|What is worrying me is to destroy the semantic web stack, going
(1) serialisation --> triples --> semantics
The OWL2 initiative seems to change this entire stack, producing something like this (with some complicated scenario that guarantees some level of compatibility):
(2) serialisation --> triples --> semantics ^ another serialisation
[if you use a variable-pitch font: <another serialisation> points *directly* to <semantics>]
This upsets my entire toolchain, which is based on the assumption of model (1). Now, of course, some people may think this is just my problem. I believe this is not the case. If we re-introduce the immediate mapping from syntax to semantics, we are likely to fall into the same trap from which knowledge representation formats suffered for decades: different syntaxes with 90% semantic overlap that are hard to unify in a single application (I assume OWL2 is not the final KR language).
(not the complete mail, it would be too long to reproduce here, see the original mail
See also discussion thread on the list.
Subject: [LC response] To Jan Wielemaker
Thank you for your comment
on the OWL 2 Web Ontology Language last call drafts.
Unfortunately, your comment is based on our fault in not conveying the message clearly enough. The technical fact is that there is no change between OWL 1 and OWL 2 in terms of the stack you refer to in your comment.
Indeed, Section 2.1 of the Conformance and Test Cases document states the following:
"Several syntaxes have been defined for OWL 2 ontology documents, some or all of which could be used by OWL 2 tools for exchanging documents. However, conformant OWL 2 tools that take ontology documents as input(s) must accept ontology documents using the RDF/XML serialization [OWL 2 Mapping to RDF Graphs], and conformant OWL 2 tools that publish ontology documents must, if possible, be able to publish them in the RDF/XML serialization if asked to do so (e.g., via HTTP content negotiation)."
In other words, the only _required_ exchange syntax among OWL 2 tools is based on RDF and is RDF/XML (the only small caveat, referred to by the 'if possible' remark in the text, is that there are valid RDF graphs that cannot be serialized into RDF/XML, eg, if complex URI-s are used for property IDs). Ie, the situation has _not_ changed compared to OWL 1.
The confusion obviously comes from the fact that the OWL/XML syntax, which was published as a note for OWL 1, is now on Recommendation track. OWL/XML for OWL 1 was an optional feature that OWL 1 tools could implement if they wished to do so. The fact that OWL/XML is now planned as a recommendation has not changed this.
All that being said, the Working Group recognizes that this issue may lead to confusion, as witnessed by a number of comments that expressed the same concerns as yours. The group will take appropriate steps in conveying this information better by, eg, including multi-syntax formats into the structural specification and functional-style syntax document, or making the situation clearer in the appropriate status sections. Details of these steps are not yet decided at this time.
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