- From: Jim Hendler <hendler@cs.rpi.edu>
- Date: Wed, 7 Nov 2007 09:01:52 -0500
- To: OWL Working Group WG <public-owl-wg@w3.org>
- Cc: Jeremy Carroll <jjc@hpl.hp.com>, Sandro Hawke <sandro@w3.org>
I was thinking about whether this should be an actual issue or not, but decided to start it here - Depending how I interpret the current documents I can see this being anything from a null issue to a real re-chartering need, so I thought I better bring it up... History: if you look at the OWL Requirements and Use Cases [1], you will see that "Effective Decision Procedure" (define as decidability) is an Objective of the language, not a requirement. We may all have somewhat different memories of how we got to that, but basically, there was not consensus in the group at that point in time that every feature we would want in a Web Ontology Language would be decidable. As it turned out, this came to be important, and the case that really brought it to the fore was the issue of inverseFunctional datatypes. To make a long story short, the discussions around this issue almost scuttled the Working Group (I was on the phone with the W3C director several times to convince him to let us try to find a way around the impasse), and it was a compromise (brokered by Frank van Harmelen) which led to us having a restricted subset of the language, later called OWL DL, and an unrestricted one, which came to be called OWL Full. This distinction is not artificial - the issues that couldn't be resolved at that time, and some still can't, cause the split between the two branches of OWL, and there are clearly those on the AC, including myself (since i'm not chair and can have an opinion this time), who need and care about OWL Full. Issue: OK, now to the present - In the OWL 1.1 Web Ontology Language Submission [2], the background makes it very clear that OWL 1.1 arose because "an extension of OWL-DL was proposed." And, in fact, it turns out that the documents for OWL 1.1 do indeed include an extension to OWL DL, but it is unclear, and a real issue, as to how they treat OWL full. For example, in the BNF for OWL 1.1, the following is included: inverseFunctionalObjectProperty := 'InverseFunctionalObjectProperty' '(' { annotation } objectPropertyExpression ') but I can find no similar construct for inverseFunctionalDatatypeProperty - so in essence the OWL Full construct has been ignored completely. This could be simple to deal with - these omissions can be easily fixed when a section on OWL 1.1 Full is added to the document This could be a charter issue - since it very clearly contradicts the charter [3] statement that "All new features should have a clear syntax, and a clear semantics both in terms of OWL DL and OWL Full. The existing compatibility between OWL DL and OWL Full should be preserved, and should be extended to new features wherever possible." Impact: So, I'm hoping this will be explained as my misunderstanding of the new documents (which I admit I'm still having trouble working out the details of) and not a real issue. If I'm right, then I am afraid I'll need to oppose publication of the OWL 1.1 documents until something about this is added somewhere, since I think it would be a mistake for the WG to publish working drafts that are in violation of our charter -JH p.s. Please note I only discussed inversefunctionaldatatype, but the same goes for all the differentiators of Full vs. DL - and also for new features, cf. my email about Issue 8 which falls under extending OWL Full in the new feature (i.e. allowing a property chain to end in a datatype property should clearly be allowed in OWL 1.1 Full) p.p.s. Lest anyone mistake me - I am not claiming this is currently a charter violation, that would be a big step I'm not ready to take, rather I'm asking for clarity on this and on whether it is something the WG needs to take into consideration. [1] http://www.w3.org/TR/webont-req/ [2] http://www.webont.org/owl/1.1/ [3] http://www.w3.org/2007/06/OWLCharter.html (may be member readable only, I forget if charters are public)
Received on Wednesday, 7 November 2007 14:04:37 UTC