Re: Web Rule Language - WRL vs SWRL

Perhaps this should move to rdf-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 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.

>    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!

> 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. 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?

> 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.

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.

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. Why two stacks instead of 
twenty and how do you make those twenty talk *at all*?

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!)

Cheers,
Bijan.

Received on Wednesday, 22 June 2005 18:24:48 UTC