RE: [OEP] Scope - (was philosophy of SWBPD (was Re: [OPEN] and/or [PORT] : a practical question))

Reasoning with inconsistency and changing information may be necessary
for the success of the Semantic Web, but has proven extremely difficult
to crack, from an automated reasoning perspective in the researchy
community. If there is no reasoning being done, then why is there a need
for a language like OWL?
Is there enough experience to report on best practice on these
Web-specific issues?

    * Ability to be distributed across many systems
    * Scalable to Web needs
    * Compatible with Web standards for accessibility and
    * Open and extensible
The issue of handling ontologies which are build by linking to and
importing other ontologies is an important one. There are are a lot of
challenging research issues there, is there any best practice?
Whether something is research or practice is orthogonal to whether it is
related to the Semantic Web. The latter was the point I was addressing.
I agree that this WG will struggle with this important [former] issue.
-----Original Message-----
[]On Behalf Of Jim Hendler
Sent: Monday, April 05, 2004 2:09 PM
To: Uschold, Michael F; Bernard Vatant; SWBPD
Subject: RE: [OEP] Scope - (was philosophy of SWBPD (was Re: [OPEN]
and/or [PORT] : a practical question))
At 12:52 -0700 4/5/04, Uschold, Michael F wrote:
> -----Original Message-----
>From:  Jim Hendler []
>Ahhh - the root of a lot of our disagreements becomes clear -- in my
>world view, reasoners are not likley to be a major force on the Sem
>Web, and those that are are not likely to last very long if they
>cannot handle inconsistency -- I won't make the argument here, I've
>done it lots of times in many other forums and in print (see my talk
>at ISWC last year [1] for one example) -- thus, I think that the
>claim "being able to prove anything at all" is clearly just plain
>ridiculous for any tool that has any chance of working on the Web.

><MFU: are you sayng that the the logicians claim that inconsistency
enables a reasoner to prove anything is not relevant in the  context of
the Web?  If so, that might be true, and argues for not worrying about
consistency. If not, then I don't know what you are saying. I cannot
parse it into English that I understand, because "being able to prove
anything at all" is not a claim, per se it is a just a sentence
I'm claiming that pragmatically we'd better learn to deal with it ---
consider, if I publish a document that says:
I am male.
I am female.
Male and female are disjoint classes.
You owe me a thousand dollars
and your reasoner sends me the money, then I don't think you'll be in
business very long.   More seriously, the problem is that the
inconsistency can (and I argue will) arise from many sources --
accidental (you type 5 and I type 55 when we mean to say the same
number), conflicting views (see if you can get right to lifers and
abortion proponents to agree on what "birth" is), and from maliciousness
- as in the case above, if I can fool your reasoner into making wrong
conclusions, I have a whole new kind of net attack to explore.  There's
many ways to deal with these kinds of inconsistencies, but note that the
key is that we will have to deal with them somehow...

>So in that light, I have no objection to consistent stuff, I just
>don't see it as the single most important thing to always worry
>about...   but notice Mike, we' ve just turned this into a trade-off
>discussion - so where you said we sometimes have to take sides, I
>just basically think this is harder than you think....
>I doubt I could agree to this - I have no idea what "all other things
>being equal" means in a dynamic changing system like the Web.
><MFU: I mean something very simple. You are building an ontology for a
specific application. You have a very simlilar notion come up in several
circumstances and there are several ways to represent this notion. If
you represent the same notion in several different ways for no reason,
then it is likely to confuse people trying to understand and use the
ontology. They will keep wondering: did he do it all these different
ways for a reason? It would be simpler and more perspicous to do them
all the same way.  
ok, I'll grant you that within a single ontology DOCUMENT (I won't get
into a fight now about how you define what an ontology is when they are
linked to others and include some imports) it probably makes sense to
define things in a straightforward way and to document disparity from
that ...
>In case anyone hasn't figured it out by now - I THINK IT SHOULD BE
>Working Group.  If you'd like me to state it clearer, let me know
>what to addd
><MFU For starters, it will be necessary to give clear criteria for
determining whether something is or is not "related to the Semantic
Web". Next it would be very helpful to apply those criteria for several
examples where we can all see that aha, this ontology engineering
guideline is clearly not related to the Semantic Web, but those are. 
>I would be surprised if it was possible to do this. As it is, for
example, some of the papers in the first issue of the new Journal of Web
Semantics don't have much if any specific relevance to the Web, semantic
or otherwise. Yet, they address important ideas that CAN are are LIKELY
to be applied to the Semantic Web.  And so, they were deemed appropriate
for the journal.  Analogously, many/most ontology engineering guidelines
that we may come up with that are illustrated with OWL are likely to be
used by people building ontologies for use in the Semantic Web. The fact
that they are illustrated with OWL although  key in one sense, is quite
irrelevant with respect to the underlying OE guideline, which could be
expressed in many different ontology/KR languages.
Now you finally get to the crux, although backwards in a way -- Web
Semantic is a RESEARCH journal -- but read the W3C process documents and
our charter and you'll see that WGs do NOT so research -- this was
always a challenge in the OWL WG, and will be one for this WG as well
>Yes, but it wouldn't be a SEMANTIC WEB langauge, and thus I would
>argue (see above) this WG should not spend time discussing it
>They ARE central to the design of OWL, in the sense that OWL is
>specifically FOR the Web, and thus had to have a few things that
>typical KR/O languages lack.
>Yes, and strangely, this makes them SIGNIFICANTLY new and different,
>and this WG, being part of the W3C SEMANTIC WEB activity should
>primarily be concerned with the new aspects.
><MFU: Following on from above, perhaps you can clearly state exactly
what the {Semantic Web}-specific parts are and give some examples of
some guidelines that are useful and specifically focus on these new
I can name that tune in one line:
 It is the use of RDF as the basis for the language, allowing linking
between separately created ontologies.  
In fact, I don't even have to make this up -- here's what it says in the
OWL FAQ [1]:
Q. How is OWL different from earlier ontology languages?

A. OWL is a Web Ontology language. Where earlier languages have been
used to develop tools and ontologies for specific user communities
(particularly in the sciences and in company-specific e-commerce
applications), they were not defined to be compatible with the
architecture of the World Wide Web in general, and the Semantic Web in

OWL rectifies this by providing a language which uses the linking
provided by RDF to add the following capabilities to ontologies:

    * Ability to be distributed across many systems
    * Scalable to Web needs
    * Compatible with Web standards for accessibility and
    * Open and extensible
so I think if we stick to best practices that draw from these four key
capabilities (arrived at with great work, and signed off on by the
members of the W3C)
Professor James Hendler 
Director, Semantic Web and Agent Technologies       301-405-2696
Maryland Information and Network Dynamics Lab.      301-405-6707 (Fax)
Univ of Maryland, College Park, MD 20742      240-277-3388 (Cell)

Received on Monday, 5 April 2004 20:50:22 UTC