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
[log in to unmask] http://kcoyle.net
m: 1-510-435-8234
skype: kcoylenet