- From: Sandro Hawke <sandro@w3.org>
- Date: Wed, 18 Dec 2013 10:17:57 -0500
- To: Guus Schreiber <guus.schreiber@vu.nl>, 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 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...? -- 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 15:18:13 UTC