I sent this to tdwg-tag instead of this more appropriate list. My apologies to those who see it twice, along with any replies to it.
Jonathan Reese, an employee of the Science Commons and TDWG member (and who knows way more about semantic web than I do) recently sent me this. I copy it here with his permission. Each of the paragraphs seems to me to be germane in different ways to the discussions about what should be an Individual. For those not deep into RDF, for the word "axiom", you could loosely understand "rule", although that term also has technical meaning that is sometimes a little different. Jonathan raises an important use case in the second paragraph, which is data quality control. That's a topic of interest to many, but especially those following the new Annotation Interest Group. Originally, this was part of a discussion we had about my favorite hobby horse, rdfs:domain. He is not on my side. When people who know more than I do about something are skeptical of my arguments about it, I usually suspend disbelief and temporarily adopt their position.
Jonathan's first point is pretty much what Paul Murray observed yesterday in response to a question of Kevin Richards.
"(a) subclassing is the way in RDFS or OWL you would connect the more specific to the less specific, so that you can apply general theorems to a more specific entity. That is, a well-documented data set would be rendered using classes and properties that were very specific so as to not lose information, and then could be merged with a badly-documented data set by relaxing to more general classes and properties using subclass and subproperty knowledge.
(b) axioms (i.e. specificity) are valuable not only for expressing operational and inferential semantics, but also for "sanity checking" e.g. consistency, satisfiability, Clark/Parsia integrity checks ( http://clarkparsia.com/pellet/icv/ ), and similar. Being able to detect ill-formed inputs is incredibly valuable.
People talk past one another because there are many distinct use cases for RDF and assumptions are rarely surfaced. For L(O)D, you're interested in making lots of links with little effort. Semantics is the enemy because it drives up costs. For semantic web, on the other hand, you're interested in semantics, i.e. understanding and documenting the import of what's asserted and making a best effort to only assert things that are true, even in the presence of open world assumption and data set extensibility. Semantics is expensive because it requires real thought and often a lot of reverse engineering. People coming from these two places will never be able to get along." ---Jonathan Rees in email to Bob Morris ================
Bob Morris
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