- From: Birte Glimm <birte.glimm@comlab.ox.ac.uk>
- Date: Tue, 16 Feb 2010 10:22:31 +0000
- To: "Polleres, Axel" <axel.polleres@deri.org>
- Cc: lee@thefigtrees.net, ivan@w3.org, public-rdf-dawg@w3.org
OK :-) I'll add some explanation/examples/discussion of alternatives then. Birte On 16 February 2010 09:31, Polleres, Axel <axel.polleres@deri.org> wrote: > Birte, all, don't get me wrong... I just wanted those possible alternatives spelled out and to suggest that we add some explanations/examples that make this current behavior clear and explain why sparql does not behave like the alternatives mentioned, since I would expect that some people might find particularly variations of alternative 2 intuitive. So, I didn't mean to imply a change of direction. > > Best, > Axel > > ----- Original Message ----- > From: b.glimm@googlemail.com <b.glimm@googlemail.com> > To: Polleres, Axel > Cc: Lee Feigenbaum <lee@thefigtrees.net>; Ivan Herman <ivan@w3.org>; SPARQL Working Group <public-rdf-dawg@w3.org> > Sent: Mon Feb 15 20:45:23 2010 > Subject: Re: Entailment regimes open issues > > On 15 February 2010 16:29, Axel Polleres <axel.polleres@deri.org> wrote: >> >> Well, these (32 and 34) are definitly separate issues, but I guess we agree on that... > Yes and 32 just is not related to entailment regimes. > >> As for issue-34, I agree that we can close the issue if the single goal is that the >> behaviour is well defined... we have to be aware though, that results may not always >> and for everybody will be intuitive: in fact, although every current implementation >> probably treats bnodes just as constants under a kind of unique names assumption >> in aggregates like count (does anybody do anything different?) there would >> be alternative ways to handle bnodes in aggregates, like >> Alternative1: ignoring bnodes for aggregates (could be viewed reasonable conceptually, IMO) > > That is an alternative, but I like it less. For example the OWL WG > test results are recorded in an ontology that contains, for each test > a bnode (anonymous individual in OWL) which is related via several > properties to properties of the test in question, e.g., whether the > test is a consistency or an entailment test, whether the test failed > or passed etc. If you would ignore the bnodes/anonymous individuals, > you couldn't count the number of tests or the number of failing tests > etc. > I can list it as an alternative, but I wouldn't vote for including > this as the envisaged behavior. > >> Alternative2: for entaiment regimes like OWL which have an explicit notion of equality/inequality >> counting could be expected to just return the number of those >> - Alternative2a: known to be different >> - Alternative2b: not known to be the same > That means, however, that aggregation is no longer an algebra operator > as it is at the moment. E.g., if we query a graph/ontology containing: > ex:a a ex:C . > ex:b a ex:C . > (in FSS ClassAssertion(ex:C ex:a) and ClassAssertion(ex:C ex:b)) > with a query > SELECT ?x WHERE { ?x a ex:C } > then we get x/ex:a and x/ex:b under OWL entailment (Direct Semantics > and RDF-Based Semantics). Aggregates are then defined on top of that > and just sum up or count or whatever the normal matching algorithm > provides. I really wouldn't want to mess with that. > > Birte > >> Before just closing the issue, I would at least think that a sentence or two (and maybe examples) >> should be added that clarify that those behaviors are NOT provided by the current semantics. >> >> Axel >> >> >> On 11 Feb 2010, at 19:05, Birte Glimm wrote: >> >>> Just 32 means 34 I think: >>> [ISSUE 34]: How do entailment regimes interaction with aggregates, >>> grouping, and blank nodes? >>> Birte >>> >>> On 11 February 2010 14:16, Lee Feigenbaum <lee@thefigtrees.net> wrote: >>> > On 2/8/2010 2:02 AM, Ivan Herman wrote: >>> >> >>> >> I certainly agree with closing issues #28, #32, #40, #42. >>> >> >>> >> I would propose to leave #43 for a while to see how the SD work evolves. >>> >> I predict that what you write below is true, but maybe discussions on SD >>> >> will allow for a finer granularity... >>> > >>> > I will close issues 28, 32, 40, and 42 if there is no concerns raised within >>> > the next 7 days. >>> > >>> > Let's include issue 43 in our next TC discussion of service description. >>> > >>> > Lee >>> > >>> > >>> > >>> >>> >>> >>> -- >>> Dr. Birte Glimm, Room 306 >>> Computing Laboratory >>> Parks Road >>> Oxford >>> OX1 3QD >>> United Kingdom >>> +44 (0)1865 283529 >>> >>> >> >> >> > > > > -- > Dr. Birte Glimm, Room 306 > Computing Laboratory > Parks Road > Oxford > OX1 3QD > United Kingdom > +44 (0)1865 283529 > -- Dr. Birte Glimm, Room 306 Computing Laboratory Parks Road Oxford OX1 3QD United Kingdom +44 (0)1865 283529
Received on Tuesday, 16 February 2010 10:23:04 UTC