- From: Sandro Hawke <sandro@w3.org>
- Date: Sun, 20 Jan 2002 18:58:55 -0500
- To: "Arthur Barstow" <barstow@mediaone.net>
- cc: www-rdf-interest@w3.org
> The following defect report against the W3C's ARP-based RDF Validator: > > [1] http://lists.w3.org/Archives/Public/www-rdf-validator/2002Jan/0304.html > > suggests a violation of the following part of M&S: > > [[ > When a resource represents a reified statement; that is, it has an > RDF:type property with a value of RDF:Statement, then that resource > must have exactly one RDF:subject property, one RDF:object property, > and one RDF:predicate property. > ]] > > Since this defect report appears to be accurate and all of the online RDF > parsers (ARP, SWI, CARA, Profium, Raptor, RDFStore) listed at: > > [2] http://www.w3.org/People/Barstow/#online_parsers > > seem to have this defect, if you are responsible for a parser listed > at [2], you may want to review [1]. I think the text from M&S is simply expressing a cardinality constraint, part of the M&S (informal) ontology. Therefor this constraint should be handled when/if other ontology information is handled, and not in the RDF parser. The DAML/Description-Logics view on such constraints, by the way, is that the multiple values of unique properties are inferred to be equal, instead of saying the input is invalid. In other words, the input in [1] is perfectly valid (at first): it just implies that "http://schema/Contains" and "http://schema/WrittenBy" are symbols denoting the same thing. It also implies "Some Content" and "Some Author" are identical text strings, which leads to a contradiction which could/should cause the input to be flagged as invalid (not logically self-consistent). But that flagging is post-inference, not in the parser. -- sandro
Received on Sunday, 20 January 2002 18:59:29 UTC