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Re: Web Rule Language - WRL vs SWRL

From: Michael Kifer <kifer@cs.sunysb.edu>
Date: Wed, 22 Jun 2005 19:55:33 -0400
To: Bijan Parsia <bparsia@isr.umd.edu>
Cc: www-rdf-logic@w3.org, public-sws-ig <public-sws-ig@w3.org>, www-rdf-rules@w3.org
Message-Id: <20050622235534.5FB8119E75F@kiferdesk.lmc.cs.sunysb.edu>


Bijan,

It looks like we agree about almost everything, and I am afraid that
this thread is loosing its entertainment value. :-)
I just want to comment on one of your points:

> The question is on the integration. Do we know enough to design an 
> integrated solution. If you look at my rules workshop position paper, I 
> argue for integration, but I don't think we're quite there yet 
> technically. Hence, I'd like to wait a bit.

I think the (nonmonotonic) rule-based side of the stack is very mature (I
dare say more mature than the "other" side :-) and if W3 doesn't do it
then somebody else will. There is a good story about minimal integration
using the black-box architecture, and this is very appropriate for
standardization.


	--michael  


> On Jun 22, 2005, at 3:49 PM, Michael Kifer wrote:
> 
> > Bijan Parsia wrote:
> >>
> >> Perhaps this should move to rdf-rules?
> >
> > Perhaps.
> 
> CCing rdf-logic and rules.
> 
> >> On Jun 22, 2005, at 11:29 AM, Michael Kifer wrote:
> >>
> >>> Bijan Parsia wrote:
> >> [snip]
> >>>> To extend the conversation in another direction, is there any reason
> >>>> to think
> >>>> that a logic programming paradigm, in general, is the right approach
> >>>> to nonmon
> >>>> on the Web? Representationally? There are many non-monontonic
> >>>> formalisms
> >>>> (consider default logic and autoepistemic logic) and it might be 
> >>>> that
> >>>> they 1) are
> >>>> better for web contexts and 2) play better with owl. (It's 
> >>>> plausible,
> >>>> for example,
> >>>> to think that default logic can be made to fit better because of the
> >>>> separatation
> >>>> of the base representation and the default rules. Even there,
> >>>> adjustements must
> >>>> be made.)
> >>>>
> >>>> (Of course, anything in this space runs into the problem that, in
> >>>> general,
> >>>> nonmon formalism are much more computationally difficult than
> >>>> corresponding
> >>>> monotonic ones. The LP position often appeals to the
> >>>> scalablility/computational
> >>>> goodness of, say, deductive databases. But if that comes at the 
> >>>> price
> >>>> of
> >>>> throttling back expressivity forever...maybe it's not such a great
> >>>> idea. Pat Hayes
> >>>> often, to my understand this, as thinking of nonmon constructs as
> >>>> part of the
> >>>> *data* on the web (to his mind, bad), and nonmon as a way of
> >>>> *reasoning with*
> >>>> the data on the web (good...it's located in the agent or processor
> >>>> which is in a
> >>>> position to make certain assumptions with a good sense of the 
> >>>> risks)).
> >>>
> >>> These are all valid points for future research.
> >>
> >> That's the extension of the conversation I'm after.
> >
> > I think it is a research program. I don't think much, if anything, can 
> > be
> > accomplished on a mailing list.
> 
> Well, if we were trying to accomplish much, we wouldn't have gotten 
> engaged in the first place :)
> 
> A lot depends on whether you think "KR on the web" is fundamentally 
> different than off it. A lot also depends on how much you think those 
> issues affect or should affect standardization effort.
> 
> >>> I believe, however, that
> >>>
> >>> 1. It is naive to assume that one single formalism like DL or LP 
> >>> would
> >>>    serve the humankind forever.
> >>
> >> I certainly don't think that.
> >
> > Good!
> >
> >
> >>>    The architecture should provide for multiple formalisms (where the
> >>>    formalism would be identified together with the statements -- 
> >>> RuleML
> >>>    attempts to do something like that).  The communicating parties 
> >>> will
> >>>    either be able to talk (if they both understand that particular
> >>> formalism)
> >>>    or they won't, but at least they will know it.
> >>>    Certain degree of interoperability between the different 
> >>> formalisms
> >>> can
> >>>    be provided without them being built on top of each other.
> >>
> >> This is going in a different direction, which I'm sympathetic too. But
> >> it seems to end up in the land of multiagent systems (with agents
> >> wrapping and mediating different data sources). That *doesn't* seem
> >> like the semantic web as I've heard it articulated.
> >>
