- From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
- Date: Wed, 24 Sep 2008 12:26:36 -0400 (EDT)
- To: alanruttenberg@gmail.com
- Cc: public-owl-wg@w3.org
Huh? What is this, and how would it be done. peter From: "Alan Ruttenberg" <alanruttenberg@gmail.com> Subject: Re: wording on Unknown returns in Conformance Date: Wed, 24 Sep 2008 12:17:07 -0400 > I had thought that it might be worth distinguishing distinct levels of > conformance - complete versus incomplete. Do you think that would be a > good idea? It bothers me a bit that conformance as specified for OWL > Full, as stated now, is not known to be possible. > -Alan > > > On Wed, Sep 24, 2008 at 10:04 AM, Peter F. Patel-Schneider > <pfps@research.bell-labs.com> wrote: > > > > There have been some comments on the "should not" wording in the > > conformance part of the Test and Conformance document. > > > > The current wording includes > > > > An OWL 2 Full entailment checker is an OWL 2 entailment checker that > > takes RDF documents as input, and uses the RDF-Based Semantics [OWL 2 > > RDF-Based Semantics]. It MUST return True only when O1 entails O2, and > > it MUST return False only when O1 does not entail O2. It SHOULD NOT > > return Unknown. > > > > Without the last sentence, a trivial checker, i.e., one that always > > returned "Unknown" would be just as good an OWL 2 Full entailment > > checker as one that tried hard. > > > > Even worse, if the last sentence was removed from > > > > An OWL 2 DL entailment checker is an OWL 2 entailment checker that > > takes OWL 2 DL ontology documents as input, and uses the Model > > Theoretic Semantics [OWL 2 Semantics]. It MUST return True only when > > O1 entails O2, and it MUST return False only when O1 does not entail > > O2. It SHOULD NOT return Unknown. > > > > then a trivial checker would be just as good as a complete reasoner for > > OWL 2 DL. > > > > > > I thus feel that there needs to be some wording in the conformance > > document to show that trivial checkers, or unnecessarily incomplete > > checkers, are not as good as ones that return "Unknown" in fewer cases. > > > > Remember that "should not" is not the same as "must not". A checker > > could return "Unknown" if > > 1/ it ran out of resources (memory, time, etc.); or > > 2/ it is an incomplete reasoner (for OWL 2 Full, for example, or even > > for OWL 2 DL). > > The above reasons (or others) could be used by entailment checkers to > > provide a justification for "Unknown" answers. I feel, however, that > > this is outside the scope of the specification. > > > > Perhaps it would be useful to add some wording on justifying "Unknown" > > to the document, but I think that most of this is implied by the use of > > "should not". > > > > peter > > > >
Received on Wednesday, 24 September 2008 16:27:26 UTC