Raw

There's been recent activity in the OWL community aiming towards extensions which provide OWL DL with increased expressivity. (There's also work ongoing around subsets of OWL that are closer to RDF, but that's a different story - check these posts from Jim Hendler and Ora Lassila).

The main proposals are captured in the OWL 1.1 specification, although it should be noted that this as yet has no official standing, and "1.1" is just a working title. There are several significant additions, and the primary specification is done in an different fashion than OWL (with a new Functional-Style Syntax).

Personally I'm skeptical this is the right time for any major overhaul of OWL (like, don't break the build before a demo...). Whatever, there's no doubt there will be changes one day. There are syntax-related issues with 1.1, but as Bill deHora put it (in a different context): "If there's a Maslow hierarchy of needs for the Web, syntax is on the bottom.". As far as I'm concerned the big question is whether (maximal) logical compatibility is maintained with the existing layers of the Semantic Web stack, i.e. RDF and OWL.

Do what you like, just don't hurt the triples.

Some sentences, especially in earlier drafts of 1.1, seemed to suggest the distance from RDF was such that interoperability would be a non-starter. (It's worth bearing in mind that the requirements of the OWL/Description Logics community don't necessarily coincide with those of the (Semantic) Web community at large). I've barely started getting my head around the new material, it will be a good while before I'll have any hope of judging this for myself. I really am not a logician.

Ian Horrocks, who is, just posted the following to the public-owl-dev@w3.org list:

The current status is that OWL 1.1 has a triple syntax that is fully backwards compatible with OWL: any OWL DL ontology is an OWL 1.1 ontology. There are a couple of new features of OWL 1.1 that we were having trouble figuring out how to serialise as triples, but after discussions at ISWC and the OWLED workshop (thanks to Alan Ruttenberg for some helpful suggestions) we now have a solution, and a revision of the triple syntax that covers all of OWL 1.1 will soon be available. Regarding the semantics, it may not be possible to extend OWL's RDF-Compatible Model-Theoretic Semantics so as to *completely* capture the meaning of OWL 1.1 while at the same time giving *all* the triples their basic RDF meaning as facts. Due to the backwards compatibility of the syntax, however, the meaning of the OWL part of OWL 1.1 will be captured by the existing RDF-Compatible Semantics, and interest has been expressed in trying to extend this (the existing RDF-Compatible Semantics) so as to capture at least some of the meaning of the OWL 1.1 extensions.

(I'm still not 100% clear - I take that as saying not every OWL 1.1 ontology/conclusion is a valid OWL Full ontology/conclusion just yet, but it's getting closer...)

It seems almost self-evident that when major changes to existing specifications and/or entirely new Web specifications are proposed, the onus should be on the proposers to clearly demonstrate they won't break the Web ( else: " A riot is an ungly thing... undt, I tink, that it is chust about time ve had vun."). In this particular case, the work mentioned above sounds like it goes a long way to fulfilling that criterion. Looks to me like cause for (cautious) optimism.

See also: recent posts (and comments ;-) at Tales of a Semantic Web Consultancy; plus From SHIQ and RDF to OWL: The Making of a Web Ontology Language (pdf); The even more irresistible SROIQ (pdf).