> >> Maybe the semantic web as such is impossible!
> >
> >
> > I don't know what "semantic web as such" is, but I do believe that
> > defining it as a single stack is doomed to fail.
> >
> >
> >>> 2. Regarding the suitability of LP, this is backed by over 30 years 
> >>> of
> >>>    practice.
> >>
> >> Hmm. Yes and no, right? The question is suitability *for what*. Of
> >> course, we're all groping in the dark, really.
> >
> > LP has been used for knowledge-intensive apps for as long as I stated.
> > Webby things are not that different -- just another application.  
> > There are
> > interesting problems for sure, but it is funny to watch some of the
> > discussions in which people create fetishes and pray to the god of 
> > URLs.
> >
> >> The W3C made a bet
> >> though that is not easily reconcilable with LP (and components of
> >> which, at least, have similar depth in background). So, do we zig? 
> >> Zag?
> >> Stay the course? Stay mostly the course? Start over?
> >
> > So, they erected one stack - this is fine. If they will insist that 
> > this is
> > the one and only true stack, then the thing is going to die due to
> > irrelevance.
> >
> >
> >>> Default logic is nice, but it is just a theoretical tool at
> >>>    this point. Before it (or its derivatives) can make into a Web
> >>> standard,
> >>>    I suggest to give it a try (or **practical** use) for, say, 10
> >>> years by a
> >>>    reasonably sized user community.
> >>
> >> While that would be my general suggestion for *EVERYTHING* :), betting
> >> seems to be the name of the game.
> >
> > See, organizations like OASIS let their standards to die. If W3C is 
> > fine
> > with that then they can bet all they want.
> > But it seems to me that W3C is not prepared to kill its own standards, 
> > and
> > in this case it should bet very carefully and with an eye on the 
> > future.
> >
> >>
> >> Looking at LP land, I don't see systems doing the "Web" thing. Of
> >> course, I'm not entirely sure what the web thing *is* really. I'd love
> >> to have better clarity on that so we could figure out what really
> >> *should* be going on.
> >
> > Exactly. What is the "Web" thing precisely?
> > If you view it as a large distributed KB then LP is arguably doing 
> > this.
> >
> >
> >> However, and I think it's a reasonable position, you are actually
> >> advocated a non-integration strategy. (As you said in one.) That's
> >> fine, but then I would like it if those cards were laid on the table
> >> instead of claims of integration, overlap, compatibility (let me note
> >> that you are not the one making such claims). Let's change the 
> >> freaking
> >> architecture to a hub and spoke, or whatever.
> >
> > As I said, it is presumptuous to claim that the current technology will
> > remain true for all times -- even for 5 years from now.  A realistic
> > architecture should allow for more spokes.
> >
> >> Why two stacks instead of
> >> twenty and how do you make those twenty talk *at all*?
> >
> > One way for them to talk is to allow them to view each other as black 
> > boxes
> > and send queries to each other. This is essentially the architecture of
> > AL-Log.
> 
> Yes.
> 
> > The Eiter et all. papers that you cite in your paper take the same
> > approach and try to integrate DL with LP a bit tighter.
> 
> Well, similar approaches.
> 
> > It is strange that you even cite Eiter's paper because, if anything, 
> > this
> > paper is an argument that a single stack is a bad idea and that 
> > several,
> > loosely integrated, stacks is a way to go.
> 
> The question is on the integration. Do we know enough to design an 
> integrated solution. If you look at my rules workshop position paper, I 
> argue for integration, but I don't think we're quite there yet 
> technically. Hence, I'd like to wait a bit.
> 
> >> This is close to the RuleML view of things. I've watched RuleML for
> >> quite a while and I still believe that its approach, while appeal, is
> >> not the kind of thing that the W3C likes to do. They like to pick
> >> winners, rather than pick integration formats. (Of course, they like
> >> picking winners at the "right" level...XML is pitched, after all, as 
> >> an
> >> integration format!)
> >
> > Winners? How do they determine who the winner is?
> 
> It's all magic. *Web* magic :)
> 
> >  (The rest of the diatribe
> > is not for a public list :-)
> 
> Such diatribes are *best* on a public list :)
> 
> Cheers,
> Bijan.
> 
> 
Received on Wednesday, 22 June 2005 23:55:50 GMT

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