- From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
- Date: Mon, 29 Apr 2002 08:44:57 -0400
- To: jos.deroo.jd@belgium.agfa.com
- Cc: jjc@hplb.hpl.hp.com, www-webont-wg@w3.org
From: jos.deroo.jd@belgium.agfa.com Subject: Re: TEST, SEM: test cases for dark triples Date: Sat, 27 Apr 2002 22:08:05 +0200 > > > [...] > > > > > That worked as such but was meaningless/misleading and is now thrown away. > > > We now have (as a matter of test) another possible pair of er > > > > > > { ?s ?p ?o . ?s a [ owl:restrictionOf ( ?p ?C ) ] } log:implies { ?o a ?C } > . > > > > > > { ?s ?p ?o . ?o a ?C } log:implies { ?s a [ owl:restrictionOf ( ?p ?C ) ] } > . > > > > Well these are a rather strange pair of inference rules. They certainly > > are not correct for any of the DAML+OIL constructs, nor for any OWL > > construct that I have seen proposed. > > > > Could you please give me an informal description of what owl:restrictionOf > > is supposed to mean? > > the ?x is shorthand "for all x elements of the domain of discourse" > ?s ?p ?o . ?s a [ owl:restrictionOf ( ?p ?C ) ] in the premise is > actually ?s ?p ?o . ?s a ?x . ?x owl:restrictionOf ( ?p ?C ) > (btw the . is shorthand for logical conjunction) > owl:restrictionOf is a rdf:Property whose > rdfs:domain is owl:Class and whose rdfs:range is owl:Seq > i.e. a sequence of a rdfs:Property followed by an owl:Class > also owl:restrictionOf is an owl:UnambiguousProperty > so we don't need a Skolem function in the second consequent > > an example could be something like > :Person rdfs:subClassOf [ owl:restrictedBy ( :hasParent :Person ) ] . > which is btw also an example of :Person circularity > > -- > Jos > This helps me not at all. I need to know what owl:restrictionOf is supposed to mean, not what arguments it takes! Trying to determine what owl:restrictionOf means from your rules leads to the following reasoning: Consider the following situation: i p o . i a [owl:restrictionOf ( p C ) ] . From this and application of the rule { ?s ?p ?o . ?s a [ owl:restrictionOf ( ?p ?C ) ] } log:implies { ?o a ?C } . produces o p C . which is the usual inference from a standard DL value restriction. However, in the following situation i p o1. o1 a C1 . the rule { ?s ?p ?o . ?o a ?C } log:implies { ?s a [ owl:restrictionOf ( ?p ?C ) ] } . produces i a [ owl:restrictionOf ( p C1 ) ] . This is definitly *not* what would follow from a standard DL value restriction. Taken together, the two rules produce truely bizzare situations. For example john sibling jake . jake a Man . john sibling jill . jill a Woman . produces, using two applications of the second rule, john a [ owl:restrictionOf ( sibling Man ) ] . john a [ owl:restrictionOf ( sibling Woman ) ] . Then, from the first rule, jake a Woman . jill a Man . This is why I am totally confused as to what you want owl:restrictionOf to mean. Peter F. Patel-Schneider Bell Labs Research.
Received on Monday, 29 April 2002 08:46:40 UTC