- From: Solbrig, Harold R. <Solbrig.Harold@mayo.edu>
- Date: Fri, 23 Jan 2009 16:46:01 -0600
- To: "Bijan Parsia" <bparsia@cs.manchester.ac.uk>, "W3C OWL Working Group" <public-owl-wg@w3.org>
The mention of "superseding" and "superseded" begins to sound like incremental versions. Might one want more than just a list of what is "hidden" and what is "active"? I would think that much of the value of the non-active axioms would include, at bare minimum, the relative order in which new axioms were introduced and "hidden" axioms were deactivated. It would be possible to introduce new axioms via the notion of additive "micro-versions" - incomplete collections of axioms that, when combined with a previously complete ontology, creates a new version of the same. This still presents the same fundamental problem - how to indicate that an axiom should no longer have logical force - but it would allow the relative order of changes to be encapsulated in the information associated with the "micro-version" itself, something that is available already. Let me mention related requirement that we have encountered. We have a need to be able to classify an ontology and subsequently transmit both the asserted and the logical inferences for display and consumption in secondary resources such as wikis and other tools. As these tools may create additional axioms, we need to differentiate the asserted from the inferred - both as important information to the editors and to be able to remove or ignore these axioms when the modified ontology is subsequently re-classified. While this is a slightly different use case, it still involves the same notion - some sort of tag or property on an axiom that affects the way that it is interpreted. Harold Solbrig | Division of Biomedical Statistics and Informatics | 507-293-3774 | solbrig.harold@mayo.edu -----Original Message----- From: public-owl-wg-request@w3.org [mailto:public-owl-wg-request@w3.org] On Behalf Of Bijan Parsia Sent: Friday, January 23, 2009 3:33 PM To: W3C OWL Working Group Subject: LC Comment: "Hidden" Axioms This is the result of discussions with people at Manchester working on a collaboration with Siemens Medical Health Services (i.e., an industrial project). We would like the ability to "turn off" the logical force of axioms without having to remove them from the structural model. Currently, the only way to directly hide an axiom from a reasoner in an OWL document is to use one of the commenting capabilities of the serializations (e.g., <!-- -->). However, this isn't really workable for a number of reasons including that such comments tend to not survive conversion, or even parsing (since it has no place in the structural model) and such comments are difficult to retrieve or manipulate. One basic use of this is to maintain superseded (or potentially superseded) axioms in the same ontology as the superseding ontology. In a sense, this is like deprecatedClass except that it has a clear operational meaning (whereas deprecatedClass was unspecified). From an API point of view, hiding an axiom (rather than deleting it) is a natural way of exploring the consequences of changes. It's nice to be able to persist such experiments in the canonical format. Ideally, in our view, this would be effected by a designated "annotation". I've gotten some feedback that this would be an exception to the "annotations don't affect the meaning". True. But I don't think it's a harmful exception *if built in*. For obvious reasons it *can't* be conformingly implemented as an extension to OWL 2 since all user defined annotations can be deleted without changing the logical meaning of the ontology. Keeping it as an annotation (rather than a distinct syntactic flag) is both easier to spec (since it doesn't change as many documents) and can be combined with axiom names to produce multiple external "profiles" of an ontology (e.g., by hiding different sets of axioms from different external files which import the core ontology). This makes it easier to make cut down versions of an ontology from the same source. I apologize for not raising it earlier. I had been thinking that it could all be handled at a higher level. But in order to publish ontologies with hidden (in this sense) axioms, it has to be part of the core spec. Otherwise, conforming tools will misinterpret such ontologies. Cheers, Bijan.
Received on Friday, 23 January 2009 22:46:39 UTC