Thanks Joel and Bob for the helpful examples and references. They have helped me understand this better.
By the way, I'm sorry if in my last post I sounded ungrateful for Bob's feedback on darwin-sw. Cam and I are actually quite keen to have comments and criticism about it. I just didn't want the discussion about the DwC term proposals to get sidetracked.
Steve
joel sachs wrote:
Steve,
Notice in Bob's examples that use cases are a tool for all software engineering tasks, whereas competency questions are used primarily in ontology design. A couple of advantages in expressing ontology use cases as competency questions are:
i. "Can the competency question be answered?" can be easier to answer than "Is the use case satisfied?"
ii. Posing the competency questions as queries can give hints about the structure of our desired ontology. This is somewhat ass-backwards, since the structure of the ontology determines the structure of the query (not vice versa), but since ontologies exist to be queried, thinking about the shape of queries can be helpful in determining the shape of the ontology.
To take an example:
Your Individual/BiologicalEntity use case 1 is "allow for linking multiple Occurrence records that involved the same organism at different times and/or places"
This can translate to
"Find all occurrences of [individual]"
or
select ?occurrence where { ?occurrence rdf:type dwc:occurrence . ?occurrence dwc:ofIndividual [individual] . }
We can then consider our design issues with reference to the query. For example: When answering this query, does it matter whether the scope of Individual/Biological Entity includes organelles or wolf packs? Does it matter if the Individual/BiologicalEntities are taxonomically homogeneous? To me, the clear answer to both questions is no.
Now consider your Individual/BiologicalEntity use case 3: "To link multiple Identifications of the same individual organism, particularly when these Identifications were based on different pieces of evidence arising from the same individual"
This would, I think, give rise to a number of competency questions, including: "Find all identifications of [Individual]"
or
select ?identification where { ?identification rdf:type dwc:Identification . ?identification dwc:ofIndividual [individual] . }
Now let's consider those same design issues: Does it matter if the scope of Individual includes organelles or wolf packs? No. Does it matter whether or not Individuals are taxonomically homogeneous? Yes, for the reasons you gave, which involve the non-heritability of properties in a partonomy.
Reading the above, you might think "I've gained no new insight from the competency questions." But you've already put considerable thought into how various ontology design decisions will affect our ability to satisfy the use cases. In general, the competency question methodology is meant to focus and streamline our consideration of design questions.
Joel.
On Tue, 26 Jul 2011, Bob Morris wrote:
As to competency questions, this might help more than a definition, since there is no agreed upon one: http://marinemetadata.org/references/competencyquestionsoverview Maybe there is something better since this was written.
As to use cases, http://en.wikipedia.org/wiki/Use_case is fair enough, but probably more than you want to know.
http://www.cragsystems.co.uk/SFRWUC/ is a pretty good tutorial for use case modeling with UML, and in about 4-5 clicks will get you to both definition and examples. You probably don't need to go further than that, especially because the further in you get, the more nit-picky is this particular tutorial.
On Tue, Jul 26, 2011 at 10:21 PM, Steve Baskauf steve.baskauf@vanderbilt.edu wrote:
For the benefit of the uninitiated (that would be me and possibly others), could someone please post definitions of "competency question" and "use case" along with a couple of examples of each?
Steve
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