- From: naudts guido <naudts_vannoten@yahoo.com>
- Date: Sun, 21 Mar 2004 03:59:27 -0800 (PST)
- To: cwm <public-cwm-talk@w3.org>
Hallo, When inferencing there are three moments at which inconsistencies can be detected: 1) before inferencing 2) during inferencing 3) after inferencing. Before inferencing we have a set of formulae. Take the triples: (1) :x owl:oneOf (:a :b :c). :d a :x. This is a clear inconsistency and should be detected of course. However: (2) :c a owl:restriction; owl:onProperty :p; owl:minCardinality "3"^^xsd:integer. However before inferencing no member of the class exists. But members of the class might be discovered during inferencing. Consider the situation after inferencing: there is a set of formulae, a set of substitutions to the query and a proof of the result. Applying the susbtitutions to the set of formulae together with the proof gives a new set of formulae (the proof is a formula too). The found solution is valid when this new set of formulae is a consistent set; the solution is not valid when this set is not consistent. Thus it follows that the detection of inconsistencies needs only to be done after inferencing, thereby eliminating invalid answers. Of course, inconsistencies like (1) could be detected before or during inferencing (but need not to) in order to enhance the efficiency of the inference process. Conclusion: inconsistencies that are irreparable(i.e. they cannot go away by the inferencing process) should be detected as soon as possible; inconsistencies that can change should only be detected after the inferencing process: these include certainly restrictions with: owl:someValuesFrom; owl:cardinality; owl:minCardinality; owl:maxCardinality. Checking consistencies at the end of inferencing should even allow to introduce "assert" and "retract" primitives i.e. adding or deleting triples from the formulae during inferencing.In that case, however, all inconsistency handling needs to be done after inferencing. __________________________________ Do you Yahoo!? Yahoo! Finance Tax Center - File online. File on time. http://taxes.yahoo.com/filing.html
Received on Sunday, 21 March 2004 06:59:59 UTC