If o2 owl:imports o1, o2 is tightly bound to o1. If I want to develop another ontology say, o3, and want to use the concepts of o2, I must also have to import the o1 as well.
I would think an ontology author would only import a second ontology if the terms / concepts within *depended* on terms / concepts in the second ontology, in which case it would follow that a third ontology (or an instance graph) that wanted to use o2 be required to import o1. By depend, I mean for purposes of reasoning.
First, such kind of chain dependency will eventually leads to a big-monolithic ontology.
Only if the linking mechanism is done arbitrarily and without forethought with regard to recursive dependencies. If the fragments are grouped atomically and distributed with links where the dependencies are neccessary, the 'trail' from the original ontology to all the included ontologies (the resulting closure) would be exactly the neccessary content to do reasoning with the terms used.
This of course, places a quite a burden on the ontology author to partition and link the ontologies with care, but I think this shifts the burden in the right direction.
Second, it hurts the sharing capability of o2. What if I only want to import o2 but not necessarily agree to o1?
If the linking is only used where the dependency is *neccessary* then the import is (essentially) transparent and irrelevant to a third ontology (or instance graph) that wishes to use terms from o2.
I must either pay the price, i.e, to be forced into using o1. Or impossible because I might have some assertions in o3 that might incur inconsistency with o1 but not necessarily o2.
Once again, if o1 is imported from o2 because it relies on the terms in o2, there wouldn't be any inconsistencies, and if there are it is more likely due to improper fragmentation / linking by the author than a unintended / unexpected use of the ontology terms.
Chimezie Ogbuji Lead Systems Analyst Thoracic and Cardiovascular Surgery Cleveland Clinic Foundation 9500 Euclid Avenue/ W26 Cleveland, Ohio 44195 Office: (216)444-8593 [EMAIL PROTECTED]
