- From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
- Date: Tue, 13 Nov 2012 13:49:50 +0100
- To: Pat Hayes <phayes@ihmc.us>
- CC: Richard Cyganiak <richard@cyganiak.de>, Pierre-Antoine Champin <pierre-antoine.champin@liris.cnrs.fr>, RDF Working Group <public-rdf-wg@w3.org>
Le 13/11/2012 10:50, Pat Hayes a écrit : > > On Nov 13, 2012, at 1:31 AM, Antoine Zimmermann wrote: > >> Le 13/11/2012 09:31, Pat Hayes a écrit : >>> >>> On Nov 12, 2012, at 5:41 AM, Richard Cyganiak wrote: >>> >>>> ... But that's all besides the point. My question was why the >>>> specs distinguish between the two things in the first place. >>>> Even in XSD entailment, this is consistent: >>>> >>>> :a :b "xxx"^^xsd:integer. >>>> >>>> But this is not: >>>> >>>> :a :b "xxx"^^xsd:integer. :b rdfs:range rdfs:Literal. >>>> >>>> I don't understand the point of singling out the concept of >>>> the “ill-typed literal”, declaring it to be a “non-syntactic >>>> error”, but not declaring it to be an inconsistency. >>>> >>> >>> You completely miss the point. Nothing is being "singled out" in >>> the 2004 design. Inconsistency isn't something you get to >>> "declare", it's a word with a technical meaning. It means, the >>> graph is false in every interpretation. You get to define truth >>> conditions on triples, and then consistency is a product of >>> that. >>> >>> So, you want >>> >>>> :a :b "xxx"^^xsd:integer. >>> >>> to be always false in any XSD-interpretation, no matter what :a >>> and :b are interpreted to mean, right? That is what it means to >>> say that this triple is XSD-inconsistent. >>> >>> I don't think this is possible without tweaking the basic RDF >>> semantic rules. >>> >>> Here's the only way I can see of doing it. We require the >>> universe of every interpretation to contain a special semantic >>> value called "error", and we stipulate that no relational >>> extensions ever contain a pair <x, error>, and we also tweak the >>> blank node conditions so that bnodes are never mapped to error. >>> Then we say that any ill-formed literal is required to denote >>> error. This ensures that all triples with an ill-formed literal >>> will be false, so such graphs are always inconsistent. Note, this >>> has to be done in the basic RDF semantics, not just in the XSD >>> semantics, since adding datatypes to literals doesn't change what >>> URIs like :a and :b mean. >> >> I was thinking of something else: >> >> if <d> is an IRI in the datatype map, then for any character string >> aaa in the vocabulary V, < I(aaa^^<d>),I(<d>) > in >> IEXP(I(rdf:type)). >> >> For instance, if we have: >> >> <s> <p> "xyz"^^xsd:integer . >> >> By definition of D-interpretation, "xyz"^^xsd:integer has to be >> interpreted as a non literal. But with the constraint I just >> stated, the resource denoted by "xyz"^^xsd:integer must be of type >> xsd:integer, which, by virtue of XSD only contains integers, that >> are literals. Inconsistency! > > Yes, I thought of that, but I don't think it works. What you get is > an inconsistency in the metatheory, ie in the semantic conditions > themselves, not that the graph itself is false. I mean, if the > semantics says that something has to not be in LV and the semantics > also says that this same thing, whatever it is, has to be in LV, then > its the *semantics* which is inconsistent. What we want is that the > graph should be false in every interpretation, not that the semantics > should break :-) Not really but yes, it's weird. It means that there is no D-interpretation over a vocabulary that includes an ill-typed literals. This could work but I don't quite foresee the consequences. > I think allowing LV to be partial is the simplest and most intuitive > way to make this work. See my most recent email to Richard. Possibly yes. > > Pat > >> >>> >>> We didn't do this in 2004 because the basic RDF semantic >>> machinery was seen as being defined independently of literal >>> datatyping, but we could revisit this decision, I guess. I really >>> don't like this idea, but we could do it. It would amount to >>> incorporating datatype correctness checking into the basic RDF >>> semantic machinery, and we ought to check any consequences it >>> might have for OWL and RIF, as it is a rather basic change to the >>> design. >>> >>> Pat >> >> <skip> >> >> -- Antoine Zimmermann ISCOD / LSTI - Institut Henri Fayol École >> Nationale Supérieure des Mines de Saint-Étienne 158 cours Fauriel >> 42023 Saint-Étienne Cedex 2 France Tél:+33(0)4 77 42 66 03 >> Fax:+33(0)4 77 42 66 66 http://zimmer.aprilfoolsreview.com/ >> >> > > ------------------------------------------------------------ IHMC > (850)434 8903 or (650)494 3973 40 South Alcaniz St. > (850)202 4416 office Pensacola (850)202 > 4440 fax FL 32502 (850)291 0667 > mobile phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes > > > > > > -- Antoine Zimmermann ISCOD / LSTI - Institut Henri Fayol École Nationale Supérieure des Mines de Saint-Étienne 158 cours Fauriel 42023 Saint-Étienne Cedex 2 France Tél:+33(0)4 77 42 66 03 Fax:+33(0)4 77 42 66 66 http://zimmer.aprilfoolsreview.com/
Received on Tuesday, 13 November 2012 12:48:55 UTC