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Re: Web Rule Language - WRL vs SWRL

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Tue, 28 Jun 2005 13:09:02 +0100
Message-Id: <235d53927a4cd98f85d137b63836d152@cs.man.ac.uk>
Cc: Bijan Parsia <bparsia@isr.umd.edu>, Jim Hendler <hendler@cs.umd.edu>, www-rdf-rules@w3.org, dreer@fh-furtwangen.de, Jos de Bruijn <jos.debruijn@deri.org>
To: Michael Kifer <kifer@cs.sunysb.edu>

On 23 Jun 2005, at 01:41, Michael Kifer wrote:

>
>
> Jim Hendler wrote:
>>
>> Mike - I think you misunderstand the stuff about stacks and etc -- I
>> hope my use cases (in public-sws-ig@w3.org for those just joining the
>> conversation) would help make it clear that these are not separate
>> and unrelated stacks, nor are they identical things -- the key is
>> figuring out how the stacking works and how things interact -- I'm
>> not against a "multi-stack: solution, but as far as I am concerned
>> the more overlap the better, and I am fairly sure that we can do
>> significantly better than DLP in terms of providing a useful web
>> rules language that interacts well with the existing, and becoming
>> more widely used, ontology spec.*
>
> I think it is not just me, but a number of people who read your paper  
> on
> the two stacks may have misunderstood it. At least one way to  
> understand
> what is said there is that 1 stack is good and 2 is not.
> If there is another way to understand it (as advocating a multi-stack
> architecture) then this second meaning is deeper than I was able to  
> dig up.

Speaking for myself (and not necessarily for my co-authors) I would say  
that the main point of the paper is to explode the interoperability  
myth being presented in the so-called "updated layer cake"; a secondary  
argument was to the effect that trying to maximise interoperability  
between different languages is surely a desirable goal.

For the second point, many of us believe that it is possible to do  
something better than developing parallel LP and First Order based  
semantic webs, with little or no semantic interoperability. For the  
first point, if we are going to accept the parallel languages approach,  
then we should do so on the basis of a clear understanding of the (lack  
of) interoperability that can be expected. To be fair, as I understand  
your arguments, you are simply willing to accept having two (or more)  
semantically incompatible languages.

Regards,

Ian



>
>>   Seems to me the key is exploring how to get maximum interoperability
>> between the important work in BOTH areas (and I defy you to go back
>> through this discussion and find any email where I haven't said I'm
>> in favor of a web rules language)
>
> You didn't say this and I didn't say that you said this.  I was
> focusing on what I think were technically inaccurate claims in your  
> email
> regarding the layering of WRL on top of DLP (where WRL is taken to  
> mean the
> particular language under this name and not "a" generic web rules  
> language).
>
>> and also how to get the Web rules
>> to join in the growing whole that is the semantic web -- it's not the
>> same as applying LP in the Web area -- I argued for nearly a decade
>> about the difference between Web Ontology and standard AI KR
>> languages, and OWL has some significant differences from traditional
>> AI (see the OWL FAQ [1] and the discussion of KR  back in the 2001
>> Scientific American article [2])
>
> Not "applying LP in the Web area" but "adapting LP to the Web".
> Technically, OWL is an adaptation of DL to the Web with some additional
> research needed to accommodate RDFS.  But in the LP area this research  
> has
> already been done years ago.
>
>> This latter, btw, explains why URIs
>> are not just some wildassed thing, they're crucial to the Semantic
>> Web in a very deep way - read the Sci Am or any of Tim's discussions
>> of this issue.
>
> Of course URIs are crucial. After all, they are object identifiers, so  
> they
> are as crucial as any notion of an Id.
>
> But do they imply/require a new kind of KR?  There are interesting new
> problems that stem from the architecture, but don't make it sound as  
> if the
> "old KR" is out of the window and adapting it to the new architecture  
> is a
> hard or pointless exercise. The LP paradigm is as applicable to the  
> Web as
> DL, if not more. (I, of course, think that it is more :-)
>
>
>>   so, I don't see this as in any way being a discussion of rules vs.
>> ontology -- in fact, I cannot think of any dumber way to approach it
>> -- rather it seems to me we're trying to explore where these things  
>> can overlap to the benefit of users and of the Web -- that strikes me
>> as a very worthwhile pursuit
>
> The term "rules" is ambiguous in the context of our discussion. If you  
> said
> "I don't see this as in any way being a discussion of *LP* vs.  
> ontology"
> then this is exactly what I was trying to say. As I remarked above,
> the 2tower paper **appears** to be arguing that LP+OWL in a 2-stack
> architecture is a nonstarter.
>
>
> 	--michael
>
>
>>   -JH
>>
>>
>> [1] http://www.w3.org/2003/08/owlfaq.html
>> [2]
>> http://www.sciam.com/article.cfm?articleID=00048144-10D2-1C70 
>> -84A9809EC588EF21
>
Received on Tuesday, 28 June 2005 12:09:12 GMT

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