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Re: A thought on fragments and rec-track

From: Carsten Lutz <clu@tcs.inf.tu-dresden.de>
Date: Fri, 15 Feb 2008 09:08:45 +0100 (CET)
To: Jim Hendler <hendler@cs.rpi.edu>
Cc: public-owl-wg@w3.org
Message-id: <Pine.LNX.4.64.0802150904340.8936@frege.inf.tu-dresden.de>


I agree with what you say. Regarding OWL 1.0 Lite, there are
surely a number of things to be sorted out. However, this is maybe
also a slightly separate issue from the remainder of my proposal. I
did not mean to say that we should "invalidate" OWL Lite and take it
off-rec retrospectively. I only think we should find a (clean) way to
not devote significantly long parts of the OWL 1.1 rec docs to this


On Thu, 14 Feb 2008, Jim Hendler wrote:
> I think Carsten may be onto something - a couple of quick responses
> 1 - I think OWL DL and OWL RDF (whether by that name or not) works, and just 
> as in OWL 1.0 we tried to keep these in line, but not identical, I think that 
> would be the win strategy here as well (i.e. the "vocabulary" should be 
> releatively consistent, and the semantics wants to correspond as best it can 
> to the "natural" meaning of this vocabulary -- that's not meant to be obscure 
> - I just mean we try to use mnemonic names that correspond to the 
> formalization)
> 2 - I think the "OWL DL minus" and the "OWL Full minus" should also be made 
> to correspond to some degree, but I agree w/Carsten that keeping them 
> identical is less important - I think a lot of the constructs we want in each 
> would map well, so I don't think this would be so hard.
> 3 - I agree having a note, not a rec, that defines useful properties of 
> particular language restrictions in DL would be very useful (note: this would 
> be more or less our current fragments document renamed in some way to 
> disambiguate the idea of fragments in the rec from useful things for 
> implementors to know, in the note)
> 4 - The one place I think there is a problem w/the below is with the current 
> OWL Lite.  We cannot "take it off the rec track" - it is already a W3C Rec 
> for better or worse.  To understand this, think of RDFS instead of OWL Lite 
> -- we could suggest adding some things to RDFS, we could suggest some clean 
> up (backward compatible) of RDFS syntax or semantics, but we couldn't say "no 
> one use RDFS anymore" -- OWL Lite has exactly the same status (with respect 
> to W3C and the outside world) as RDFS (or OWL DL or Full for that matter) - 
> so our hands are a bit more tied with respect to that.   I think that the 
> solution Alan was thinking of - doing the minimum to keep the currently 
> defined LITE consistent w/the new recs, would work here -- basically, we 
> would be suggesting, implicitely that the new OWL DL minus and OWL Full minus 
> are better replacements for Lite and the Full-version-of-Lite (whih is not 
> actually a rec, but some people refer to in talks and documents) - and we'd 
> be able to better motivate them.   But as best I understand the world, Sandro 
> and Ivan correct me if I'm wrong, if we say nothing at all about OWL Lite, 
> then it remains a Rec exactly as it is - so it would be the "fifth" fragment 
> (but less compatible) than if we actually clean it up, but motivate the new 
> ones better
> I hope that makes sense, some of these things are hard to word right -- just 
> in case anyone is unsure:
> Summary: I like Carsten's idea, and am just puttering around the edges to 
> make it more consistent with the outside world that I interact with.
> -JH
> On Feb 14, 2008, at 2:55 AM, Carsten Lutz wrote:
>> Dear WG,
>> yesterday's discussion on fragments and rec-track showed once more
>> that, simplifying a lot, the WG is split into two groups. Let's call
>> them the RDF group and the DL group. Each of them has its own view and
>> valid arguments that support it. I believe that neither the WG nor the
>> two groups benefit from a confrontative way of dealing with this
>> situation.  Instead, we should try to have peaceful coexistence
>> whenever possible. Here is a simple way how this could be achieved for
>> the fragments/rec-track issue:
>> - We give OWL Full a rule-based semantics (it seems likely to me that
>> this will be decided anyway)
>> - Then, there are two fragments in rec-track: one OWL-Full fragment
>> (for the RDF group) and one OWL-DL fragment (for the DL group)
>> So we have : OWL Full, OWL Full Minus , OWL DL, OWL DL Minus
>> Never mind the naming scheme (IMHO, we should even rename OWL Full
>> to OWL RDF).
>> - As OWL-Full Minus, we choose OWL Prime. Unless I overlook something,
>> it is easily defined as a fragment of OWL-Full. Here, "fragment" means
>> that it selects two things: a) a subset of the OWL-Full vocabulary
>> and b) a subset of the OWL-Full semantic rules.
>> This means that we do not need Boris' bright but complicated
>> construction to capture OWL Prime as a syntactic fragment of OWL DL.
>> Neither do we need conformance  levels (but we could still have them
>> if we want).
>> - As OWL DL Minus, we choose a real *syntactic* fragment, as this is what
>> the DL group seems to imagine. I think this must be EL++, and am
>> happy to again provide motivation for why this is the case, and what
>> are the serious and commercial applications. But in general, that's
>> another issue.
>> - All the other fragments also remain, but don't go into rec-track.
>> greetings,
>> 		Carsten
>> PS: As for OWL 1.0 Lite, I suggest that we don't make it rec-track any-
>>   more, but explain in rec-track why this is the case and that OWL 1.0
>>   Lite users are now simply OWL 1.1 DL users, and thus fully supported.
>>   This is what I understood Alan was proposing. I don't view the issue
>>   of punning as problematic.
>> --
>> *      Carsten Lutz, Institut f"ur Theoretische Informatik, TU Dresden 
>> *
>> *     Office phone:++49 351 46339171   mailto:lutz@tcs.inf.tu-dresden.de 
>> *
> "If we knew what we were doing, it wouldn't be called research, would it?." - 
> Albert Einstein
> Prof James Hendler 
> http://www.cs.rpi.edu/~hendler
> Tetherless World Constellation Chair
> Computer Science Dept
> Rensselaer Polytechnic Institute, Troy NY 12180

*      Carsten Lutz, Institut f"ur Theoretische Informatik, TU Dresden       *
*     Office phone:++49 351 46339171   mailto:lutz@tcs.inf.tu-dresden.de     *
Received on Friday, 15 February 2008 08:08:58 UTC

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