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Re: incompleteness in RDFS closure rules

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Tue, 10 Jun 2003 10:55:00 -0400 (EDT)
Message-Id: <20030610.105500.117138545.pfps@research.bell-labs.com>
To: phayes@ihmc.us
Cc: www-rdf-comments@w3.org, jos.deroo.jd@belgium.agfa.com, gk@ninebynine.org

From: pat hayes <phayes@ihmc.us>
Subject: Re: incompleteness in RDFS closure rules
Date: Mon, 9 Jun 2003 13:39:52 -0500

> >	rdfs:subClassOf rdfs:subPropertyOf xxx .
> >	xxx rdfs:domain yyy .
> >
> >RDFS-entails
> >
> >	rdfs:Class rdfs:subClassOf yyy .
> >
> >but this does not come out of the RDFS closure rules.
> >
> >
> >
> >	rdfs:subClassOf rdfs:subPropertyOf xxx .
> >	xxx rdfs:range yyy .
> >
> >RDFS-entails
> >
> >	rdfs:Class rdfs:subClassOf yyy .
> >
> >but this does not come out of the RDFS closure rules.
> >
> >
> >
> >	rdfs:subPropertyOf rdfs:subPropertyOf xxx .
> >	xxx rdfs:domain yyy .
> >
> >RDFS-entails
> >
> >	rdf:Property rdfs:subClassOf yyy .
> >
> >but this does not come out of the RDFS closure rules.
> >
> >
> >
> >	rdfs:subPropertyOf rdfs:subPropertyOf xxx .
> >	xxx rdfs:range yyy .
> >
> >RDFS-entails
> >
> >	rdf:Property rdfs:subClassOf yyy .
> >
> >but this does not come out of the RDFS closure rules.
> 
> 
> Yes, you are perfectly correct. The rule rdfs12 has been generalized 
> to include these cases, as follows:
> 
> rdfs12a
> 
> ppp rdfs:subPropertyOf zzz .
> ppp rdfs:domain xxx .
> zzz rdfs:domain yyy .
> |-
> xxx rdfs:subClassOf yyy .
> 
> rdfs12b
> 
> ppp rdfs:subPropertyOf zzz .
> ppp rdfs:range xxx .
> zzz rdfs:range yyy .
> |-
> xxx rdfs:subClassOf yyy .
> 
> where in 12a, ppp is one of rdf:type, rdfs:subPropertyOf, 
> rdfs:subClassOf, and in 12b only the last two are allowed (because an 
> empty class need not be in the range of a superproperty of rdf:type). 
> Including rdf:type in the 12a case covers the inference noticed 
> earlier by Herman, though the rationale is somewhat different.  These 
> rules are not valid more generally because of the inclusive nature of 
> domain and range.
> 
> BTW, the URI of the current editors draft has changed somewhat: these 
> changes are now visible at
> 
> http://www.ihmc.us/users/phayes/RDF_Semantics_Edit_nT.html
> 
> Thanks for noticing this.
> 
> Pat

I do not believe that these rules are valid.

For example, if I say

	rdfs:subPropertyOf rdfs:range rdfs:Resource .

which seems like a benign thing to say,  then I get the conclusion

	rdfs:Resource rdfs:subClassOf rdf:Property .

from rule rdfs12b.

peter
Received on Tuesday, 10 June 2003 10:55:22 GMT

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