- From: Pat Hayes <phayes@ihmc.us>
- Date: Sat, 5 Jan 2008 19:34:58 -0800
- To: "Michael Schneider" <schneid@fzi.de>
- Cc: "Evren Sirin" <evren@clarkparsia.com>, "Owl Dev" <public-owl-dev@w3.org>
> >> On 11/2/07 3:23 PM, Michael Schneider wrote: >>> Hi, Evren! >>> >>> Evren Sirin wrote on November 02, 2007: >>> >>> >>>> Michael, >>>> You are correct in your understanding of punning. It is true that >>>> punning semantics is strictly weaker than OWL-Full semantics and the >>>> inferences you will get will be a subset of OWL Full entailments. > >Is this a certain fact? I remember to have heard this claim a few times >before now, but don't remember to have ever heard about evidence for it. >Since there is no 1.1-Full draft at the moment, is there some proof that >this would be true for 1.0-DL+Punning in comparison to 1.0-Full? Yes, because in the Full semantics, :sameAs entails :equivalentClass, but not in the punning semantics. It is easy to construct many examples based on this which illustrate the disconnect between punning and the RDF/hilog style semantics. One way to minimize (although not completely eliminate) these issues would be to redefine what 'sameAs' means in 1.1. 1.0:sameAs really does mean equality. In 1.1, however, it no longer means that, as it is restricted to individuals. If this were altered so that 1.1:sameAs means equality for all the name categories, i.e. if it was the conjunction of DL-sameAs, equivalentClass and equivalentProperty, then most entailments would carry over from the 1.0 case to the 1.1 case. This would require introducing a new 'weak' identity for individuals, call this sameThingAs (just for now), then sameAs means the same thing in 1.0-Full and 1.1-Full, and 1.0-DL:sameAs means the same as 1.1-DL:sameThingAs; but since 1.1:sameAs when restricted to individuals means 1.1:sameThingAs, and since 1.0 only allows sameAs to be used between individuals, all 1.0 DL ontologies should retain their meanings in 1.1-DL also. The only case that would need care when moving from 1.0 to 1.1 is taking an existing 1.0-DL ontology and extending it using punning to be 1.1-DL legal but not 1.0-DL-legal. In this case, the 1.0-sameAs statements need to be restricted (I presume: Im not an expert on the logistics of punning) to the individual case, which in this suggested scenario would require changing the ontology by replacing sameAs by sameThingAs. This might be considered a dealbreaker, but I think the idea is worth careful consideration, as it is semantically more correct and makes the overall DL/Full relationship in 1.1 much less confusing. (And how many published OWL ontologies actually use sameAs in ways that are remotely likely to be confused by subsequent punning extensions?) Anyway, though I would put this on the table for discussion. Pat -- --------------------------------------------------------------------- IHMC (850)434 8903 or (650)494 3973 home 40 South Alcaniz St. (850)202 4416 office Pensacola (850)202 4440 fax FL 32502 (850)291 0667 cell phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
Received on Sunday, 6 January 2008 03:35:14 UTC