From: pat hayes (phayes@ai.uwf.edu)
Date: 04/24/01
Checking thru the walk-thru. The section which introduces properties is worded in a way that suggests a different semantics from the one given in the model theory. The example says that the domain of hasParent is #Animal, and this clearly suggests that the intention is that this should mean that every animal has a parent, ie that hasParent applies to the entire domain class (in contrast to the range specification.) I wrote the following 'explanation' before realising that it might not be true: "The range specification restricts the property from 'above', ie it specifies a class into which the value of the property must fit, while the domain restricts it from 'below', ie it specifies a class which must be included in the class of things that the property can be applied to. " Is this correct?? Because if so, the semantics is wrong at this point. It says <rdfs:domain,?P,?C> means: if <x,y> in IR(?P) then x in IC(?C) but if the above is correct then it ought to say: <rdfs:domain,?P,?C> means: if x in IC(?C) then for some y, <x,y> in IR(?P) If the semantics is correct, however, then the example in the walkthrough is rather misleading, and we will need to correct against any potential misunderstanding. Also, in this case, HOW does someone give a 'lower' bound to the domain of a property? Eg how can one say that hasParent applies to *any* animal? (If both domain and range restrict from above, then it would be consistent to give all properties empty domains and ranges.) I await clarification from the Semantic Gurus, and will write appropriate prose for the walkthru when clarity is restored to my mind. Pat Hayes PS. A related question. If <rdfs:domain,?P,?D> <rdfs:range,?P,?R> <inverseOf,?P,?S> does it follow that <rdfs:domain, ?S,?R> <rdfs:range,?S,?D> ?? PPS. The only way to really learn something is to try teaching it to other people :-) --------------------------------------------------------------------- IHMC (850)434 8903 home 40 South Alcaniz St. (850)202 4416 office Pensacola, FL 32501 (850)202 4440 fax phayes@ai.uwf.edu http://www.coginst.uwf.edu/~phayes
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