- From: Gerd Wagner <wagnerg@tu-cottbus.de>
- Date: Wed, 17 Jan 2007 11:28:00 +0100
- To: "'Alan Ruttenberg'" <alanruttenberg@gmail.com>, "'Holger Knublauch'" <holger@topquadrant.com>
- Cc: <public-owl-dev@w3.org>
> 3) A certain skirting around the issue of how RDF and OWL semantics > differ from the usual database view of the world. Domain and Range > are a constant source of confusion. Open world assumptions also > makes, e.g. cardinality restrictions, not behave the way one would > expect them to. I think the choice of open world assumption is well > motivated, Is it really (in all cases)? I don't think that there was ever any deliberate design decision in favor of the "open world assumption" (OWA) versus the CWA in the making of OWL. The OWA is just in the baggage of classical mathematical logic, so if you stick to that formalism, you get it for free (without having any chance to reject or weaken it). > but we do need some ability to do closed-world reasoning > such as constraint checking, and from a messaging point of view a > more head-on approach to discussing how and why both OWL and RDF > differ from databases. Database languages, such as SQL, are based on computational experience and best practices. Their formalizations in computational logics do not imply the OWA. In fact, they seem to suggest a controlled co-existence of both the CWA and the OWA. In order to help RDF and OWL to be more compatible with computational best practices (such as the distinction between facts, rules and constraints), it may be necessary to abandon/relax its strict classcial logic semantics. -Gerd --------------------------------------------- Gerd Wagner http://oxygen.informatik.tu-cottbus.de/IT
Received on Wednesday, 17 January 2007 10:28:10 UTC