cidoc-crm.org/cidoc-crm/P1_is_identified_by
I propose this method for the RDFS implementation of the CRM: two ranges
for P1, namely E41 and rdf:Literal, and P1 superproperty of rdfs:label.
Best,
Martin
--
--------------------------------------------------------------
Dr. Martin Doerr | Vox:+30(2810)391625 |
Research Director | Fax:+30(2810)391638 |
| Email: mar...@ics.forth.gr |
|
Center for Cultural Informatics |
Information Systems Laboratory |
Institute of Computer Science |
Foundation for Research and Technology - Hellas (FORTH) |
|
N.Plastira 100, Vassilika Vouton, |
GR70013 Heraklion,Crete,Greece |
|
Web-site: http://www.ics.forth.gr/isl |
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