W3C home > Mailing lists > Public > www-rdf-rules@w3.org > June 2005

Re: Web Rule Language - WRL vs SWRL

From: Bijan Parsia <bparsia@isr.umd.edu>
Date: Wed, 22 Jun 2005 17:18:17 -0400
Message-Id: <67e79f94a640a8cf26283d01594d6c6e@isr.umd.edu>
Cc: www-rdf-logic@w3.org, public-sws-ig <public-sws-ig@w3.org>, www-rdf-rules@w3.org
To: Michael Kifer <kifer@cs.sunysb.edu>

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 21:18:15 GMT

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