Talk:RDF Schema

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Classes and subclasses?[edit]

Would it be correct to say the following should be added to the description of classes and subclasses:

foaf:Person rdf:Class rdf:Class


? If I got it right... --Dan|(talk) 15:23, 11 January 2010 (UTC)

This is a very old question, but just for closure, the triple that fits in this case is:

   foaf:Person rdf:type rdf:Class

However it is not necessary to add this to the description because it is entailed by

   ex:John rdf:type foaf:Person

because the rdfs:range of rdf:type is rdf:Class. — Preceding unsigned comment added by Greentaratoo (talkcontribs) 18:48, 3 March 2016 (UTC)

Mistake in rdf:XMLLiteral?[edit]

In the article, there is "rdf:XMLLiteral – the class of XML literal values. rdf:XMLLiteral is an instance of rdfs:Datatype (and thus a subclass of rdfs:Literal)." I think this should be replaced to "rdf:XMLLiteral – the class of XML literal values. rdf:XMLLiteral is an instance of rdfs:Datatype and a subclass of rdfs:Literal". Thre reason: looking at [1] rdf:XMLLiteral is an instance of rdfs:Datatype and a subclass of rdfs:Literal and according to [2] rdfs:Datatype is an instance of rdfs:Class and a subclass of rdfs:Class.

[1] http://www.w3.org/1999/02/22-rdf-syntax-ns [2] http://www.w3.org/2000/01/rdf-schema — Preceding unsigned comment added by Chrdebru (talkcontribs) 07:29, 12 January 2011 (UTC)

Error in Zoo/Cat/Animal Example[edit]

Just out of curiosity, isn't the definition of "Dog1" as a type of "Animal" incorrect? Dog1 is an example of an animal, but not a type. Art2welp (talk) 04:41, 12 February 2016 (UTC)

It's not defined as "a type of animal". The rdf:type of "Dog1" is "animal", but that's not the same thing (as you note, it just means that Dog1 is an example of an animal). On the other paw, "cat" is defined as "a type of animal" using rdfs:subClassOf. Andy Dingley (talk) 19:13, 12 February 2016 (UTC)

Yes ... and "cat1" is an rdf:type of "cat," which is a subClassOf "animal." I was really just trying to point out that rdf:type isn't very clearly defined, if that hierarchy isn't enforced. Perhaps we can add "cat1 rdf:type animal" to the example to at least illustrate that polyhierarchy. Art2welp (talk) 21:11, 17 February 2016 (UTC)

Concept of Well-Formed Graph Comes From Where?[edit]

There is no concept of "well-formed graph" defined in either the RDF or RDFS specification. Really there is nothing "ill-formed" about the graph in the example in the RDFS entailment section. If a property has a certain range (say ex:animal) and there is a triple that uses that predicate with a certain object (say ex:cat2), then under the RDFS entailment regime, one may infer that ex:cat2 rdf:type ex:animal. No "guessing" is needed or expected - this is just what RDFS entailment means. There is nothing in the graph to indicate that ex:cat is a subclass of ex:animal. Maybe that is what intended (e.g. "cat" stands for Caterpillar tractor) - that doesn't make the graph not "well-formed", whatever that means. There is no source given for this section, so I don't know where this material, or this "well-formed" concept - came from - certainly not from the RDFS specification itself. --Greentaratoo (talk) 01:55, 3 March 2016 (UTC

Take a look at the SPARQL standards and sections on "E-entailment". I'm not even going to try explaining it at this time of night. Andy Dingley (talk) 02:52, 3 March 2016 (UTC)
You are free to explain, if you like, at whatever time is convenient for you. As to the use of "well-formed" in the SPARQL spec., that is a reference to syntactic well-formedness, not about whether the graph actually entails what the author intended. For example, RDF doesn't allow literals in the subject position, so if the result of some mapping gives something that looks like an RDF triple except it has a literal in the subject position then it is not "well-formed", which is another way of saying it is not an RDF triple. This usage is consistent with the conventional terminology of "well-formed formulas". The graph in the example is well-formed RDF. There are no additional constraints on the graph for the RDFS entailment regime, so any RDF graph is well-formed w.r.t the RDFS entailment regime. "For example, under RDFS entailment, any SPARQL query is legal, but queries that require literals as a binding for a variable in a subject position have no answer because all mappings that result in a set of RDFS entailed triples are not well-formed RDF since RDF forbids literals in the subject position." If the section is to be entitled "RDFS entailment", then it should describe RDFS entailment as defined by the RDF 1.1 specification (https://www.w3.org/TR/rdf11-mt/), not "RDFS entailment regime", which is a different thing, as defined by the SPARQL spec. Otherwise change the name of the section, cite the SPARQL spec (which is a primary source for this concept) and define that concept. But it is not correct to claim that the RDFS entailment regime imposes any kind of restriction on either RDF graphs or SPARQL queries. --Greentaratoo (talk) 03:35, 3 March 2016 (UTC)

Secondary and Tertiary Sources for RDFS[edit]

--Greentaratoo (talk) 02:06, 3 March 2016 (UTC)

I wouldn't wipe my arse on anything from W3Schools. Andy Dingley (talk) 02:53, 3 March 2016 (UTC)

Fine, what do suggest as secondary and tertiary sources - SPARQL? That's the origin of the term "RDFS entailment regime", so its a primary source.--Greentaratoo (talk) 03:08, 3 March 2016 (UTC)

There's a vast pile of RDF secondary material out there in the last decade. Try academia for one, especially Manchester Uni. There really is no shortage. Andy Dingley (talk) 03:18, 3 March 2016 (UTC)
There is a shortage of such references in this article. --Greentaratoo (talk) 03:39, 3 March 2016 (UTC)

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