- From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
- Date: Tue, 23 Apr 2002 13:12:08 +0100
- To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
- Cc: <connolly@w3.org>, <jonathan@openhealth.org>, <www-webont-wg@w3.org>
I think we are identifying a point of difference. The DAML+OIL model theory, (unlike the axiomatic semantics), is based on the triples *in the graph*, the syntax. The approach I was illustrating thought about the triples as *in the model* (even if not explicitly in the graph). (Which is what the DAML+OIL axiomatic semantics seems to suggest). In particular, the interesting consequences may follow if (a) I have not made a mistake and (b) we take the semantics to be constraints within the model theoretic interpretation rather than a direct mapping from the syntax. Jeremy > -----Original Message----- > From: Peter F. Patel-Schneider [mailto:pfps@research.bell-labs.com] > Sent: 23 April 2002 11:32 > To: jjc@hplb.hpl.hp.com > Cc: connolly@w3.org; jonathan@openhealth.org; www-webont-wg@w3.org > Subject: RE: SEM: circular primitive > > > I have annotated Jeremy's example. > > > J: So, here is my attempt to capture the semantics of child > J: in DAML+OIL (as I read it). > J: Frankly, I have no idea whether this is intended to be > J: permissable under the current D+O spec. If it is then > J: it seems a ludicrously cryptic way of saying it. But perhaps > J: the constraint is complicated. > J: > J: Note I use classes as instances here. > J: > J: Note I think the following is sufficiently disgusting that > J: I would be quite happy to have it as illegal; but I don't > J: think Jonathan will be able to describe the notion > J: of inherited disease without something like it. (He can of > J: course describe individual inherited diseases quite well > J: enough). > > J: # Let's not use child but parent. > J: # parent has the advantage that in general > J: # it's mincardinality is 1 not 0. > > J: parent daml:inverseOf child . > > J: InheritableClass rdfs:subClassOf daml:Class . > > J: parent rdfs:domain _:ParentDomain . > > _:ParentDomain is a class whose instances can have parents. > Let's consider one such instance, _:John > > _:John rdf:type _:ParentDomain . > > J: _:ParentDomain rdfs:subClassOf _:WithInheritableClass . > > Now _:John is an instance of _:WithInheritableClass > > J: _:WithInheritableClass rdf:type daml:Restriction . > J: _:WithInheritableClass daml:onProperty rdf:type . > J: _:WithInheritableClass daml:hasClass InheritableClass . > > _:WithInheritableClass is a restriction, and consists of those individuals > whose types contain an instance of InheritableClass. > > In particular, _:John has a type that is an InheritableClass, lets call > this type _:JohnsInheritableType > > J: InheritableClass rdfs:subClassOf daml:Restriction . > > As _:JohnsInheritableType is an InheritableClass it also is a daml:Restriction > > J: InheritableClass rdfs:subClassOf _:par . > J: _:par rdf:type daml:Restriction . > J: _:par daml:onProperty daml:onProperty . > J: _:par daml:hasValue parent . > > Now _:par is the class that consists of objects that have a daml:onProperty > relationship to parent. However, this is *all* that it is, for *two* > reasons. First, this is not sufficient to make a full DAML+OIL > restriction. Second, even if is was, this would not be in the RDF *graph*, > and the RDF graph is all that counts in the DAML+OIL model theory. > > J: # Saying the same in English is > J: # Within the class InheritableClass the > J: # property daml:onProperty has a local constraint > J: # restricting it to be present and with the value > J: # parent. > > OK. > > J: # Similarly we want to say that the minCardinality > J: # is 1. > J: > J: InheritableClass rdfs:subClassOf _:min . > J: _:min rdf:type daml:Restriction . > J: _:min daml:onProperty daml:minCardinality . > J: _:min daml:hasValue "1" . > > As above. > > Now Inheritable class has both parts required for minimum cardinality > restrictions, but this is insufficient to make any difference, because they > are not in the RDF *graph*. > > J: # Now we want to restrict the class of the > J: # parent property, so we introduce > J: # toClass. > J: > J: InheritableClass rdfs:subClassOf _:to . > J: _:to rdf:type daml:Restriction . > J: _:to daml:onProperty daml:toClass . > J: _:to daml:cardinality "1" . > J: > J: # The above forces every InheritableClass > J: # to have a daml:toClass property. > > OK. > > This says that there is exactly one daml:toClass relationship. > > J: # Now we need to force that daml:toClass > J: # property to locally be a subPropertyOf > J: # identity. > J: > J: # Well, this too is possible (at least in > J: # the cardinality = 1 case) > J: > J: # Let's introduce a superProperty as a technical > J: # device. > J: > J: daml:toClass rdfs:subPropertyOf _:superProp . > J: daml:sameClassAs rdfs:subPropertyOf _:superProp . > > In the DAML+OIL model theory this does not have the meaning that one might > think with respect to restrictions. > > J: # We now restrict the cardinality of both > J: # the superProp and daml:sameClassAs to 1 > J: # on InheritableClass. > J: > J: InheritableClass rdfs:subClassOf _:sup . > J: _:sup rdf:type daml:Restriction . > J: _:sup daml:onProperty _:superProp . > J: _:sup daml:cardinality "1" . > J: > J: InheritableClass rdfs:subClassOf _:same . > J: _:same rdf:type daml:Restriction . > J: _:same daml:onProperty daml:sameClassAs . > J: _:same daml:cardinality "1" . > > So an instance of InheritableClass > - has a daml:onProperty relationship to parent > - has a daml:minCardinality relationship to "1" > - has a exactly one _:superProp relationship > and thus at most one daml:toClass relationship > and thus at most one daml:sameClassAs relationship > - has exactly one daml:sameClassAs relationship > So if it has a daml:toClass relationship to some object, then it also has a > daml:sameClassAs relationship to that same object. > > However, this does not provide any interesting consequences, as all these > relationships do not have to be in the RDF *graph* and that is all that can > trigger restriction consequences in the DAML+OIL model theory. > > peter > >
Received on Tuesday, 23 April 2002 08:12:44 UTC