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I'd suggest that perhaps the confusion arises because "This instance is (not) 'valid' according to that ontology." might be inferred from an instance and an ontology (under certain conditions), and that's the soul of what we're asking when we define constraints on the data. Perhaps OWL can be used to express conditions of validity, as long as we represent the quality "valid" for use in inferences.

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A. Soroka
The University of Virginia Library

On Sep 13, 2013, at 11:00 PM, CODE4LIB automatic digest system wrote:

> Also, remember that OWL does NOT constrain your data, it constrains only the inferences that you can make about your data. OWL operates at the ontology level, not the data level. (The OWL 2 documentation makes this more clear, in my reading of it. I agree that the example you cite sure looks like a constraint on the data... it's very confusing.)

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