To: | "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>, public-owl-dev <public-owl-dev@xxxxxx> |
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From: | Bene Rodriguez-Castro <beroca@xxxxxxxxx> |
Date: | Thu, 29 Apr 2010 20:02:10 +0100 |
Message-id: | <i2jea8cd28f1004291202s57fd1991ufff31ac94faa0460@xxxxxxxxxxxxxx> |
Hi Doug, I found very useful reference [3] from your first reply ( Instances of Instances Modeled via Higher-Order Classes ). I realized I tend to tangle the concept of instance/individual and class/meta-class but the definitions in the paper together with the ontology of levels of meta-classes definitely help to clarify these concepts. (Reference [4] in the same email does not seem to be publicly available yet). Some comments in-line below and some requests for clarification if possible. Thanks, Bene On Sun, Apr 25, 2010 at 6:08 AM, doug foxvog <doug@xxxxxxxxxx> wrote:
In this example :Red, :Rose and :White are subclasses of :WineColor. This is modelled following Pattern 2 (variant 2) in the cited W3C note: http://www.w3.org/TR/swbp-specified-values/.
The relationship between :Value_Partition and :WineColor is an interesting point. It seems to me now, after the comments in this thread, that the representation of :Value_Partition as a class is controversial for the same reasons that classes such as :WineByGrape, :WineByColor and in general XbyY are. They seem to provide "meta-knowledge". Knowledge about other classes in the ontology and that cannot be represented as a "class" using OWL DL set-based semantics.
And although the Normalization mechanism suggests to include the notion of value partition (or refiner) as a class in the inheritance structure of the ontology, I realized Alan Rector already referred to this controversy in the cited paper. (Section "Issues and Problems" in "Modularisation of domain ontologies Implemented indescription logics and related formalisms including OWL").
I agree with this but then I guess I am misinterpreting something regarding the OWL DL semantics or the elements that participate in the binary relationship of the partition.
Going back to the W3C note: http://www.w3.org/TR/swbp-specified-values/. It defines two patterns to represent a partition that can be expressed in OWL DL.
I would interpret the partition in Pattern 1 as a binary relationship between a class :Health_Value and a set of mutually disjoint *individuals* that cover the class {:poor_health, :medium_health, good_health}.
I would interpret the partition in Pattern 2 (both variant 1 and 2) as a binary relationship between a class :Health_Value and a set of mutually disjoint *subclasses* that cover the parent class {:Good_health_value, :Medium_health_value, :Poor_health_value}.
The definition of partition that you give (which *cannot* be expressed in OWL-DL) "seems to align" to the definition in Pattern 2 (which *can* be expressed in OWL DL). That's why I think I must be misunderstanding something.
I'm afraid I'm not sure which classes from the :Wine example fit into that description.
Yes, I can see this now.
Agreed.
Yes.
I'm afraid I'm not sure what the generic terms "pattern", "rule", "meta-type" refer to in this case or how to interpret the statements in the paragraph in terms of OWL. It would be very helpful if you could you point out a specific example to help illustrate what it is being referred to by "meta-type", "pattern of rule", "multiple rules of the same pattern", "the definition of the rule patterns"...
I don't think they are *identical* thou. These are the intended definitions. There is one difference:
The class :MerlotWine is *equivalent* to the class defined by the someValue restriction on the the property :madeFromGrape. The class :SpecificMerlotWineClass is a *subclass* of the class defined by the same restriction of the same property.
This representation allows a reasoner to infer that :SpecificMerlotWineClass is a subclass of :MerlotWine. This sort of "pattern" is one of the keys in the Normalization mechanism in order to enable a reasoner to infer all multiple inheritance relations among the classes involved in an ontology model.
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