While exploring the Subject Headings Linked Data Space (LCSH)
recently unveiled by the Library of Congress, I noticed that the
URI for the subject heading: World Wide Web, exposes an "owl:sameAs" link
to resource URI: "info:lc/authorities/sh95000541" -- in fact, a
URI.URN that isn't HTTP protocol scheme based.
The observations above triggered a discussion thread on Twitter that
involved: @edsu, @iand, and moi.
Naturally, it morphed into a live demonstration of: human vs
machine, interpretation of claims expressed in the RDF graph.
It showcases (in Man vs Machine style) the issue of
unambiguously discerning the meaning of the owl:sameAs claim
expressed in the LCSH Linked Data Space.
From the Linked Data perspective, it may spook a few people to
see owl:sameAs values such as: "info:lc/authorities/sh95000541",
that cannot be de-referenced using HTTP.
It may confuse a few people or user agents that see URI
de-referencing as not necessarily HTTP specific, thereby attempting
to de-reference the URI.URN on the assumption that it's associated
with a "handle system", for instance.
It may even confuse RDFizer / RDFization middleware that use
owl:sameAs as a data
provider attribution mechanism via hint/nudge URI values derived
from original content / data URI.URLs that de-reference to nothing
e.g., an original resource URI.URL plus "#this" which produces URI.URN-URL
-- think of this pattern as "owl:shameAs" in a sense :-)
Simply bring OWL reasoning (inference rules and reasoners) into
the mix, thereby negating human dialogue about interpretation which
ultimately unveils a mesh of orthogonal view points. Remember, OWL
is all about infrastructure that ultimately enables you to express
yourself clearly i.e., say what you mean, and mean what you
The SPARQL queries against the Graph generated and
automatically populated by the Sponger reveal -- without human
intervention-- that: "info:lc/authorities/sh95000541", is just an
alternative name for < xmlns="http" id.loc.gov="id.loc.gov"
concept="concept">, and that the graph produced by LCSH is
self-describing enough for an OWL reasoner to figure this all out
courtesy of the owl:sameAs property :-).
Hopefully, this post also provides a simple example of how
OWL facilitates "Reasonable Linked Data".
About this entry:
Author: Kingsley Uyi Idehen
Published: 05/05/2009 13:53 GMT-0500
Modified: 05/06/2009 14:26 GMT-0500
Tags: rdf , linked_data , semanticweb , web30 , sparql , virtuoso , DataSpace
Categories: Demos , Virtual Database , Semantic Web
Comment Status: 0