There is an interesting article here:

http://www.cs.vu.nl/~guus/public/owl-restrictions/

That discusses the differences between OWL and UML.

One of the features of OWL that I like is the notion of a necessary and sufficient properties but alas this is lacking in UML. Sufficient conditions allow you to determine if an instance is a member of a class when it in not explicitly stated. You can therefore receive and object and work out what it is according to an ontology of your choice - which seems pretty useful to me. It is a mechanism, I believed, could enable us to integrate a simple core ontology with more complex specialist ontologies that some network participants may choose to use. It is not available in UML but could be used to reason about a UML ontology expressed in OWL or RDFS.

OWL doesn't do qualified cardinality restrictions as well as UML - but there are work rounds and proposals and I am not sure how important this is.

There is also a good quote in the article on data modeling versus building ontologies:

"A data model is a model of the information in some restricted well-delimited application domain, whereas an ontology is intended to provide a set of shared concepts for multiple users and applications. To put it simply: data models live in a relatively small closed world; ontologies are meant for an open, distributed world (hence their importance for the Web)."

I think we are sometime confusing the two in our discussions.

Bottom line is:

You can't express everything in UML or OWL.
If we want to assure that we can swap between two or more modeling languages then we can't use all the feature of any of them but have to come up with a subset.

The answer never includes a single TLA. <- apart from this answer!

My personal feeling is that anything that is defined centrally by TDWG should use the lowest common denominator of features anyhow.

As usual I am grateful for you comments/thoughts.

Roger

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 Roger Hyam
 Technical Architect
 Taxonomic Databases Working Group
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 http://www.tdwg.org
 roger@tdwg.org
 +44 1578 722782
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