2. The method of claim 1 , wherein the determining comprises: building a closure of the second subset; and determining whether the closure of the second subset intersects with the first subset.
2. The method of claim 1 , wherein the determining comprises: building a closure of the second subset; and determining whether the closure of the second subset intersects with the first subset. 3. The method of claim 2 , further comprising: determining that the sub-ontology is safe if the closure of the second subset does not intersect with the first subset.