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Re: Web Rule Language - WRL vs SWRL

From: Michael Kifer <kifer@cs.sunysb.edu>
Date: Wed, 22 Jun 2005 20:41:27 -0400
To: Jim Hendler <hendler@cs.umd.edu>
Cc: Bijan Parsia <bparsia@isr.umd.edu>, www-rdf-rules@w3.org, dreer@fh-furtwangen.de, Jos de Bruijn <jos.debruijn@deri.org>
Message-Id: <20050623004128.5ABCA19E75F@kiferdesk.lmc.cs.sunysb.edu>

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.

>   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.


>   -JH
> [1] http://www.w3.org/2003/08/owlfaq.html
> [2] 
> http://www.sciam.com/article.cfm?articleID=00048144-10D2-1C70-84A9809EC588EF21
Received on Thursday, 23 June 2005 00:43:08 UTC

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