- From: Michael Kifer <kifer@cs.sunysb.edu>
- Date: Tue, 28 Jun 2005 15:17:33 -0400
- To: Ian Horrocks <horrocks@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>
Ian, The difference is really between SWRL and everything else, and SWRL should be developed by a different WG, if there is a need for a rules language sitting on top of OWL. N3 is essentially a different syntax for F-logic and its extensions (but N3's semantics is defined by use cases ;-). As far as I can tell, with each new presentation that I hear N3 is moving in the direction of LP. --michael Ian Horrocks wrote: > > On 23 Jun 2005, at 05:54, Michael Kifer wrote: > > > > > > > Jim, > > So, you are saying that LP is at the same stage as DAML+OIL before > > standardization. What is needed is to work out the details -- > > typically a > > job for a working group. Who disagrees with that? > > I do not agree that the current situation w.r.t. "rules languages" is > comparable to the one appertaining w.r.t. "ontology languages" when the > WebOnt working group was chartered. At that time there was a single > candidate ontology language around which a broad consensus had already > been built (e.g., through the merging of the OIL and DAML-Ont efforts). > Currently there are several competing rules language proposals, with no > obvious (to me) leading contender. > > I also disagree with the suggestion that a Working Group is likely to > be able to resolve major technical problems - if you look at what went > in to WebOnt (DAML+OIL) and what came out (OWL), you will see that they > are relatively similar. This is not to minimise the quality or quantity > of the work carried out within WebOnt - it simply illustrates how > difficult it is to get a large and heterogeneous WG to agree on > anything, never mind agreeing on significant technical changes, and how > much effort is required to go from a prototype to a finished product. > > So, your argument leads me to the conclusion that either (a) one of the > candidates should be (arbitrarily?) chosen for standardisation, (b) a > WG should be established without any clear indication as to what should > be standardised, or (c) several WG's should be established - one for > LP, one SWRL, one for N3, etc. Option (a) is hardly likely to promote > consensus building, option (b) seems to be a recipe for years of > unproductive argument, and option (c) would be very costly (for both > the W3C and the semantic web community), and very confusing for those > considering the adoption of semantic web technology. > > A fourth alternative, and one that I think several people in this > thread have been arguing for, is to continue working (in whatever > context) towards an architectural framework that provides for a better > integration between First Order and LP based languages. We should then > be able to achieve the broad consensus which is, I believe, a necessary > (or at least highly desirable) precursor to the initiation of a > standardisation activity. > > Regards, > > Ian > > > > > > > > And you didn't need to defend OWL because nobody was attacking it. Our > > discussion was about the 1-stack vs. multi-stack architectures. Since > > in a > > previous email you said that you are "not against a multi-stack > > solution" > > then I don't see what is the point of contention (at least at the high > > level). I believe that everybody agrees that the more integration -- > > the > > better. We just don't believe that integration of the leading useful > > technologies to the point that only one stack is left is possible. > > > > > > --michael > > > > > >> Mike - I think you're missing the point of the "webbie" nature of OWL > >> and the difference from traditional KR, but I have written that up > >> too many times to do it again here. With LP, the question is how I > >> can use your rules/program/etc. in part to get a "network effect" and > >> to make it so I can link together the logics and logic programs as > >> easily as I link web pages. It;s not that no one has good research > >> ideas on how to do that, it's how to bring those to fruition and > >> greater use that is the key > >> The ontology stuff in OWL, which is not actually DL (even OWL DL > >> departs from traditional DL in some interesting ways, but OWL Full is > >> the one I care most about) is based on many years of work in AI, and > >> was explored on the web long before OWL was done - cf the SHOE work > >> my group did (still a high hit at Google - so just google "shoe") and > >> that was followed by XOL, OIL, and others before the standardization > >> began. > >> I think the LP stuff is in similar state - a basic idea has been > >> fleshed out, some variants are being explored, and there is a govt > >> interest in pushing for a de facto standard. But going from there > >> to the finish line is where a lot of the time and blood goes in -- > >> it's in making the stuff fit with what else is out there in the Web. > >> We had to do a lot of work to make OWL fit in with RDF and other > >> languages it needed to interoperate with, and a web rules language > >> needs to be defined with the other things already in the space it > >> wants to play in (thus the "stacks" issue - if it wants to be in a > >> Sem Web stack, it needs to play with other SW stuff; if it wants to > >> be in the XML stack, it needs to play nice with XML stuff like Xquery > >> and Xpath, etc. > >> And that is the discussion we are having -- but if we can nail this > >> stuff, the result is worth it -- OWL is certainly the most used > >> KR/ontology langauge in the history of AI as best anyone can tell, > >> and if we want the Web Rules Language to flourish we want it to grow > >> like the Web does, not like rules languages have -- nothing wrong > >> with the latter, but there's a whole lot more Web pages out there > >> than logic programs, and it's a lot more fun to play in the > >> exponential growth space :-) > >> anyway, we're all working for same ends, just different means, and > >> finding the consensus space in the middle is wondefully non-fun, but > >> worth it in the end > >> > >> Ok, end of crap, back to technical issues and Greek symbols... > >> JH > >> p.s. please note - I spent many years of my career arguing against DL > >> and doing scruffy AI - yet here I am defending OWL - why? because > >> the design time and fights over the details of a number of use cases > >> ended up creating something pretty damn useful -- both in the OWL DL > >> space and in the OWL Full space -- so somehow the process worked... > >> > >> > >> At 20:41 -0400 6/22/05, 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. > >>> > >>>> 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 > >> > >> -- > >> Professor James Hendler Director > >> Joint Institute for Knowledge Discovery 301-405-2696 > >> UMIACS, Univ of Maryland 301-314-9734 (Fax) > >> College Park, MD 20742 http://www.cs.umd.edu/users/hendler > >> > > > > > > > >
Received on Tuesday, 28 June 2005 19:17:58 UTC