Dear Hilmar,
Thanks for your questions about DSW. Steve will have more to add, but the simple answer is that DSW was not indented to say anything new about the existing DwC classes themselves, other than offering a suggestion, based on Steve's extensive search for community consensus on usage in the tdwg-content list, of how the classes best relate to one another. These relations are indicated by the coining of a set of predicates that offer more semantic content than the generic dwc:relatedResourceID, and permit more succinct SPARQL searches, as Bob pointed out.
Based on Steve's review, the range of ways of using the dwc:Occurrence class has been wide, and we suggested a restricted usage in this ontology: the documented presence of an individual organism at a particular event (= space x time); a specimen/photo/observation is in this case not the occurrence itself, but provides evidence for the occurrence.
This all depends on the one new class in DSW, the IndividualOrganism, which Steve and others have been proposing as a fundamental class for modeling biodiversity data. With an IndividualOrganism class, we can easily link from the knowledge domain of biological specimens to that of population biology, where observed/remeasured individuals are the core unit.
We developed DSW to serve our pragmatic need for a semantic template with which to serve data as RDF. Reasoning with it is possible, as you and Bob noted, but I agree, the range of discoveries is limited, because of the few logical restrictions currently in DSW. Perhaps we should not have used the word `ontology' to describe it?
As is still the case now as when Steve announced DSW to tdwg-content, we consider DSW primarily a suggestion for further discussion, and hopefully for further community development (i.e. via the nascent TDWG RDF/OWL Task Group). It `makes sense' to us, and we're using it to model data, but would appreciate significant comment and criticism, including the need to add more logical restrictions.
Best,
Cam
[ There's more on our rationale behind DSW at: http://code.google.com/p/darwin-sw/wiki/Rationale ]
On Wed, 25 Jan 2012, Hilmar Lapp wrote:
Hi Steve and Cam,
I have a question re: your design of the current Semantic Darwin Core ontology. (And this is assuming that with the published 0.2 version I have the latest one in hand.)
My understanding is that all classes in DSW are imported from either DwC or DC (or FOAF), in order to reuse those terms. While that's a good idea in principle, it seems that DSW is actually not saying much new (in a semantic sense) about them, except to declare them to be OWL classes, and to assert them as disjoint from each other (or equivalent in one case). DSW then adds a variety of object (and some data) properties, which distinguish themselves from those in DwC by declaring domain and range axioms for them. But that doesn't say anything about the classes either, nor does it, I would argue, about the properties - domain and range constraint really only say something about the instances for which one asserts those properties.
So by itself the DSW won't allow me to infer anything about the classes and properties in the ontology (aside from disjointness), though it will allow me to make more inferences about instance data to which it is applied than DwC would. And those additional inferences would consist only of the instances' class memberships (and their non-memberships).
I'm wondering a) whether I'm missing something here and am in error, and if not, b) whether the above was indeed the extent of what you wanted to achieve with DSW. Either way, what are your current plans with the ontology? It doesn't seem to have changed for a while.
(And please forgive me if this isn't the right list to post to - I couldn't find a DSW-specific one on the Google code homepage.)
Cheers,
-hilmar
=========================================================== : Hilmar Lapp -:- Durham, NC -:- informatics.nescent.org : ===========================================================