17. The apparatus of claim 16 , further comprising: means for determining that the sub-ontology is safe if the closure of the second subset does not intersect with the first subset.
17. The apparatus of claim 16 , further comprising: means for determining that the sub-ontology is safe if the closure of the second subset does not intersect with the first subset. 18. The apparatus of claim 17 , further comprising: means for storing the sub-ontology.