Re: [xml-dev] Meta-somethingorother (was the semantic web mega-permathread thing)

Michael Rys wrote:

> Once somebody shows me a description logic inference engine that 
> actually scales, I will become more interested in this aspect.

DL inferencing is relatively slow although boundedly so, however, for 
the types of problems it addresses, it may be a necessary cost at this 
stage of the game -- note that the DL dialect of OWL is selected 
because it is thought to be *faster* than the completely unconstrained 
RDF dialect of OWL: OWL Full.


> The one advantage RDF as any extended entity relationship model has 
> over tree models like XML, is the ability to represent relationship 
> graphs. However, for that, there is a very well suited tuple based 
> model: the relational model. Having more semantics associated with the 
> relationships is useful, but only as long as the relationships are 
> built-in.
>
> Best regards
>
> Michael (who in his former live implemented a hybrid 
> database/description logic system)


See that's exactly as I see it, and others have/are currently worked 
on/are working on/ this approach: a hybrid RDB inferencing approach. 
This is really what data mining applications *are*.

*The* big initial driver of OWL was DARPA, as it is well known that OWL 
was incarnated as the "DARPA Agent Markup Language" and it is well 
known that there is alot of interest in certain well-funded government 
circles regarding threat classification, pattern recognition. For 
example suppose we have gobs of random information, and from these gobs 
we have a way to correlate the information into individual collections, 
for example, suppose we can correlate a whole host of phone 
conversations as involving individuals. Now suppose we have lots of 
other types of information that involve other (as yet unnamed) 
individuals. What we want are a set of inferencing operations that will 
allow us to *equate* individuals identified by sets of phone 
conversations with individuals identified by financial transactions. 
Get the picture.

In OWL, these there the operations that the inferencing engine can spit 
out:

:Joe owl:sameIndividualAs _:1

where _:1 identifies a blank node.

formally known as graph merging, informally known as smooshing.

Now I can give similar examples from medical diagnosis.

In any case all of the above examples would typically run off of a 
relational db platform. DL is then seen as primarily a type of data 
mining operation.

There is more of course, OWL/RDF is web aware in the sense that all 
names are URIrefs, and so there is the capability of linking 
information across platforms. Now *iff* RDBMS had ever actually become 
platform independent there might not ever been a need to develop a new 
schema language -- e.g. you might have URIified SQL names and run your 
PIVOTS across machines in a transparent fashion, but the current state 
of RDBMS is hardly that. The more you encourage SQL developers to run 
C# code in the DB, the less you are using the relational model, the the 
point where tuples may become somewhat irrelevant. So from an entirely 
*practical* point of view RDBMS are not transparent to the Web. Oh 
well, that's life and business. It is very similar to the fact that 
genetic evolution is not always the most efficient but it is what it 
is. So goes the evolution of technology: If there are problems to be 
solved for which the current tools don't quite do the job, sometimes we 
write entirely new tools rather than adapt the ones we have, and then 
the old tools get rewritten with the new features etc.

See, you would have been a perfect person to serve as MS representative 
to WOWG if MS had chosen to get involved in that effort. Peter F. 
Patel-Schneider who did alot of the heavy lifting for OWL certainly has 
a fairly extensive knowledge of RDBMS.

Jonathan