- From: Guus Schreiber <guus.schreiber@vu.nl>
- Date: Wed, 18 Dec 2013 16:30:20 +0100
- To: Sandro Hawke <sandro@w3.org>, Ivan Herman <ivan@w3.org>, "Peter F. Patel-Schneider" <pfpschneider@gmail.com>
- CC: Olivier Corby <olivier.corby@inria.fr>, W3C RDF WG <public-rdf-wg@w3.org>
On 18-12-13 16:17, Sandro Hawke wrote: > On 12/18/2013 08:40 AM, Guus Schreiber wrote: >> >> >> On 18-12-13 13:12, Sandro Hawke wrote: >>> Ivan Herman <ivan@w3.org> wrote: >>>> Thanks Peter >>>> >>>> What effect does this have on the PR transition? Strictly speaking, we >>>> do not have two independent implementations for the complete test >>>> suite, ie, we have not fulfilled our exit criteria. Can there be a >>>> clear explanation that can be used to convince the Director that we can >>>> move ahead nevertheless? (I am looking for an elevator pitch equivalent >>>> of what you write below; something like "these tests are side-effect on >>>> the approach used for otherwise correct inference engines"...) One >>>> could actually argue whether these tests are correct in the first place >>>> if they are really dependent on the engines. >>>> >>> >>> One procedural technique would be to rescind those tests as not >>> helpful to interoperability. >> >> OK, so lets look at the two tests: >> >> 1. datatypes-intensional-xsd-integer-string-incompatible [1] >> >> xsd:integer rdfs:subClassOf xsd:string . >> false >> >> As I said earlier: this requires a form of disjointness reasoning >> (primitive datatypes are disjoint). Our ClioPatria reasoner handles it >> correctly, because we built a kind of first-principles reasoner. >> However, such an approach is typically not taken by tool builders, >> because it is not very efficient. The fact that the test is false will >> typically be built implicitly into the machinery, so the system can't >> actually say explictly it is wrong. >> >> I suggest that failing this test is therefore in practice not a threat >> to implementation interoperability. >> >> >> 2. xmlsch-02-whitespace-facet-3 [2] >> >> ex:a ex:prop "3"^^xsd:int . >> entails >> ex:a ex:prop [ a rdfs:Literal ] . >> >> A bit of the same story. Yes, it is true. When reasoning from first >> principles you would derive this fact. But why would an implementation >> care? >> >> What you do care about as implementer are the other datatype tests, e.g.: >> * when there is a mismatch/equality/.. between two literals >> * when there is a mismatch between a literal and its datatype. >> Those are interoperability issues. And we have plenty of tests for >> these. But these issues are not at stake in the two tests above. >> >> I therefore PROPOSE that these two tests be rescinded as they are not >> helpful to interoperability. >> > > That all makes sense. Are there other tests that should be rescinded > using this reasoning...? Possibly, but I don't have time to check. I know that many other datatype tests are really useful ones, from an interoperability point of view. Guus > > -- Sandro > >> Guus >> >> [1] >> https://dvcs.w3.org/hg/rdf/raw-file/default/rdf-mt/reports/index.html#test_datatypes-intensional-xsd-integer-string-incompatible >> >> [2] >> https://dvcs.w3.org/hg/rdf/raw-file/default/rdf-mt/reports/index.html#test_xmlsch-02-whitespace-facet-3 >> >>> >>> - Sandro >>> >>>> Thanks >>>> >>>> Ivan >>>> >>>> >>>> >>>> On 17 Dec 2013, at 21:55 , Peter F. Patel-Schneider >>>> <pfpschneider@gmail.com> wrote: >>>> >>>>> Here is my analysis of the two "failures" from Corese. >>>>> >>>>> datatypes-intensional-xsd-integer-string-incompatible >>>>> The test says that it is inconsistent to state that xsd:integer is >>>> a >>>>> subclass of xsd:string. >>>>> >>>>> As most implementations directly implement datatype reasoning, they >>>> don't >>>>> depend on this fact about integers and strings. They can correctly >>>> reason >>>>> about data values without noticing this invariant fact about the >>>> datatype >>>>> classes themselves. >>>>> >>>>> OWL implementations have to reason from facts like these, for example >>>> to >>>>> correctly infer that the intersection of string and integer is empty, >>>> and so >>>>> any property with both string and integer as a range can never have >>>> any >>>>> fillers. >>>>> >>>>> >>>>> xmlsch-02-whitespace-facet-3 >>>>> Test that an explicit literal implies a blank filler that is a >>>> Literal >>>>> >>>>> Most forward-chaining implementations of RDF reasoning do not >>>> directly >>>>> perform complete entailment. This kind of inference and perhaps one >>>> other >>>>> is then handled by a separate portion of the system, which appears to >>>> not be >>>>> part of the Corese that was used in the testing. >>>>> >>>>> >>>>> So, Corese appears to have a good implementation of the core of >>>> forward-chaining RDF entailment, but does not directly implement two >>>> special cases (one related to datatype intensions and one related to >>>> datatype extensions and blank nodes). >>>>> >>>>> >>>>> peter >>>>> >>>>> >>>>> >>>>> >>>>> On 12/17/2013 10:00 AM, Ivan Herman wrote: >>>>>> Looks much better! Thanks >>>>>> >>>>>> Guys, we have two implementations of semantics. One is 100% (hurray >>>> Jan!), one is almost 100%. Peter, it would probably be good to have a >>>> good idea tomorrow why Corese fails on two tests and whether those are >>>> essential in terms of testing. Put it another way, can we try to go to >>>> PR based on these test results? >>>>>> >>>>>> (We are still missing Michael Schreiber's report...) >>>>>> >>>>>> Ivan >>>>>> >>>>> >>>> >>>> >>>> ---- >>>> Ivan Herman, W3C >>>> Digital Publishing Activity Lead >>>> Home: http://www.w3.org/People/Ivan/ >>>> mobile: +31-641044153 >>>> GPG: 0x343F1A3D >>>> FOAF: http://www.ivan-herman.net/foaf >>> >>> >>> >> >
Received on Wednesday, 18 December 2013 15:30:49 UTC