- From: Jos De_Roo <jos.deroo.jd@belgium.agfa.com>
- Date: Fri, 17 May 2002 10:35:38 +0200
- To: pfps@research.bell-labs.com
- Cc: "hendler" <hendler@cs.umd.edu>, "www-webont-wg" <www-webont-wg@w3.org>
[...] > Well, suppose WebOnt fixed the layering issue, perhaps by using an approach > with explicit comprehension principles that did not have paradoxes. > (Remember, however, that there are several people who believe that this is > probably not possible, and there is no proponent for this approach.) It > still would be possible to have a too-weak solution. For example, Jos has > been producing log:implies stuff that are, in a sense, like the > comprehension principles. As far as I can remember, every set of > implications that he has produced has been shown to be too weak, in the > sense that there are desirable consequences that do not follow from the > rules. 1) there is one thing I would like to reiterate suppose we have a paradoxical pair such as e.g. { ?x a :R } log:implies { ?x a [ owl:complementOf ?x ] } . { ?x a [ owl:complementOf ?x ] } log:implies { ?x a :R } . then deriving a contradiction from that is indeed a VALID inference but it is not a SOUND inference and I think we should aim for sound reasoners giving sound arguments (an argument is sound if and only if it is valid and all its premises are true). 2) yes, more desirable consequences should follow from more implications, but also there should be more rules for deriving inconsistencies such as e.g. { :rule16r1 . ?s ?p ?o . ?s a [ a owl:Restriction; owl:onProperty ?p; owl:minCardinality ?min; owl:maxCardinality ?max; owl:toClass ?C ] . { ?s ?p ?o . ?o a ?C } math:entailCount ?n . ?n math:lessThan ?min } log:implies { ?s :inconsistentWith owl:Restriction } . where math:entailCount is just something to count how many times we can entail its subject graph from what was given -- Jos
Received on Friday, 17 May 2002 04:44:58 UTC