On 11/3/13 12:45 PM, Eric Lease Morgan wrote:
Cool input. Thank you. I believe I have tweaked my assertions:
1. The Declaration of Independence was written by Thomas Jefferson
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";
xmlns:dc="http://purl.org/dc/elements/1.1/"; >
<rdf:Description
rdf:about="http://www.archives.gov/exhibits/charters/declaration_transcript.html";>
<dc:creator>http://id.loc.gov/authorities/names/n79089957</dc:creator>
</rdf:Description>
</rdf:RDF>
To refer to the DoI itself rather than a web page you can use either a
wikipedia or dbpedia URI:
http://en.wikipedia.org/wiki/Declaration_of_Independence
Also, as has been mentioned, it would be best to use dcterms rather than
dc elements, since the assumption with dcterms is that the value is an
identifier rather than a string. So you need:
http://purl.org/dc/terms/
which is either expressed as "dct" or "dcterms"
The dc/1.1/ has in a sense been "upgraded" by dc/terms/ but I recently
did a study of actual usage of Dublin Core in linked data and in fact
both are heavily used, although dcterms is by far the most common usage
due to its compatibility with RDF.
http://kcoyle.blogspot.com/2013/10/dublin-core-usage-in-lod.html
http://kcoyle.blogspot.com/2013/10/who-uses-dublin-core-dcterms.html
http://kcoyle.blogspot.com/2013/10/who-uses-dublin-core-original-15.html
2. Thomas Jefferson is a male person
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";
xmlns:foaf="http://xmlns.com/foaf/0.1/";>
<rdf:Description rdf:about="http://id.loc.gov/authorities/names/n7908995";>
<foaf:Person foaf:gender="male" />
</rdf:Description>
</rdf:RDF>
Using no additional vocabularies (ontologies), I think my hypothetical Linked
Data spider / robot ought to be able to assert the following:
3. The Declaration of Independence was written by Thomas Jefferson, a male
person
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";
xmlns:dc="http://purl.org/dc/elements/1.1/";
xmlns:foaf="http://xmlns.com/foaf/0.1/";>
<rdf:Description
rdf:about="http://www.archives.gov/exhibits/charters/declaration_transcript.html";>
<dc:creator>
<foaf:Person rdf:about="http://id.loc.gov/authorities/names/n79089957";>
<foaf:gender>male</foaf:gender>
</foaf:Person>
</dc:creator>
</rdf:Description>
</rdf:RDF>
The W3C Validator…validates Assertion #3, and returns the attached graph, which
illustrates the logical combination of Assertion #1 and #2.
This is hard. The Semantic Web (and RDF) attempt at codifying knowledge using a
strict syntax, specifically a strict syntax of triples. It is very difficult
for humans to articulate knowledge, let alone codifying it. How realistic is
the idea of the Semantic Web? I wonder this not because I don’t think the
technology can handle the problem. I say this because I think people can’t (or
have great difficulty) succinctly articulating knowledge. Or maybe knowledge
does not fit into triples?
I agree that it is hard, although it gets easier as you lose some of
your current data processing baggage and begin to think more in terms of
triples. For that, like Ross, I really advise you not to do your work in
RDF/XML -- in a sense RDF/XML is a kluge to force RDF into XML, and it
is much more complex than RDF in turtle or plain triples.
I also agree that not all knowledge may fit nicely into triples. RDF is
great for articulations of things and relationships. Your example here
is a perfect one for RDF. In fact, it is very simple conceptually and
could be quite simple as triples. Conceptually you are saying:
URI:DoI -> dct:creator -> URI:TJeff
URI:Tjeff -> RDF:type -> foaf:Person
URI:Tjeff -> foaf:gender -> "male"
<!-- I bet we can find a URI for male/female/? -->
I've experimented a bit with using iPython (with Notebook) and the
python rdflib, which can create a virtual triple-store that you can
query against:
http://www.rdflib.net/
Again, it's all soooooo much easier if you don't use rdfxml.
kc
—
Eric Morgan
University of Notre Dame
[cid:6A4E613F-CE41-4D35-BDFA-2E66EE7AF20A]
--
Karen Coyle
kco...@kcoyle.net http://kcoyle.net
m: 1-510-435-8234
skype: kcoylenet
