W3C home > Mailing lists > Public > public-sw-meaning@w3.org > October 2003

Thought experiments on a proposed solution

From: John Black <JohnBlack@deltek.com>
Date: Wed, 1 Oct 2003 15:42:27 -0400
Message-ID: <D3C8F903E7CC024C9DA6D900A60725D90258D46F@DLTKVMX1.ads.deltek.com>
To: <public-sw-meaning@w3.org>

I would like to propose the following solution to this 
issue.  We create a specification for the Semantic Web 
Conformity Relation (SWCR), a binary relation where each 
tuple contains one element from the set of all URIs and one 
element from the set of all classes defined in any ontology.  
The ontology element is specified either by the owner of the 
URI or by default.  This binary relation may be virtual 
and certainly will be decentralized, a federated creation 
of the combined efforts of every one who participates in 
the optional Semantic Web Conformity Protocol (SWCP).  

Now some thought experiments:
1) How does this relation get populated?
An RDF tag specifying the ontology:type of the URI is:
1.a) embedded in the document at that location. OR
1.b) is in an RDF document that embeds 
(wraps) the document found at that location, possibly with 
new mime type. OR
1.c) an MGET function is called on the URI which returns a
document containing the tag. OR
1.d) some form of redirection takes place and the document
at that location contains the tag. OR
1.e) some form of content negotiation takes place and 
locates a document containing the tag. OR
1.f) other solutions are possible. OR
1.g) all else fails, the URI defaults to type 
ontology:http-resource, which is a class in an ontology of 
the present hypertext web.

2) But what if the URI contains a hash mark?
One of the methods listed under number 1 will have to be 
applied to each such URI and performable from the URI with 
the hash mark removed.

3) What about RDDL?
Instead of putting the RDDL document at the endpoint of 
the URI, there would be an ontology:namespace tag there.  The 
actual location of the RDDL document would then be located 
according to the location method defined by that namespace 
class.  That definition could well say, look up the html 
document at that URI.  But this would no longer be necessary 
due to the level of indirection afforded by the SWCR.  If I 
want the type of the URI to be myOntology:myNamespace, then 
my definition may specify that the RDDL is located elsewhere.

4) How about Sandro's 4 RDF programmers requirements? in 
r1) All URIs are now logical constant terms with solid grounding 
in the sw, including those that have not been typed.  For those 
now constitute a large set of statements of the form "that http-resource".
Those URIs that have been typed by the owner have as simple or complex 
a meaning as the owner wants.  
r2) have a human readable web page - The class of the URI can be 
defined to point to such a page, along with an access method to it.
r3) a web address for RDF/XML content - Similar to r2, the class 
of the URI can have a Property giving the location of an RDF dump 
for any URI in that class, as well as a path to it.
r4) the address of a query answering service - Similar to r2,r3.
In general we use the power of this new technology to create classes 
of URI that will do whatever we want.

5) What does using an URI require of me and my software? as asked in 
You must look up a URI in the SWCR and make sure that your use of the 
URI conforms with the type as defined by the owner.  If molly wants to 
use sally:123 and abide by the optional Semantic Web Conformity Protocol 
(SWCP), then molly looks up X in SWCR(sally:123,X).  
Suppose X = domesticAnimals:cat, then molly can use sally:123 as a 
domesticAnimals:cat or a domesticAnimals:mammal or as a 
domesticAnimals:animateBeing.  But Molly will violate the optional SWCP 
if she uses sally123 as a domesticAnimals:dog. Lets say that Molly's 
reputation according to SWCP will move lower a notch, people will give 
her a lower SWCP-trust-rating.

6) How does this answer Tim's request in New Issue - Meaning of URIs in
RDF documents? as presented in 
6.1) It's a concise statement of a number of architectural elements.
By objectifying the requirements with the virtual SWCR, many goals 
are simply stated.
6.2  It gives guidance on some specific questions, such as what is 
a SWCP compliant tool required to do when using someone's URI - look 
it's meaning in the SWCR and conform to it.
6.3.a  It clarifies certain points.  URIs have a single meaning, that is,
the X in SWCR(URI,X).  It is the URI owner that puts the defining tag 
in the SWCR.  
6.3.b  Consistent misuse of a URI results in a lowering of the reputation 
of the misusers - not in a change of the meaning.
6.3.c  The use of a URI implies conformance to the SWCR as described. 
When in doubt you look it up in the SWCR as described above.
6.3.d  Setting the defining tag in under the control of whoever controls 
what is located at that URI.

John Black
Senior Software Architect
Deltek Systems, Inc.
13880 Dulles Corner Lane
Herndon, VA 20171
703-885-9646 - Office (Tues,Wed,Thur)
434-964-1936 - Home Office (Mon,Fri)
434-825-3765 - Mobile (Anytime)
Received on Wednesday, 1 October 2003 15:44:35 UTC

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