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Re: [ontolog-forum] Interpreting OWL

To: "'[ontolog-forum] '" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "Ian Bailey" <ian@xxxxxxxxxxxxxxxx>
Date: Sun, 17 Oct 2010 13:55:08 +0100
Message-id: <00b401cb6dfa$881f37f0$985da7d0$@com>

Hi Sean,


I would be tempted to leave OWL out of the equation altogether for EXPRESS, and use RDF/RDFS. The most used OWL representation is the RDF one, so I think this makes sense for EXPRESS too.


I think you could do a pretty good job of modelling the EXPRESS meta-model in RDF(S). It would avoid a lot of the baggage that comes with OWL (I can hear the DL nuts lighting their torches as I type) and would be using a similar approach to the RDF form of OWL. This would then make the comparison you mention a bit more straightforward.


There are a few oddball aspects in EXPRESS such as SELECTs and SUPERTYPE OF clauses that, although they’ll map, won’t turn out quite as the STEP community would expect them to.


All you need to do then is persuade the OMG to do the same thing – though there is the added complication of UML being wedded to MOF. An RDFS representation of MOF might even give us a replacement for XMI that actually works, and that can’t be a bad thing.






From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of sean barker
Sent: 17 October 2010 12:17
To: ontolog-forum@xxxxxxxxxxxxxxxx
Subject: [ontolog-forum] Interpreting OWL



Apologies for asking another question before I have finished responding to the last, but a question arose at the last STEP meeting which has some tricky implications.


The statement was made that anything that could be written in EXPRESS could be written in OWL. However, some of the constructs in EXPRESS, particularly those concerning the cardinality and structure of relationships are not directly obviously expressible in OWL, such as the distinction between a bag and a set. However, it should be possible to create a first order interpretation of OWL such that an EXPRESS relationship is a subtype of 'thing', and the relationship constraints are then OWL properties. EXPRESS Entity and Type also become subtypes of 'thing'


This then allows one to construct a second order interpretation by suptyping Entity, Relationship and Type as STEP generic entities, such as Product, Version, View, Property, Property-Representation, Representation-Presentation etc. That is, EXPRESS entities provide an upper level ontology for STEP in OWL.


One can then create a third order interpretation, as is done in the STEP Application Protocols, in which the STEP generic entities are interpreted in the context of a business process, so that Product is either a product (AP 203) a part (AP 214) or a technical data package (AP 232).


Two questions arise. Firstly, one could also describe other modelling languages such as UML and IDEF1X as first order interpretations of OWL (in the sense above) (and even of OWL itself). Could one then compare the expressive power of such formalisation by creating a lattice of modelling languages? (This would also expose ambiguities in the languages).


Secondly, would the second and third order interpretations be compatible with anybody else's use of OWL? For example, whether a particular (EXPRESS) property is a property of a product is contingent on the Version (an implied temporal commitment) and the View.

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