>>just a small datapoint to what you say. Although I essentially agree, we >>should not forget that even OWL-Lite requires a Description Logic >>reasoning engine (if one wants to use reasoning, that is). > >I also think we should consider a recommended practice of using OWL Lite or >DL where possible (i.e., when the knowledge base can be expressed in no >more >than DL). > >With regard to the point "if one wants to use reasoning", unfortunately, >those who are only interested in querying must be aware of reasoning. For >example, the property "sameAs" is symmetric. Thus, if your knowledge base >has "A sameAs B", one would fully expect the query "?x sameAs A" to return >"B". However, query engines without reasoners won't. Therefore, one must >put >"A sameAs B" and "B sameAs A" into their knowledge base in order to get the >expected results. >
Entering "A sameAs B" and "B sameAs A" into the knowledge base (to get the expected results) just means that you are performing forward-chaining rather than backwards-chaining. For smaller knowledge-bases expected to handle a large number of queries, forward-chaining makes sense. My point is that pre-computing a result doesn't allow you to avoid reasoning. You're just making a trade-off between space and time. (Note that once you introduce certain constructs forward-chaining may not be possible because of an undefined fixpoint.) Peter