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

 -----Original Message-----
From: 	Jim Hendler [] 
Sent:	Wednesday, March 31, 2004 12:03 PM
To:	Uschold, Michael F; Bernard Vatant; SWBPD
Subject:	RE: philosophy of SWBPD (was Re: [OPEN] and/or [PORT] : a  practical question)


>MFU> Fine, so if you argue that in come cases you want or need 
>inconsistency and it is backed up with practical examples, then by 
>all means let users know that. If users can live with the 
>consequences of being able to prove anything at all, in return for 
>being able to do what they need, then they should be so informed. If 
>users requirements are such than they can get the job done and also 
>have a logically consistent representation, then there is a good 
>chance that it is  going to better serve them than an inconsistent 
>one, all other things being equal.

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 fragment.

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....


>>4. similar things should be modeled similarly, this also helps perspecuity.
>I think similar things should be modeled differently when used for
>different purposes -
>MFU: no disagreement there, I failed to state an implicit 
>asusmption: all other things being equal. Perhaps we can agree that 
>in general, it is confusing to represent similar things differently 
>if there is no good reason to do so?

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.   

>Look - my goal here isn't to be difficult -- it's to remind everyone
>that we are not writing up "AI Ontology" Best Practices.  We're
>writing up SEMANTIC WEB best practices, and we're still very early in
>that game, largely making it up as we go along.
>MFU: you have a point. The discussion has mostly been about Ontology 
>Engineering (not too surprising given the title of the working 
>group) and not specific to the Semantic Web. The implicit assumption 
>is that ontologies are a foundation for the Semantic Web, so it 
>makes sense to build them to that they best serve their intended 
>purpose.   If you can think of things that should be out of scope 
>for this TF because they do not explicitly address the Semantic Web, 
>ithen say so.

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. 

>Let's focus on sharing the things we're learning from applying RDF
>and OWL, not from the previous years of other languages -- they are
>simply not the same
>MFU: this is a suprising claim, given that the core of OWL is 
>basically no more different than any other knowledge/ontology 
>language than any of them are different from each other.  There are 
>some key things that make OWL appropriate for the Web (e.g. URIs), 
>but these are not central to the language in the sense that you can 
>easly remove them and be left with a fully functioning KR/ONTOLOGY 

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 things.
 For all the other 
stuff, we can point them at entire books full of decriptions of best 
practices, and I don't see why we would waste our time as a Working 
Group replicating 50 years of AI work

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 15:54:31 UTC