[Om] Content Dictionary for Linked Data with RDF

Christoph LANGE ch.lange at jacobs-university.de
Thu Mar 1 14:13:16 CET 2012

Hi Ken,

some more comments on the RDF CD now that I looked into it:

I don't feel comfortable with the approach for representing RDF resource 
URIs as strings.

I agree that it may be useful to apply the rdf.resourceset operator to 
more complex descriptions of RDF resources, and now that I see how it 
works, I agree that OWL Manchester syntax is a reasonable approach, that 
my initial Turtle suggestion is nonsense – but then maybe SPARQL might 
be more appropriate, as it is pure RDF and doesn't require OWL.  OTOH it 
is a little less concise and less elegant than OWL Manchester.

But let's talk about URIs of single resources.  In the past I have 
always advocated the approach of treating them as OpenMath symbols, as, 
in fact, both are identified by URIs.

This "just" (and this question is unanswered so far) creates the problem 
that OpenMath prescribes a rather restricted URI syntax 
(cdbase/cd#name), whereas RDF allows pretty much any URI.

In many practical cases at least RDF hash URIs fit into the OpenMath 
scheme, but it's not always intuitive to enforce splitting them into 
OpenMath-style cdbase, cd and name components, and it does not always 
result in valid names.

Consider http://www.w3.org/1999/02/22-rdf-syntax-ns#type, which might 
end up as <OMS cdbase="http://www.w3.org/1999/02" cd="22-rdf-syntax-ns" 

It would be more idiomatic wrt. OpenMath to speak of <OMS 
cdbase="something" cd="rdf" name="type"/>.

In a non-standard extension (implemented as a part of the OMDoc 
language, which can be considered a superset of OpenMath) I have 
suggested binding CD names to RDF namespace URIs, i.e. here binding the 
"CD name" "rdf" to the namespace URI 
http://www.w3.org/1999/02/22-rdf-syntax-ns#.  For background see

   author = {Christoph Lange and Michael Kohlhase},
   title = {A Mathematical Approach to Ontology Authoring and 
   url = {http://kwarc.info/kohlhase/papers/mkm09-omdoc4onto.pdf},
   crossref = {MKM09},
   pages = {389--404},
   keywords = {conference,clange-phd},
   pubs = 
   year = {2009},
   month = jul,
   booktitle = {{MKM/Calculemus} Proceedings},
   title = {{MKM/Calculemus} Proceedings},
   editor = {Jacques Carette and Lucas Dixon and Sacerdoti Coen, Claudio 
and Stephen M. Watt},
   number = {5625},
   series = {LNAI},
   keywords = {conference},
   isbn = {978-3-642-02613-3},
   publisher = {Springer Verlag}}

but I wouldn't take the position of recommending this as a best practice 
for OM in general.  If we'd like to unify OpenMath and RDF URIs we need 
a different approach, and I have no idea what this could be.

And another final question is whether (and if so, how) your CD allows 
for representing complete RDF triples as OM objects – of maybe this is 
not intended after all.



Christoph Lange, Jacobs University Bremen
http://kwarc.info/clange, Skype duke4701

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